power: reset: corrections for simple syscon reboot driver

[linux-2.6/btrfs-unstable.git] / drivers / iommu / intel-iommu.c

/*
 * Copyright © 2006-2014 Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * Authors: David Woodhouse <dwmw2@infradead.org>,
 *          Ashok Raj <ashok.raj@intel.com>,
 *          Shaohua Li <shaohua.li@intel.com>,
 *          Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
 *          Fenghua Yu <fenghua.yu@intel.com>
 */

#include <linux/init.h>
#include <linux/bitmap.h>
#include <linux/debugfs.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/pci.h>
#include <linux/dmar.h>
#include <linux/dma-mapping.h>
#include <linux/mempool.h>
#include <linux/memory.h>
#include <linux/timer.h>
#include <linux/iova.h>
#include <linux/iommu.h>
#include <linux/intel-iommu.h>
#include <linux/syscore_ops.h>
#include <linux/tboot.h>
#include <linux/dmi.h>
#include <linux/pci-ats.h>
#include <linux/memblock.h>
#include <linux/dma-contiguous.h>
#include <asm/irq_remapping.h>
#include <asm/cacheflush.h>
#include <asm/iommu.h>

#include "irq_remapping.h"

#define ROOT_SIZE               VTD_PAGE_SIZE
#define CONTEXT_SIZE            VTD_PAGE_SIZE

#define IS_GFX_DEVICE(pdev) ((pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY)
#define IS_ISA_DEVICE(pdev) ((pdev->class >> 8) == PCI_CLASS_BRIDGE_ISA)
#define IS_AZALIA(pdev) ((pdev)->vendor == 0x8086 && (pdev)->device == 0x3a3e)

#define IOAPIC_RANGE_START      (0xfee00000)
#define IOAPIC_RANGE_END        (0xfeefffff)
#define IOVA_START_ADDR         (0x1000)

#define DEFAULT_DOMAIN_ADDRESS_WIDTH 48

#define MAX_AGAW_WIDTH 64
#define MAX_AGAW_PFN_WIDTH      (MAX_AGAW_WIDTH - VTD_PAGE_SHIFT)

#define __DOMAIN_MAX_PFN(gaw)  ((((uint64_t)1) << (gaw-VTD_PAGE_SHIFT)) - 1)
#define __DOMAIN_MAX_ADDR(gaw) ((((uint64_t)1) << gaw) - 1)

/* We limit DOMAIN_MAX_PFN to fit in an unsigned long, and DOMAIN_MAX_ADDR
   to match. That way, we can use 'unsigned long' for PFNs with impunity. */
#define DOMAIN_MAX_PFN(gaw)     ((unsigned long) min_t(uint64_t, \
                                __DOMAIN_MAX_PFN(gaw), (unsigned long)-1))
#define DOMAIN_MAX_ADDR(gaw)    (((uint64_t)__DOMAIN_MAX_PFN(gaw)) << VTD_PAGE_SHIFT)

#define IOVA_PFN(addr)          ((addr) >> PAGE_SHIFT)
#define DMA_32BIT_PFN           IOVA_PFN(DMA_BIT_MASK(32))
#define DMA_64BIT_PFN           IOVA_PFN(DMA_BIT_MASK(64))

/* page table handling */
#define LEVEL_STRIDE            (9)
#define LEVEL_MASK              (((u64)1 << LEVEL_STRIDE) - 1)

/*
 * This bitmap is used to advertise the page sizes our hardware support
 * to the IOMMU core, which will then use this information to split
 * physically contiguous memory regions it is mapping into page sizes
 * that we support.
 *
 * Traditionally the IOMMU core just handed us the mappings directly,
 * after making sure the size is an order of a 4KiB page and that the
 * mapping has natural alignment.
 *
 * To retain this behavior, we currently advertise that we support
 * all page sizes that are an order of 4KiB.
 *
 * If at some point we'd like to utilize the IOMMU core's new behavior,
 * we could change this to advertise the real page sizes we support.
 */
#define INTEL_IOMMU_PGSIZES     (~0xFFFUL)

static inline int agaw_to_level(int agaw)
{
        return agaw + 2;
}

static inline int agaw_to_width(int agaw)
{
        return min_t(int, 30 + agaw * LEVEL_STRIDE, MAX_AGAW_WIDTH);
}

static inline int width_to_agaw(int width)
{
        return DIV_ROUND_UP(width - 30, LEVEL_STRIDE);
}

static inline unsigned int level_to_offset_bits(int level)
{
        return (level - 1) * LEVEL_STRIDE;
}

static inline int pfn_level_offset(unsigned long pfn, int level)
{
        return (pfn >> level_to_offset_bits(level)) & LEVEL_MASK;
}

static inline unsigned long level_mask(int level)
{
        return -1UL << level_to_offset_bits(level);
}

static inline unsigned long level_size(int level)
{
        return 1UL << level_to_offset_bits(level);
}

static inline unsigned long align_to_level(unsigned long pfn, int level)
{
        return (pfn + level_size(level) - 1) & level_mask(level);
}

static inline unsigned long lvl_to_nr_pages(unsigned int lvl)
{
        return  1 << min_t(int, (lvl - 1) * LEVEL_STRIDE, MAX_AGAW_PFN_WIDTH);
}

/* VT-d pages must always be _smaller_ than MM pages. Otherwise things
   are never going to work. */
static inline unsigned long dma_to_mm_pfn(unsigned long dma_pfn)
{
        return dma_pfn >> (PAGE_SHIFT - VTD_PAGE_SHIFT);
}

static inline unsigned long mm_to_dma_pfn(unsigned long mm_pfn)
{
        return mm_pfn << (PAGE_SHIFT - VTD_PAGE_SHIFT);
}
static inline unsigned long page_to_dma_pfn(struct page *pg)
{
        return mm_to_dma_pfn(page_to_pfn(pg));
}
static inline unsigned long virt_to_dma_pfn(void *p)
{
        return page_to_dma_pfn(virt_to_page(p));
}

/* global iommu list, set NULL for ignored DMAR units */
static struct intel_iommu **g_iommus;

static void __init check_tylersburg_isoch(void);
static int rwbf_quirk;

/*
 * set to 1 to panic kernel if can't successfully enable VT-d
 * (used when kernel is launched w/ TXT)
 */
static int force_on = 0;

/*
 * 0: Present
 * 1-11: Reserved
 * 12-63: Context Ptr (12 - (haw-1))
 * 64-127: Reserved
 */
struct root_entry {
        u64     val;
        u64     rsvd1;
};
#define ROOT_ENTRY_NR (VTD_PAGE_SIZE/sizeof(struct root_entry))
static inline bool root_present(struct root_entry *root)
{
        return (root->val & 1);
}
static inline void set_root_present(struct root_entry *root)
{
        root->val |= 1;
}
static inline void set_root_value(struct root_entry *root, unsigned long value)
{
        root->val |= value & VTD_PAGE_MASK;
}

static inline struct context_entry *
get_context_addr_from_root(struct root_entry *root)
{
        return (struct context_entry *)
                (root_present(root)?phys_to_virt(
                root->val & VTD_PAGE_MASK) :
                NULL);
}

/*
 * low 64 bits:
 * 0: present
 * 1: fault processing disable
 * 2-3: translation type
 * 12-63: address space root
 * high 64 bits:
 * 0-2: address width
 * 3-6: aval
 * 8-23: domain id
 */
struct context_entry {
        u64 lo;
        u64 hi;
};

static inline bool context_present(struct context_entry *context)
{
        return (context->lo & 1);
}
static inline void context_set_present(struct context_entry *context)
{
        context->lo |= 1;
}

static inline void context_set_fault_enable(struct context_entry *context)
{
        context->lo &= (((u64)-1) << 2) | 1;
}

static inline void context_set_translation_type(struct context_entry *context,
                                                unsigned long value)
{
        context->lo &= (((u64)-1) << 4) | 3;
        context->lo |= (value & 3) << 2;
}

static inline void context_set_address_root(struct context_entry *context,
                                            unsigned long value)
{
        context->lo |= value & VTD_PAGE_MASK;
}

static inline void context_set_address_width(struct context_entry *context,
                                             unsigned long value)
{
        context->hi |= value & 7;
}

static inline void context_set_domain_id(struct context_entry *context,
                                         unsigned long value)
{
        context->hi |= (value & ((1 << 16) - 1)) << 8;
}

static inline void context_clear_entry(struct context_entry *context)
{
        context->lo = 0;
        context->hi = 0;
}

/*
 * 0: readable
 * 1: writable
 * 2-6: reserved
 * 7: super page
 * 8-10: available
 * 11: snoop behavior
 * 12-63: Host physcial address
 */
struct dma_pte {
        u64 val;
};

static inline void dma_clear_pte(struct dma_pte *pte)
{
        pte->val = 0;
}

static inline u64 dma_pte_addr(struct dma_pte *pte)
{
#ifdef CONFIG_64BIT
        return pte->val & VTD_PAGE_MASK;
#else
        /* Must have a full atomic 64-bit read */
        return  __cmpxchg64(&pte->val, 0ULL, 0ULL) & VTD_PAGE_MASK;
#endif
}

static inline bool dma_pte_present(struct dma_pte *pte)
{
        return (pte->val & 3) != 0;
}

static inline bool dma_pte_superpage(struct dma_pte *pte)
{
        return (pte->val & DMA_PTE_LARGE_PAGE);
}

static inline int first_pte_in_page(struct dma_pte *pte)
{
        return !((unsigned long)pte & ~VTD_PAGE_MASK);
}

/*
 * This domain is a statically identity mapping domain.
 *      1. This domain creats a static 1:1 mapping to all usable memory.
 *      2. It maps to each iommu if successful.
 *      3. Each iommu mapps to this domain if successful.
 */
static struct dmar_domain *si_domain;
static int hw_pass_through = 1;

/* domain represents a virtual machine, more than one devices
 * across iommus may be owned in one domain, e.g. kvm guest.
 */
#define DOMAIN_FLAG_VIRTUAL_MACHINE     (1 << 0)

/* si_domain contains mulitple devices */
#define DOMAIN_FLAG_STATIC_IDENTITY     (1 << 1)

/* define the limit of IOMMUs supported in each domain */
#ifdef  CONFIG_X86
# define        IOMMU_UNITS_SUPPORTED   MAX_IO_APICS
#else
# define        IOMMU_UNITS_SUPPORTED   64
#endif

struct dmar_domain {
        int     id;                     /* domain id */
        int     nid;                    /* node id */
        DECLARE_BITMAP(iommu_bmp, IOMMU_UNITS_SUPPORTED);
                                        /* bitmap of iommus this domain uses*/

        struct list_head devices;       /* all devices' list */
        struct iova_domain iovad;       /* iova's that belong to this domain */

        struct dma_pte  *pgd;           /* virtual address */
        int             gaw;            /* max guest address width */

        /* adjusted guest address width, 0 is level 2 30-bit */
        int             agaw;

        int             flags;          /* flags to find out type of domain */

        int             iommu_coherency;/* indicate coherency of iommu access */
        int             iommu_snooping; /* indicate snooping control feature*/
        int             iommu_count;    /* reference count of iommu */
        int             iommu_superpage;/* Level of superpages supported:
                                           0 == 4KiB (no superpages), 1 == 2MiB,
                                           2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
        spinlock_t      iommu_lock;     /* protect iommu set in domain */
        u64             max_addr;       /* maximum mapped address */
};

/* PCI domain-device relationship */
struct device_domain_info {
        struct list_head link;  /* link to domain siblings */
        struct list_head global; /* link to global list */
        u8 bus;                 /* PCI bus number */
        u8 devfn;               /* PCI devfn number */
        struct device *dev; /* it's NULL for PCIe-to-PCI bridge */
        struct intel_iommu *iommu; /* IOMMU used by this device */
        struct dmar_domain *domain; /* pointer to domain */
};

struct dmar_rmrr_unit {
        struct list_head list;          /* list of rmrr units   */
        struct acpi_dmar_header *hdr;   /* ACPI header          */
        u64     base_address;           /* reserved base address*/
        u64     end_address;            /* reserved end address */
        struct dmar_dev_scope *devices; /* target devices */
        int     devices_cnt;            /* target device count */
};

struct dmar_atsr_unit {
        struct list_head list;          /* list of ATSR units */
        struct acpi_dmar_header *hdr;   /* ACPI header */
        struct dmar_dev_scope *devices; /* target devices */
        int devices_cnt;                /* target device count */
        u8 include_all:1;               /* include all ports */
};

static LIST_HEAD(dmar_atsr_units);
static LIST_HEAD(dmar_rmrr_units);

#define for_each_rmrr_units(rmrr) \
        list_for_each_entry(rmrr, &dmar_rmrr_units, list)

static void flush_unmaps_timeout(unsigned long data);

static DEFINE_TIMER(unmap_timer,  flush_unmaps_timeout, 0, 0);

#define HIGH_WATER_MARK 250
struct deferred_flush_tables {
        int next;
        struct iova *iova[HIGH_WATER_MARK];
        struct dmar_domain *domain[HIGH_WATER_MARK];
        struct page *freelist[HIGH_WATER_MARK];
};

static struct deferred_flush_tables *deferred_flush;

/* bitmap for indexing intel_iommus */
static int g_num_of_iommus;

static DEFINE_SPINLOCK(async_umap_flush_lock);
static LIST_HEAD(unmaps_to_do);

static int timer_on;
static long list_size;

static void domain_exit(struct dmar_domain *domain);
static void domain_remove_dev_info(struct dmar_domain *domain);
static void domain_remove_one_dev_info(struct dmar_domain *domain,
                                       struct device *dev);
static void iommu_detach_dependent_devices(struct intel_iommu *iommu,
                                           struct device *dev);
static int domain_detach_iommu(struct dmar_domain *domain,
                               struct intel_iommu *iommu);

#ifdef CONFIG_INTEL_IOMMU_DEFAULT_ON
int dmar_disabled = 0;
#else
int dmar_disabled = 1;
#endif /*CONFIG_INTEL_IOMMU_DEFAULT_ON*/

int intel_iommu_enabled = 0;
EXPORT_SYMBOL_GPL(intel_iommu_enabled);

static int dmar_map_gfx = 1;
static int dmar_forcedac;
static int intel_iommu_strict;
static int intel_iommu_superpage = 1;

int intel_iommu_gfx_mapped;
EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);

#define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
static DEFINE_SPINLOCK(device_domain_lock);
static LIST_HEAD(device_domain_list);

static const struct iommu_ops intel_iommu_ops;

static int __init intel_iommu_setup(char *str)
{
        if (!str)
                return -EINVAL;
        while (*str) {
                if (!strncmp(str, "on", 2)) {
                        dmar_disabled = 0;
                        printk(KERN_INFO "Intel-IOMMU: enabled\n");
                } else if (!strncmp(str, "off", 3)) {
                        dmar_disabled = 1;
                        printk(KERN_INFO "Intel-IOMMU: disabled\n");
                } else if (!strncmp(str, "igfx_off", 8)) {
                        dmar_map_gfx = 0;
                        printk(KERN_INFO
                                "Intel-IOMMU: disable GFX device mapping\n");
                } else if (!strncmp(str, "forcedac", 8)) {
                        printk(KERN_INFO
                                "Intel-IOMMU: Forcing DAC for PCI devices\n");
                        dmar_forcedac = 1;
                } else if (!strncmp(str, "strict", 6)) {
                        printk(KERN_INFO
                                "Intel-IOMMU: disable batched IOTLB flush\n");
                        intel_iommu_strict = 1;
                } else if (!strncmp(str, "sp_off", 6)) {
                        printk(KERN_INFO
                                "Intel-IOMMU: disable supported super page\n");
                        intel_iommu_superpage = 0;
                }

                str += strcspn(str, ",");
                while (*str == ',')
                        str++;
        }
        return 0;
}
__setup("intel_iommu=", intel_iommu_setup);

static struct kmem_cache *iommu_domain_cache;
static struct kmem_cache *iommu_devinfo_cache;
static struct kmem_cache *iommu_iova_cache;

static inline void *alloc_pgtable_page(int node)
{
        struct page *page;
        void *vaddr = NULL;

        page = alloc_pages_node(node, GFP_ATOMIC | __GFP_ZERO, 0);
        if (page)
                vaddr = page_address(page);
        return vaddr;
}

static inline void free_pgtable_page(void *vaddr)
{
        free_page((unsigned long)vaddr);
}

static inline void *alloc_domain_mem(void)
{
        return kmem_cache_alloc(iommu_domain_cache, GFP_ATOMIC);
}

static void free_domain_mem(void *vaddr)
{
        kmem_cache_free(iommu_domain_cache, vaddr);
}

static inline void * alloc_devinfo_mem(void)
{
        return kmem_cache_alloc(iommu_devinfo_cache, GFP_ATOMIC);
}

static inline void free_devinfo_mem(void *vaddr)
{
        kmem_cache_free(iommu_devinfo_cache, vaddr);
}

struct iova *alloc_iova_mem(void)
{
        return kmem_cache_alloc(iommu_iova_cache, GFP_ATOMIC);
}

void free_iova_mem(struct iova *iova)
{
        kmem_cache_free(iommu_iova_cache, iova);
}

static inline int domain_type_is_vm(struct dmar_domain *domain)
{
        return domain->flags & DOMAIN_FLAG_VIRTUAL_MACHINE;
}

static inline int domain_type_is_vm_or_si(struct dmar_domain *domain)
{
        return domain->flags & (DOMAIN_FLAG_VIRTUAL_MACHINE |
                                DOMAIN_FLAG_STATIC_IDENTITY);
}

static inline int domain_pfn_supported(struct dmar_domain *domain,
                                       unsigned long pfn)
{
        int addr_width = agaw_to_width(domain->agaw) - VTD_PAGE_SHIFT;

        return !(addr_width < BITS_PER_LONG && pfn >> addr_width);
}

static int __iommu_calculate_agaw(struct intel_iommu *iommu, int max_gaw)
{
        unsigned long sagaw;
        int agaw = -1;

        sagaw = cap_sagaw(iommu->cap);
        for (agaw = width_to_agaw(max_gaw);
             agaw >= 0; agaw--) {
                if (test_bit(agaw, &sagaw))
                        break;
        }

        return agaw;
}

/*
 * Calculate max SAGAW for each iommu.
 */
int iommu_calculate_max_sagaw(struct intel_iommu *iommu)
{
        return __iommu_calculate_agaw(iommu, MAX_AGAW_WIDTH);
}

/*
 * calculate agaw for each iommu.
 * "SAGAW" may be different across iommus, use a default agaw, and
 * get a supported less agaw for iommus that don't support the default agaw.
 */
int iommu_calculate_agaw(struct intel_iommu *iommu)
{
        return __iommu_calculate_agaw(iommu, DEFAULT_DOMAIN_ADDRESS_WIDTH);
}

/* This functionin only returns single iommu in a domain */
static struct intel_iommu *domain_get_iommu(struct dmar_domain *domain)
{
        int iommu_id;

        /* si_domain and vm domain should not get here. */
        BUG_ON(domain_type_is_vm_or_si(domain));
        iommu_id = find_first_bit(domain->iommu_bmp, g_num_of_iommus);
        if (iommu_id < 0 || iommu_id >= g_num_of_iommus)
                return NULL;

        return g_iommus[iommu_id];
}

static void domain_update_iommu_coherency(struct dmar_domain *domain)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int i, found = 0;

        domain->iommu_coherency = 1;

        for_each_set_bit(i, domain->iommu_bmp, g_num_of_iommus) {
                found = 1;
                if (!ecap_coherent(g_iommus[i]->ecap)) {
                        domain->iommu_coherency = 0;
                        break;
                }
        }
        if (found)
                return;

        /* No hardware attached; use lowest common denominator */
        rcu_read_lock();
        for_each_active_iommu(iommu, drhd) {
                if (!ecap_coherent(iommu->ecap)) {
                        domain->iommu_coherency = 0;
                        break;
                }
        }
        rcu_read_unlock();
}

static int domain_update_iommu_snooping(struct intel_iommu *skip)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int ret = 1;

        rcu_read_lock();
        for_each_active_iommu(iommu, drhd) {
                if (iommu != skip) {
                        if (!ecap_sc_support(iommu->ecap)) {
                                ret = 0;
                                break;
                        }
                }
        }
        rcu_read_unlock();

        return ret;
}

static int domain_update_iommu_superpage(struct intel_iommu *skip)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int mask = 0xf;

        if (!intel_iommu_superpage) {
                return 0;
        }

        /* set iommu_superpage to the smallest common denominator */
        rcu_read_lock();
        for_each_active_iommu(iommu, drhd) {
                if (iommu != skip) {
                        mask &= cap_super_page_val(iommu->cap);
                        if (!mask)
                                break;
                }
        }
        rcu_read_unlock();

        return fls(mask);
}

/* Some capabilities may be different across iommus */
static void domain_update_iommu_cap(struct dmar_domain *domain)
{
        domain_update_iommu_coherency(domain);
        domain->iommu_snooping = domain_update_iommu_snooping(NULL);
        domain->iommu_superpage = domain_update_iommu_superpage(NULL);
}

static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
{
        struct dmar_drhd_unit *drhd = NULL;
        struct intel_iommu *iommu;
        struct device *tmp;
        struct pci_dev *ptmp, *pdev = NULL;
        u16 segment = 0;
        int i;

        if (dev_is_pci(dev)) {
                pdev = to_pci_dev(dev);
                segment = pci_domain_nr(pdev->bus);
        } else if (ACPI_COMPANION(dev))
                dev = &ACPI_COMPANION(dev)->dev;

        rcu_read_lock();
        for_each_active_iommu(iommu, drhd) {
                if (pdev && segment != drhd->segment)
                        continue;

                for_each_active_dev_scope(drhd->devices,
                                          drhd->devices_cnt, i, tmp) {
                        if (tmp == dev) {
                                *bus = drhd->devices[i].bus;
                                *devfn = drhd->devices[i].devfn;
                                goto out;
                        }

                        if (!pdev || !dev_is_pci(tmp))
                                continue;

                        ptmp = to_pci_dev(tmp);
                        if (ptmp->subordinate &&
                            ptmp->subordinate->number <= pdev->bus->number &&
                            ptmp->subordinate->busn_res.end >= pdev->bus->number)
                                goto got_pdev;
                }

                if (pdev && drhd->include_all) {
                got_pdev:
                        *bus = pdev->bus->number;
                        *devfn = pdev->devfn;
                        goto out;
                }
        }
        iommu = NULL;
 out:
        rcu_read_unlock();

        return iommu;
}

static void domain_flush_cache(struct dmar_domain *domain,
                               void *addr, int size)
{
        if (!domain->iommu_coherency)
                clflush_cache_range(addr, size);
}

/* Gets context entry for a given bus and devfn */
static struct context_entry * device_to_context_entry(struct intel_iommu *iommu,
                u8 bus, u8 devfn)
{
        struct root_entry *root;
        struct context_entry *context;
        unsigned long phy_addr;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);
        root = &iommu->root_entry[bus];
        context = get_context_addr_from_root(root);
        if (!context) {
                context = (struct context_entry *)
                                alloc_pgtable_page(iommu->node);
                if (!context) {
                        spin_unlock_irqrestore(&iommu->lock, flags);
                        return NULL;
                }
                __iommu_flush_cache(iommu, (void *)context, CONTEXT_SIZE);
                phy_addr = virt_to_phys((void *)context);
                set_root_value(root, phy_addr);
                set_root_present(root);
                __iommu_flush_cache(iommu, root, sizeof(*root));
        }
        spin_unlock_irqrestore(&iommu->lock, flags);
        return &context[devfn];
}

static int device_context_mapped(struct intel_iommu *iommu, u8 bus, u8 devfn)
{
        struct root_entry *root;
        struct context_entry *context;
        int ret;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);
        root = &iommu->root_entry[bus];
        context = get_context_addr_from_root(root);
        if (!context) {
                ret = 0;
                goto out;
        }
        ret = context_present(&context[devfn]);
out:
        spin_unlock_irqrestore(&iommu->lock, flags);
        return ret;
}

static void clear_context_table(struct intel_iommu *iommu, u8 bus, u8 devfn)
{
        struct root_entry *root;
        struct context_entry *context;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);
        root = &iommu->root_entry[bus];
        context = get_context_addr_from_root(root);
        if (context) {
                context_clear_entry(&context[devfn]);
                __iommu_flush_cache(iommu, &context[devfn], \
                        sizeof(*context));
        }
        spin_unlock_irqrestore(&iommu->lock, flags);
}

static void free_context_table(struct intel_iommu *iommu)
{
        struct root_entry *root;
        int i;
        unsigned long flags;
        struct context_entry *context;

        spin_lock_irqsave(&iommu->lock, flags);
        if (!iommu->root_entry) {
                goto out;
        }
        for (i = 0; i < ROOT_ENTRY_NR; i++) {
                root = &iommu->root_entry[i];
                context = get_context_addr_from_root(root);
                if (context)
                        free_pgtable_page(context);
        }
        free_pgtable_page(iommu->root_entry);
        iommu->root_entry = NULL;
out:
        spin_unlock_irqrestore(&iommu->lock, flags);
}

static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain,
                                      unsigned long pfn, int *target_level)
{
        struct dma_pte *parent, *pte = NULL;
        int level = agaw_to_level(domain->agaw);
        int offset;

        BUG_ON(!domain->pgd);

        if (!domain_pfn_supported(domain, pfn))
                /* Address beyond IOMMU's addressing capabilities. */
                return NULL;

        parent = domain->pgd;

        while (1) {
                void *tmp_page;

                offset = pfn_level_offset(pfn, level);
                pte = &parent[offset];
                if (!*target_level && (dma_pte_superpage(pte) || !dma_pte_present(pte)))
                        break;
                if (level == *target_level)
                        break;

                if (!dma_pte_present(pte)) {
                        uint64_t pteval;

                        tmp_page = alloc_pgtable_page(domain->nid);

                        if (!tmp_page)
                                return NULL;

                        domain_flush_cache(domain, tmp_page, VTD_PAGE_SIZE);
                        pteval = ((uint64_t)virt_to_dma_pfn(tmp_page) << VTD_PAGE_SHIFT) | DMA_PTE_READ | DMA_PTE_WRITE;
                        if (cmpxchg64(&pte->val, 0ULL, pteval))
                                /* Someone else set it while we were thinking; use theirs. */
                                free_pgtable_page(tmp_page);
                        else
                                domain_flush_cache(domain, pte, sizeof(*pte));
                }
                if (level == 1)
                        break;

                parent = phys_to_virt(dma_pte_addr(pte));
                level--;
        }

        if (!*target_level)
                *target_level = level;

        return pte;
}


/* return address's pte at specific level */
static struct dma_pte *dma_pfn_level_pte(struct dmar_domain *domain,
                                         unsigned long pfn,
                                         int level, int *large_page)
{
        struct dma_pte *parent, *pte = NULL;
        int total = agaw_to_level(domain->agaw);
        int offset;

        parent = domain->pgd;
        while (level <= total) {
                offset = pfn_level_offset(pfn, total);
                pte = &parent[offset];
                if (level == total)
                        return pte;

                if (!dma_pte_present(pte)) {
                        *large_page = total;
                        break;
                }

                if (dma_pte_superpage(pte)) {
                        *large_page = total;
                        return pte;
                }

                parent = phys_to_virt(dma_pte_addr(pte));
                total--;
        }
        return NULL;
}

/* clear last level pte, a tlb flush should be followed */
static void dma_pte_clear_range(struct dmar_domain *domain,
                                unsigned long start_pfn,
                                unsigned long last_pfn)
{
        unsigned int large_page = 1;
        struct dma_pte *first_pte, *pte;

        BUG_ON(!domain_pfn_supported(domain, start_pfn));
        BUG_ON(!domain_pfn_supported(domain, last_pfn));
        BUG_ON(start_pfn > last_pfn);

        /* we don't need lock here; nobody else touches the iova range */
        do {
                large_page = 1;
                first_pte = pte = dma_pfn_level_pte(domain, start_pfn, 1, &large_page);
                if (!pte) {
                        start_pfn = align_to_level(start_pfn + 1, large_page + 1);
                        continue;
                }
                do {
                        dma_clear_pte(pte);
                        start_pfn += lvl_to_nr_pages(large_page);
                        pte++;
                } while (start_pfn <= last_pfn && !first_pte_in_page(pte));

                domain_flush_cache(domain, first_pte,
                                   (void *)pte - (void *)first_pte);

        } while (start_pfn && start_pfn <= last_pfn);
}

static void dma_pte_free_level(struct dmar_domain *domain, int level,
                               struct dma_pte *pte, unsigned long pfn,
                               unsigned long start_pfn, unsigned long last_pfn)
{
        pfn = max(start_pfn, pfn);
        pte = &pte[pfn_level_offset(pfn, level)];

        do {
                unsigned long level_pfn;
                struct dma_pte *level_pte;

                if (!dma_pte_present(pte) || dma_pte_superpage(pte))
                        goto next;

                level_pfn = pfn & level_mask(level - 1);
                level_pte = phys_to_virt(dma_pte_addr(pte));

                if (level > 2)
                        dma_pte_free_level(domain, level - 1, level_pte,
                                           level_pfn, start_pfn, last_pfn);

                /* If range covers entire pagetable, free it */
                if (!(start_pfn > level_pfn ||
                      last_pfn < level_pfn + level_size(level) - 1)) {
                        dma_clear_pte(pte);
                        domain_flush_cache(domain, pte, sizeof(*pte));
                        free_pgtable_page(level_pte);
                }
next:
                pfn += level_size(level);
        } while (!first_pte_in_page(++pte) && pfn <= last_pfn);
}

/* free page table pages. last level pte should already be cleared */
static void dma_pte_free_pagetable(struct dmar_domain *domain,
                                   unsigned long start_pfn,
                                   unsigned long last_pfn)
{
        BUG_ON(!domain_pfn_supported(domain, start_pfn));
        BUG_ON(!domain_pfn_supported(domain, last_pfn));
        BUG_ON(start_pfn > last_pfn);

        dma_pte_clear_range(domain, start_pfn, last_pfn);

        /* We don't need lock here; nobody else touches the iova range */
        dma_pte_free_level(domain, agaw_to_level(domain->agaw),
                           domain->pgd, 0, start_pfn, last_pfn);

        /* free pgd */
        if (start_pfn == 0 && last_pfn == DOMAIN_MAX_PFN(domain->gaw)) {
                free_pgtable_page(domain->pgd);
                domain->pgd = NULL;
        }
}

/* When a page at a given level is being unlinked from its parent, we don't
   need to *modify* it at all. All we need to do is make a list of all the
   pages which can be freed just as soon as we've flushed the IOTLB and we
   know the hardware page-walk will no longer touch them.
   The 'pte' argument is the *parent* PTE, pointing to the page that is to
   be freed. */
static struct page *dma_pte_list_pagetables(struct dmar_domain *domain,
                                            int level, struct dma_pte *pte,
                                            struct page *freelist)
{
        struct page *pg;

        pg = pfn_to_page(dma_pte_addr(pte) >> PAGE_SHIFT);
        pg->freelist = freelist;
        freelist = pg;

        if (level == 1)
                return freelist;

        pte = page_address(pg);
        do {
                if (dma_pte_present(pte) && !dma_pte_superpage(pte))
                        freelist = dma_pte_list_pagetables(domain, level - 1,
                                                           pte, freelist);
                pte++;
        } while (!first_pte_in_page(pte));

        return freelist;
}

static struct page *dma_pte_clear_level(struct dmar_domain *domain, int level,
                                        struct dma_pte *pte, unsigned long pfn,
                                        unsigned long start_pfn,
                                        unsigned long last_pfn,
                                        struct page *freelist)
{
        struct dma_pte *first_pte = NULL, *last_pte = NULL;

        pfn = max(start_pfn, pfn);
        pte = &pte[pfn_level_offset(pfn, level)];

        do {
                unsigned long level_pfn;

                if (!dma_pte_present(pte))
                        goto next;

                level_pfn = pfn & level_mask(level);

                /* If range covers entire pagetable, free it */
                if (start_pfn <= level_pfn &&
                    last_pfn >= level_pfn + level_size(level) - 1) {
                        /* These suborbinate page tables are going away entirely. Don't
                           bother to clear them; we're just going to *free* them. */
                        if (level > 1 && !dma_pte_superpage(pte))
                                freelist = dma_pte_list_pagetables(domain, level - 1, pte, freelist);

                        dma_clear_pte(pte);
                        if (!first_pte)
                                first_pte = pte;
                        last_pte = pte;
                } else if (level > 1) {
                        /* Recurse down into a level that isn't *entirely* obsolete */
                        freelist = dma_pte_clear_level(domain, level - 1,
                                                       phys_to_virt(dma_pte_addr(pte)),
                                                       level_pfn, start_pfn, last_pfn,
                                                       freelist);
                }
next:
                pfn += level_size(level);
        } while (!first_pte_in_page(++pte) && pfn <= last_pfn);

        if (first_pte)
                domain_flush_cache(domain, first_pte,
                                   (void *)++last_pte - (void *)first_pte);

        return freelist;
}

/* We can't just free the pages because the IOMMU may still be walking
   the page tables, and may have cached the intermediate levels. The
   pages can only be freed after the IOTLB flush has been done. */
struct page *domain_unmap(struct dmar_domain *domain,
                          unsigned long start_pfn,
                          unsigned long last_pfn)
{
        struct page *freelist = NULL;

        BUG_ON(!domain_pfn_supported(domain, start_pfn));
        BUG_ON(!domain_pfn_supported(domain, last_pfn));
        BUG_ON(start_pfn > last_pfn);

        /* we don't need lock here; nobody else touches the iova range */
        freelist = dma_pte_clear_level(domain, agaw_to_level(domain->agaw),
                                       domain->pgd, 0, start_pfn, last_pfn, NULL);

        /* free pgd */
        if (start_pfn == 0 && last_pfn == DOMAIN_MAX_PFN(domain->gaw)) {
                struct page *pgd_page = virt_to_page(domain->pgd);
                pgd_page->freelist = freelist;
                freelist = pgd_page;

                domain->pgd = NULL;
        }

        return freelist;
}

void dma_free_pagelist(struct page *freelist)
{
        struct page *pg;

        while ((pg = freelist)) {
                freelist = pg->freelist;
                free_pgtable_page(page_address(pg));
        }
}

/* iommu handling */
static int iommu_alloc_root_entry(struct intel_iommu *iommu)
{
        struct root_entry *root;
        unsigned long flags;

        root = (struct root_entry *)alloc_pgtable_page(iommu->node);
        if (!root)
                return -ENOMEM;

        __iommu_flush_cache(iommu, root, ROOT_SIZE);

        spin_lock_irqsave(&iommu->lock, flags);
        iommu->root_entry = root;
        spin_unlock_irqrestore(&iommu->lock, flags);

        return 0;
}

static void iommu_set_root_entry(struct intel_iommu *iommu)
{
        void *addr;
        u32 sts;
        unsigned long flag;

        addr = iommu->root_entry;

        raw_spin_lock_irqsave(&iommu->register_lock, flag);
        dmar_writeq(iommu->reg + DMAR_RTADDR_REG, virt_to_phys(addr));

        writel(iommu->gcmd | DMA_GCMD_SRTP, iommu->reg + DMAR_GCMD_REG);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (sts & DMA_GSTS_RTPS), sts);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
}

static void iommu_flush_write_buffer(struct intel_iommu *iommu)
{
        u32 val;
        unsigned long flag;

        if (!rwbf_quirk && !cap_rwbf(iommu->cap))
                return;

        raw_spin_lock_irqsave(&iommu->register_lock, flag);
        writel(iommu->gcmd | DMA_GCMD_WBF, iommu->reg + DMAR_GCMD_REG);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (!(val & DMA_GSTS_WBFS)), val);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
}

/* return value determine if we need a write buffer flush */
static void __iommu_flush_context(struct intel_iommu *iommu,
                                  u16 did, u16 source_id, u8 function_mask,
                                  u64 type)
{
        u64 val = 0;
        unsigned long flag;

        switch (type) {
        case DMA_CCMD_GLOBAL_INVL:
                val = DMA_CCMD_GLOBAL_INVL;
                break;
        case DMA_CCMD_DOMAIN_INVL:
                val = DMA_CCMD_DOMAIN_INVL|DMA_CCMD_DID(did);
                break;
        case DMA_CCMD_DEVICE_INVL:
                val = DMA_CCMD_DEVICE_INVL|DMA_CCMD_DID(did)
                        | DMA_CCMD_SID(source_id) | DMA_CCMD_FM(function_mask);
                break;
        default:
                BUG();
        }
        val |= DMA_CCMD_ICC;

        raw_spin_lock_irqsave(&iommu->register_lock, flag);
        dmar_writeq(iommu->reg + DMAR_CCMD_REG, val);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, DMAR_CCMD_REG,
                dmar_readq, (!(val & DMA_CCMD_ICC)), val);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
}

/* return value determine if we need a write buffer flush */
static void __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did,
                                u64 addr, unsigned int size_order, u64 type)
{
        int tlb_offset = ecap_iotlb_offset(iommu->ecap);
        u64 val = 0, val_iva = 0;
        unsigned long flag;

        switch (type) {
        case DMA_TLB_GLOBAL_FLUSH:
                /* global flush doesn't need set IVA_REG */
                val = DMA_TLB_GLOBAL_FLUSH|DMA_TLB_IVT;
                break;
        case DMA_TLB_DSI_FLUSH:
                val = DMA_TLB_DSI_FLUSH|DMA_TLB_IVT|DMA_TLB_DID(did);
                break;
        case DMA_TLB_PSI_FLUSH:
                val = DMA_TLB_PSI_FLUSH|DMA_TLB_IVT|DMA_TLB_DID(did);
                /* IH bit is passed in as part of address */
                val_iva = size_order | addr;
                break;
        default:
                BUG();
        }
        /* Note: set drain read/write */
#if 0
        /*
         * This is probably to be super secure.. Looks like we can
         * ignore it without any impact.
         */
        if (cap_read_drain(iommu->cap))
                val |= DMA_TLB_READ_DRAIN;
#endif
        if (cap_write_drain(iommu->cap))
                val |= DMA_TLB_WRITE_DRAIN;

        raw_spin_lock_irqsave(&iommu->register_lock, flag);
        /* Note: Only uses first TLB reg currently */
        if (val_iva)
                dmar_writeq(iommu->reg + tlb_offset, val_iva);
        dmar_writeq(iommu->reg + tlb_offset + 8, val);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, tlb_offset + 8,
                dmar_readq, (!(val & DMA_TLB_IVT)), val);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flag);

        /* check IOTLB invalidation granularity */
        if (DMA_TLB_IAIG(val) == 0)
                printk(KERN_ERR"IOMMU: flush IOTLB failed\n");
        if (DMA_TLB_IAIG(val) != DMA_TLB_IIRG(type))
                pr_debug("IOMMU: tlb flush request %Lx, actual %Lx\n",
                        (unsigned long long)DMA_TLB_IIRG(type),
                        (unsigned long long)DMA_TLB_IAIG(val));
}

static struct device_domain_info *
iommu_support_dev_iotlb (struct dmar_domain *domain, struct intel_iommu *iommu,
                         u8 bus, u8 devfn)
{
        int found = 0;
        unsigned long flags;
        struct device_domain_info *info;
        struct pci_dev *pdev;

        if (!ecap_dev_iotlb_support(iommu->ecap))
                return NULL;

        if (!iommu->qi)
                return NULL;

        spin_lock_irqsave(&device_domain_lock, flags);
        list_for_each_entry(info, &domain->devices, link)
                if (info->iommu == iommu && info->bus == bus &&
                    info->devfn == devfn) {
                        found = 1;
                        break;
                }
        spin_unlock_irqrestore(&device_domain_lock, flags);

        if (!found || !info->dev || !dev_is_pci(info->dev))
                return NULL;

        pdev = to_pci_dev(info->dev);

        if (!pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_ATS))
                return NULL;

        if (!dmar_find_matched_atsr_unit(pdev))
                return NULL;

        return info;
}

static void iommu_enable_dev_iotlb(struct device_domain_info *info)
{
        if (!info || !dev_is_pci(info->dev))
                return;

        pci_enable_ats(to_pci_dev(info->dev), VTD_PAGE_SHIFT);
}

static void iommu_disable_dev_iotlb(struct device_domain_info *info)
{
        if (!info->dev || !dev_is_pci(info->dev) ||
            !pci_ats_enabled(to_pci_dev(info->dev)))
                return;

        pci_disable_ats(to_pci_dev(info->dev));
}

static void iommu_flush_dev_iotlb(struct dmar_domain *domain,
                                  u64 addr, unsigned mask)
{
        u16 sid, qdep;
        unsigned long flags;
        struct device_domain_info *info;

        spin_lock_irqsave(&device_domain_lock, flags);
        list_for_each_entry(info, &domain->devices, link) {
                struct pci_dev *pdev;
                if (!info->dev || !dev_is_pci(info->dev))
                        continue;

                pdev = to_pci_dev(info->dev);
                if (!pci_ats_enabled(pdev))
                        continue;

                sid = info->bus << 8 | info->devfn;
                qdep = pci_ats_queue_depth(pdev);
                qi_flush_dev_iotlb(info->iommu, sid, qdep, addr, mask);
        }
        spin_unlock_irqrestore(&device_domain_lock, flags);
}

static void iommu_flush_iotlb_psi(struct intel_iommu *iommu, u16 did,
                                  unsigned long pfn, unsigned int pages, int ih, int map)
{
        unsigned int mask = ilog2(__roundup_pow_of_two(pages));
        uint64_t addr = (uint64_t)pfn << VTD_PAGE_SHIFT;

        BUG_ON(pages == 0);

        if (ih)
                ih = 1 << 6;
        /*
         * Fallback to domain selective flush if no PSI support or the size is
         * too big.
         * PSI requires page size to be 2 ^ x, and the base address is naturally
         * aligned to the size
         */
        if (!cap_pgsel_inv(iommu->cap) || mask > cap_max_amask_val(iommu->cap))
                iommu->flush.flush_iotlb(iommu, did, 0, 0,
                                                DMA_TLB_DSI_FLUSH);
        else
                iommu->flush.flush_iotlb(iommu, did, addr | ih, mask,
                                                DMA_TLB_PSI_FLUSH);

        /*
         * In caching mode, changes of pages from non-present to present require
         * flush. However, device IOTLB doesn't need to be flushed in this case.
         */
        if (!cap_caching_mode(iommu->cap) || !map)
                iommu_flush_dev_iotlb(iommu->domains[did], addr, mask);
}

static void iommu_disable_protect_mem_regions(struct intel_iommu *iommu)
{
        u32 pmen;
        unsigned long flags;

        raw_spin_lock_irqsave(&iommu->register_lock, flags);
        pmen = readl(iommu->reg + DMAR_PMEN_REG);
        pmen &= ~DMA_PMEN_EPM;
        writel(pmen, iommu->reg + DMAR_PMEN_REG);

        /* wait for the protected region status bit to clear */
        IOMMU_WAIT_OP(iommu, DMAR_PMEN_REG,
                readl, !(pmen & DMA_PMEN_PRS), pmen);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
}

static void iommu_enable_translation(struct intel_iommu *iommu)
{
        u32 sts;
        unsigned long flags;

        raw_spin_lock_irqsave(&iommu->register_lock, flags);
        iommu->gcmd |= DMA_GCMD_TE;
        writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (sts & DMA_GSTS_TES), sts);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
}

static void iommu_disable_translation(struct intel_iommu *iommu)
{
        u32 sts;
        unsigned long flag;

        raw_spin_lock_irqsave(&iommu->register_lock, flag);
        iommu->gcmd &= ~DMA_GCMD_TE;
        writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);

        /* Make sure hardware complete it */
        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (!(sts & DMA_GSTS_TES)), sts);

        raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
}


static int iommu_init_domains(struct intel_iommu *iommu)
{
        unsigned long ndomains;
        unsigned long nlongs;

        ndomains = cap_ndoms(iommu->cap);
        pr_debug("IOMMU%d: Number of Domains supported <%ld>\n",
                 iommu->seq_id, ndomains);
        nlongs = BITS_TO_LONGS(ndomains);

        spin_lock_init(&iommu->lock);

        /* TBD: there might be 64K domains,
         * consider other allocation for future chip
         */
        iommu->domain_ids = kcalloc(nlongs, sizeof(unsigned long), GFP_KERNEL);
        if (!iommu->domain_ids) {
                pr_err("IOMMU%d: allocating domain id array failed\n",
                       iommu->seq_id);
                return -ENOMEM;
        }
        iommu->domains = kcalloc(ndomains, sizeof(struct dmar_domain *),
                        GFP_KERNEL);
        if (!iommu->domains) {
                pr_err("IOMMU%d: allocating domain array failed\n",
                       iommu->seq_id);
                kfree(iommu->domain_ids);
                iommu->domain_ids = NULL;
                return -ENOMEM;
        }

        /*
         * if Caching mode is set, then invalid translations are tagged
         * with domainid 0. Hence we need to pre-allocate it.
         */
        if (cap_caching_mode(iommu->cap))
                set_bit(0, iommu->domain_ids);
        return 0;
}

static void free_dmar_iommu(struct intel_iommu *iommu)
{
        struct dmar_domain *domain;
        int i;

        if ((iommu->domains) && (iommu->domain_ids)) {
                for_each_set_bit(i, iommu->domain_ids, cap_ndoms(iommu->cap)) {
                        /*
                         * Domain id 0 is reserved for invalid translation
                         * if hardware supports caching mode.
                         */
                        if (cap_caching_mode(iommu->cap) && i == 0)
                                continue;

                        domain = iommu->domains[i];
                        clear_bit(i, iommu->domain_ids);
                        if (domain_detach_iommu(domain, iommu) == 0 &&
                            !domain_type_is_vm(domain))
                                domain_exit(domain);
                }
        }

        if (iommu->gcmd & DMA_GCMD_TE)
                iommu_disable_translation(iommu);

        kfree(iommu->domains);
        kfree(iommu->domain_ids);
        iommu->domains = NULL;
        iommu->domain_ids = NULL;

        g_iommus[iommu->seq_id] = NULL;

        /* free context mapping */
        free_context_table(iommu);
}

static struct dmar_domain *alloc_domain(int flags)
{
        /* domain id for virtual machine, it won't be set in context */
        static atomic_t vm_domid = ATOMIC_INIT(0);
        struct dmar_domain *domain;

        domain = alloc_domain_mem();
        if (!domain)
                return NULL;

        memset(domain, 0, sizeof(*domain));
        domain->nid = -1;
        domain->flags = flags;
        spin_lock_init(&domain->iommu_lock);
        INIT_LIST_HEAD(&domain->devices);
        if (flags & DOMAIN_FLAG_VIRTUAL_MACHINE)
                domain->id = atomic_inc_return(&vm_domid);

        return domain;
}

static int __iommu_attach_domain(struct dmar_domain *domain,
                                 struct intel_iommu *iommu)
{
        int num;
        unsigned long ndomains;

        ndomains = cap_ndoms(iommu->cap);
        num = find_first_zero_bit(iommu->domain_ids, ndomains);
        if (num < ndomains) {
                set_bit(num, iommu->domain_ids);
                iommu->domains[num] = domain;
        } else {
                num = -ENOSPC;
        }

        return num;
}

static int iommu_attach_domain(struct dmar_domain *domain,
                               struct intel_iommu *iommu)
{
        int num;
        unsigned long flags;

        spin_lock_irqsave(&iommu->lock, flags);
        num = __iommu_attach_domain(domain, iommu);
        spin_unlock_irqrestore(&iommu->lock, flags);
        if (num < 0)
                pr_err("IOMMU: no free domain ids\n");

        return num;
}

static int iommu_attach_vm_domain(struct dmar_domain *domain,
                                  struct intel_iommu *iommu)
{
        int num;
        unsigned long ndomains;

        ndomains = cap_ndoms(iommu->cap);
        for_each_set_bit(num, iommu->domain_ids, ndomains)
                if (iommu->domains[num] == domain)
                        return num;

        return __iommu_attach_domain(domain, iommu);
}

static void iommu_detach_domain(struct dmar_domain *domain,
                                struct intel_iommu *iommu)
{
        unsigned long flags;
        int num, ndomains;

        spin_lock_irqsave(&iommu->lock, flags);
        if (domain_type_is_vm_or_si(domain)) {
                ndomains = cap_ndoms(iommu->cap);
                for_each_set_bit(num, iommu->domain_ids, ndomains) {
                        if (iommu->domains[num] == domain) {
                                clear_bit(num, iommu->domain_ids);
                                iommu->domains[num] = NULL;
                                break;
                        }
                }
        } else {
                clear_bit(domain->id, iommu->domain_ids);
                iommu->domains[domain->id] = NULL;
        }
        spin_unlock_irqrestore(&iommu->lock, flags);
}

static void domain_attach_iommu(struct dmar_domain *domain,
                               struct intel_iommu *iommu)
{
        unsigned long flags;

        spin_lock_irqsave(&domain->iommu_lock, flags);
        if (!test_and_set_bit(iommu->seq_id, domain->iommu_bmp)) {
                domain->iommu_count++;
                if (domain->iommu_count == 1)
                        domain->nid = iommu->node;
                domain_update_iommu_cap(domain);
        }
        spin_unlock_irqrestore(&domain->iommu_lock, flags);
}

static int domain_detach_iommu(struct dmar_domain *domain,
                               struct intel_iommu *iommu)
{
        unsigned long flags;
        int count = INT_MAX;

        spin_lock_irqsave(&domain->iommu_lock, flags);
        if (test_and_clear_bit(iommu->seq_id, domain->iommu_bmp)) {
                count = --domain->iommu_count;
                domain_update_iommu_cap(domain);
        }
        spin_unlock_irqrestore(&domain->iommu_lock, flags);

        return count;
}

static struct iova_domain reserved_iova_list;
static struct lock_class_key reserved_rbtree_key;

static int dmar_init_reserved_ranges(void)
{
        struct pci_dev *pdev = NULL;
        struct iova *iova;
        int i;

        init_iova_domain(&reserved_iova_list, DMA_32BIT_PFN);

        lockdep_set_class(&reserved_iova_list.iova_rbtree_lock,
                &reserved_rbtree_key);

        /* IOAPIC ranges shouldn't be accessed by DMA */
        iova = reserve_iova(&reserved_iova_list, IOVA_PFN(IOAPIC_RANGE_START),
                IOVA_PFN(IOAPIC_RANGE_END));
        if (!iova) {
                printk(KERN_ERR "Reserve IOAPIC range failed\n");
                return -ENODEV;
        }

        /* Reserve all PCI MMIO to avoid peer-to-peer access */
        for_each_pci_dev(pdev) {
                struct resource *r;

                for (i = 0; i < PCI_NUM_RESOURCES; i++) {
                        r = &pdev->resource[i];
                        if (!r->flags || !(r->flags & IORESOURCE_MEM))
                                continue;
                        iova = reserve_iova(&reserved_iova_list,
                                            IOVA_PFN(r->start),
                                            IOVA_PFN(r->end));
                        if (!iova) {
                                printk(KERN_ERR "Reserve iova failed\n");
                                return -ENODEV;
                        }
                }
        }
        return 0;
}

static void domain_reserve_special_ranges(struct dmar_domain *domain)
{
        copy_reserved_iova(&reserved_iova_list, &domain->iovad);
}

static inline int guestwidth_to_adjustwidth(int gaw)
{
        int agaw;
        int r = (gaw - 12) % 9;

        if (r == 0)
                agaw = gaw;
        else
                agaw = gaw + 9 - r;
        if (agaw > 64)
                agaw = 64;
        return agaw;
}

static int domain_init(struct dmar_domain *domain, int guest_width)
{
        struct intel_iommu *iommu;
        int adjust_width, agaw;
        unsigned long sagaw;

        init_iova_domain(&domain->iovad, DMA_32BIT_PFN);
        domain_reserve_special_ranges(domain);

        /* calculate AGAW */
        iommu = domain_get_iommu(domain);
        if (guest_width > cap_mgaw(iommu->cap))
                guest_width = cap_mgaw(iommu->cap);
        domain->gaw = guest_width;
        adjust_width = guestwidth_to_adjustwidth(guest_width);
        agaw = width_to_agaw(adjust_width);
        sagaw = cap_sagaw(iommu->cap);
        if (!test_bit(agaw, &sagaw)) {
                /* hardware doesn't support it, choose a bigger one */
                pr_debug("IOMMU: hardware doesn't support agaw %d\n", agaw);
                agaw = find_next_bit(&sagaw, 5, agaw);
                if (agaw >= 5)
                        return -ENODEV;
        }
        domain->agaw = agaw;

        if (ecap_coherent(iommu->ecap))
                domain->iommu_coherency = 1;
        else
                domain->iommu_coherency = 0;

        if (ecap_sc_support(iommu->ecap))
                domain->iommu_snooping = 1;
        else
                domain->iommu_snooping = 0;

        if (intel_iommu_superpage)
                domain->iommu_superpage = fls(cap_super_page_val(iommu->cap));
        else
                domain->iommu_superpage = 0;

        domain->nid = iommu->node;

        /* always allocate the top pgd */
        domain->pgd = (struct dma_pte *)alloc_pgtable_page(domain->nid);
        if (!domain->pgd)
                return -ENOMEM;
        __iommu_flush_cache(iommu, domain->pgd, PAGE_SIZE);
        return 0;
}

static void domain_exit(struct dmar_domain *domain)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        struct page *freelist = NULL;

        /* Domain 0 is reserved, so dont process it */
        if (!domain)
                return;

        /* Flush any lazy unmaps that may reference this domain */
        if (!intel_iommu_strict)
                flush_unmaps_timeout(0);

        /* remove associated devices */
        domain_remove_dev_info(domain);

        /* destroy iovas */
        put_iova_domain(&domain->iovad);

        freelist = domain_unmap(domain, 0, DOMAIN_MAX_PFN(domain->gaw));

        /* clear attached or cached domains */
        rcu_read_lock();
        for_each_active_iommu(iommu, drhd)
                iommu_detach_domain(domain, iommu);
        rcu_read_unlock();

        dma_free_pagelist(freelist);

        free_domain_mem(domain);
}

static int domain_context_mapping_one(struct dmar_domain *domain,
                                      struct intel_iommu *iommu,
                                      u8 bus, u8 devfn, int translation)
{
        struct context_entry *context;
        unsigned long flags;
        struct dma_pte *pgd;
        int id;
        int agaw;
        struct device_domain_info *info = NULL;

        pr_debug("Set context mapping for %02x:%02x.%d\n",
                bus, PCI_SLOT(devfn), PCI_FUNC(devfn));

        BUG_ON(!domain->pgd);
        BUG_ON(translation != CONTEXT_TT_PASS_THROUGH &&
               translation != CONTEXT_TT_MULTI_LEVEL);

        context = device_to_context_entry(iommu, bus, devfn);
        if (!context)
                return -ENOMEM;
        spin_lock_irqsave(&iommu->lock, flags);
        if (context_present(context)) {
                spin_unlock_irqrestore(&iommu->lock, flags);
                return 0;
        }

        id = domain->id;
        pgd = domain->pgd;

        if (domain_type_is_vm_or_si(domain)) {
                if (domain_type_is_vm(domain)) {
                        id = iommu_attach_vm_domain(domain, iommu);
                        if (id < 0) {
                                spin_unlock_irqrestore(&iommu->lock, flags);
                                pr_err("IOMMU: no free domain ids\n");
                                return -EFAULT;
                        }
                }

                /* Skip top levels of page tables for
                 * iommu which has less agaw than default.
                 * Unnecessary for PT mode.
                 */
                if (translation != CONTEXT_TT_PASS_THROUGH) {
                        for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
                                pgd = phys_to_virt(dma_pte_addr(pgd));
                                if (!dma_pte_present(pgd)) {
                                        spin_unlock_irqrestore(&iommu->lock, flags);
                                        return -ENOMEM;
                                }
                        }
                }
        }

        context_set_domain_id(context, id);

        if (translation != CONTEXT_TT_PASS_THROUGH) {
                info = iommu_support_dev_iotlb(domain, iommu, bus, devfn);
                translation = info ? CONTEXT_TT_DEV_IOTLB :
                                     CONTEXT_TT_MULTI_LEVEL;
        }
        /*
         * In pass through mode, AW must be programmed to indicate the largest
         * AGAW value supported by hardware. And ASR is ignored by hardware.
         */
        if (unlikely(translation == CONTEXT_TT_PASS_THROUGH))
                context_set_address_width(context, iommu->msagaw);
        else {
                context_set_address_root(context, virt_to_phys(pgd));
                context_set_address_width(context, iommu->agaw);
        }

        context_set_translation_type(context, translation);
        context_set_fault_enable(context);
        context_set_present(context);
        domain_flush_cache(domain, context, sizeof(*context));

        /*
         * It's a non-present to present mapping. If hardware doesn't cache
         * non-present entry we only need to flush the write-buffer. If the
         * _does_ cache non-present entries, then it does so in the special
         * domain #0, which we have to flush:
         */
        if (cap_caching_mode(iommu->cap)) {
                iommu->flush.flush_context(iommu, 0,
                                           (((u16)bus) << 8) | devfn,
                                           DMA_CCMD_MASK_NOBIT,
                                           DMA_CCMD_DEVICE_INVL);
                iommu->flush.flush_iotlb(iommu, id, 0, 0, DMA_TLB_DSI_FLUSH);
        } else {
                iommu_flush_write_buffer(iommu);
        }
        iommu_enable_dev_iotlb(info);
        spin_unlock_irqrestore(&iommu->lock, flags);

        domain_attach_iommu(domain, iommu);

        return 0;
}

struct domain_context_mapping_data {
        struct dmar_domain *domain;
        struct intel_iommu *iommu;
        int translation;
};

static int domain_context_mapping_cb(struct pci_dev *pdev,
                                     u16 alias, void *opaque)
{
        struct domain_context_mapping_data *data = opaque;

        return domain_context_mapping_one(data->domain, data->iommu,
                                          PCI_BUS_NUM(alias), alias & 0xff,
                                          data->translation);
}

static int
domain_context_mapping(struct dmar_domain *domain, struct device *dev,
                       int translation)
{
        struct intel_iommu *iommu;
        u8 bus, devfn;
        struct domain_context_mapping_data data;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return -ENODEV;

        if (!dev_is_pci(dev))
                return domain_context_mapping_one(domain, iommu, bus, devfn,
                                                  translation);

        data.domain = domain;
        data.iommu = iommu;
        data.translation = translation;

        return pci_for_each_dma_alias(to_pci_dev(dev),
                                      &domain_context_mapping_cb, &data);
}

static int domain_context_mapped_cb(struct pci_dev *pdev,
                                    u16 alias, void *opaque)
{
        struct intel_iommu *iommu = opaque;

        return !device_context_mapped(iommu, PCI_BUS_NUM(alias), alias & 0xff);
}

static int domain_context_mapped(struct device *dev)
{
        struct intel_iommu *iommu;
        u8 bus, devfn;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return -ENODEV;

        if (!dev_is_pci(dev))
                return device_context_mapped(iommu, bus, devfn);

        return !pci_for_each_dma_alias(to_pci_dev(dev),
                                       domain_context_mapped_cb, iommu);
}

/* Returns a number of VTD pages, but aligned to MM page size */
static inline unsigned long aligned_nrpages(unsigned long host_addr,
                                            size_t size)
{
        host_addr &= ~PAGE_MASK;
        return PAGE_ALIGN(host_addr + size) >> VTD_PAGE_SHIFT;
}

/* Return largest possible superpage level for a given mapping */
static inline int hardware_largepage_caps(struct dmar_domain *domain,
                                          unsigned long iov_pfn,
                                          unsigned long phy_pfn,
                                          unsigned long pages)
{
        int support, level = 1;
        unsigned long pfnmerge;

        support = domain->iommu_superpage;

        /* To use a large page, the virtual *and* physical addresses
           must be aligned to 2MiB/1GiB/etc. Lower bits set in either
           of them will mean we have to use smaller pages. So just
           merge them and check both at once. */
        pfnmerge = iov_pfn | phy_pfn;

        while (support && !(pfnmerge & ~VTD_STRIDE_MASK)) {
                pages >>= VTD_STRIDE_SHIFT;
                if (!pages)
                        break;
                pfnmerge >>= VTD_STRIDE_SHIFT;
                level++;
                support--;
        }
        return level;
}

static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                            struct scatterlist *sg, unsigned long phys_pfn,
                            unsigned long nr_pages, int prot)
{
        struct dma_pte *first_pte = NULL, *pte = NULL;
        phys_addr_t uninitialized_var(pteval);
        unsigned long sg_res;
        unsigned int largepage_lvl = 0;
        unsigned long lvl_pages = 0;

        BUG_ON(!domain_pfn_supported(domain, iov_pfn + nr_pages - 1));

        if ((prot & (DMA_PTE_READ|DMA_PTE_WRITE)) == 0)
                return -EINVAL;

        prot &= DMA_PTE_READ | DMA_PTE_WRITE | DMA_PTE_SNP;

        if (sg)
                sg_res = 0;
        else {
                sg_res = nr_pages + 1;
                pteval = ((phys_addr_t)phys_pfn << VTD_PAGE_SHIFT) | prot;
        }

        while (nr_pages > 0) {
                uint64_t tmp;

                if (!sg_res) {
                        sg_res = aligned_nrpages(sg->offset, sg->length);
                        sg->dma_address = ((dma_addr_t)iov_pfn << VTD_PAGE_SHIFT) + sg->offset;
                        sg->dma_length = sg->length;
                        pteval = page_to_phys(sg_page(sg)) | prot;
                        phys_pfn = pteval >> VTD_PAGE_SHIFT;
                }

                if (!pte) {
                        largepage_lvl = hardware_largepage_caps(domain, iov_pfn, phys_pfn, sg_res);

                        first_pte = pte = pfn_to_dma_pte(domain, iov_pfn, &largepage_lvl);
                        if (!pte)
                                return -ENOMEM;
                        /* It is large page*/
                        if (largepage_lvl > 1) {
                                pteval |= DMA_PTE_LARGE_PAGE;
                                lvl_pages = lvl_to_nr_pages(largepage_lvl);
                                /*
                                 * Ensure that old small page tables are
                                 * removed to make room for superpage,
                                 * if they exist.
                                 */
                                dma_pte_free_pagetable(domain, iov_pfn,
                                                       iov_pfn + lvl_pages - 1);
                        } else {
                                pteval &= ~(uint64_t)DMA_PTE_LARGE_PAGE;
                        }

                }
                /* We don't need lock here, nobody else
                 * touches the iova range
                 */
                tmp = cmpxchg64_local(&pte->val, 0ULL, pteval);
                if (tmp) {
                        static int dumps = 5;
                        printk(KERN_CRIT "ERROR: DMA PTE for vPFN 0x%lx already set (to %llx not %llx)\n",
                               iov_pfn, tmp, (unsigned long long)pteval);
                        if (dumps) {
                                dumps--;
                                debug_dma_dump_mappings(NULL);
                        }
                        WARN_ON(1);
                }

                lvl_pages = lvl_to_nr_pages(largepage_lvl);

                BUG_ON(nr_pages < lvl_pages);
                BUG_ON(sg_res < lvl_pages);

                nr_pages -= lvl_pages;
                iov_pfn += lvl_pages;
                phys_pfn += lvl_pages;
                pteval += lvl_pages * VTD_PAGE_SIZE;
                sg_res -= lvl_pages;

                /* If the next PTE would be the first in a new page, then we
                   need to flush the cache on the entries we've just written.
                   And then we'll need to recalculate 'pte', so clear it and
                   let it get set again in the if (!pte) block above.

                   If we're done (!nr_pages) we need to flush the cache too.

                   Also if we've been setting superpages, we may need to
                   recalculate 'pte' and switch back to smaller pages for the
                   end of the mapping, if the trailing size is not enough to
                   use another superpage (i.e. sg_res < lvl_pages). */
                pte++;
                if (!nr_pages || first_pte_in_page(pte) ||
                    (largepage_lvl > 1 && sg_res < lvl_pages)) {
                        domain_flush_cache(domain, first_pte,
                                           (void *)pte - (void *)first_pte);
                        pte = NULL;
                }

                if (!sg_res && nr_pages)
                        sg = sg_next(sg);
        }
        return 0;
}

static inline int domain_sg_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                                    struct scatterlist *sg, unsigned long nr_pages,
                                    int prot)
{
        return __domain_mapping(domain, iov_pfn, sg, 0, nr_pages, prot);
}

static inline int domain_pfn_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
                                     unsigned long phys_pfn, unsigned long nr_pages,
                                     int prot)
{
        return __domain_mapping(domain, iov_pfn, NULL, phys_pfn, nr_pages, prot);
}

static void iommu_detach_dev(struct intel_iommu *iommu, u8 bus, u8 devfn)
{
        if (!iommu)
                return;

        clear_context_table(iommu, bus, devfn);
        iommu->flush.flush_context(iommu, 0, 0, 0,
                                           DMA_CCMD_GLOBAL_INVL);
        iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
}

static inline void unlink_domain_info(struct device_domain_info *info)
{
        assert_spin_locked(&device_domain_lock);
        list_del(&info->link);
        list_del(&info->global);
        if (info->dev)
                info->dev->archdata.iommu = NULL;
}

static void domain_remove_dev_info(struct dmar_domain *domain)
{
        struct device_domain_info *info, *tmp;
        unsigned long flags;

        spin_lock_irqsave(&device_domain_lock, flags);
        list_for_each_entry_safe(info, tmp, &domain->devices, link) {
                unlink_domain_info(info);
                spin_unlock_irqrestore(&device_domain_lock, flags);

                iommu_disable_dev_iotlb(info);
                iommu_detach_dev(info->iommu, info->bus, info->devfn);

                if (domain_type_is_vm(domain)) {
                        iommu_detach_dependent_devices(info->iommu, info->dev);
                        domain_detach_iommu(domain, info->iommu);
                }

                free_devinfo_mem(info);
                spin_lock_irqsave(&device_domain_lock, flags);
        }
        spin_unlock_irqrestore(&device_domain_lock, flags);
}

/*
 * find_domain
 * Note: we use struct device->archdata.iommu stores the info
 */
static struct dmar_domain *find_domain(struct device *dev)
{
        struct device_domain_info *info;

        /* No lock here, assumes no domain exit in normal case */
        info = dev->archdata.iommu;
        if (info)
                return info->domain;
        return NULL;
}

static inline struct device_domain_info *
dmar_search_domain_by_dev_info(int segment, int bus, int devfn)
{
        struct device_domain_info *info;

        list_for_each_entry(info, &device_domain_list, global)
                if (info->iommu->segment == segment && info->bus == bus &&
                    info->devfn == devfn)
                        return info;

        return NULL;
}

static struct dmar_domain *dmar_insert_dev_info(struct intel_iommu *iommu,
                                                int bus, int devfn,
                                                struct device *dev,
                                                struct dmar_domain *domain)
{
        struct dmar_domain *found = NULL;
        struct device_domain_info *info;
        unsigned long flags;

        info = alloc_devinfo_mem();
        if (!info)
                return NULL;

        info->bus = bus;
        info->devfn = devfn;
        info->dev = dev;
        info->domain = domain;
        info->iommu = iommu;

        spin_lock_irqsave(&device_domain_lock, flags);
        if (dev)
                found = find_domain(dev);
        else {
                struct device_domain_info *info2;
                info2 = dmar_search_domain_by_dev_info(iommu->segment, bus, devfn);
                if (info2)
                        found = info2->domain;
        }
        if (found) {
                spin_unlock_irqrestore(&device_domain_lock, flags);
                free_devinfo_mem(info);
                /* Caller must free the original domain */
                return found;
        }

        list_add(&info->link, &domain->devices);
        list_add(&info->global, &device_domain_list);
        if (dev)
                dev->archdata.iommu = info;
        spin_unlock_irqrestore(&device_domain_lock, flags);

        return domain;
}

static int get_last_alias(struct pci_dev *pdev, u16 alias, void *opaque)
{
        *(u16 *)opaque = alias;
        return 0;
}

/* domain is initialized */
static struct dmar_domain *get_domain_for_dev(struct device *dev, int gaw)
{
        struct dmar_domain *domain, *tmp;
        struct intel_iommu *iommu;
        struct device_domain_info *info;
        u16 dma_alias;
        unsigned long flags;
        u8 bus, devfn;

        domain = find_domain(dev);
        if (domain)
                return domain;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return NULL;

        if (dev_is_pci(dev)) {
                struct pci_dev *pdev = to_pci_dev(dev);

                pci_for_each_dma_alias(pdev, get_last_alias, &dma_alias);

                spin_lock_irqsave(&device_domain_lock, flags);
                info = dmar_search_domain_by_dev_info(pci_domain_nr(pdev->bus),
                                                      PCI_BUS_NUM(dma_alias),
                                                      dma_alias & 0xff);
                if (info) {
                        iommu = info->iommu;
                        domain = info->domain;
                }
                spin_unlock_irqrestore(&device_domain_lock, flags);

                /* DMA alias already has a domain, uses it */
                if (info)
                        goto found_domain;
        }

        /* Allocate and initialize new domain for the device */
        domain = alloc_domain(0);
        if (!domain)
                return NULL;
        domain->id = iommu_attach_domain(domain, iommu);
        if (domain->id < 0) {
                free_domain_mem(domain);
                return NULL;
        }
        domain_attach_iommu(domain, iommu);
        if (domain_init(domain, gaw)) {
                domain_exit(domain);
                return NULL;
        }

        /* register PCI DMA alias device */
        if (dev_is_pci(dev)) {
                tmp = dmar_insert_dev_info(iommu, PCI_BUS_NUM(dma_alias),
                                           dma_alias & 0xff, NULL, domain);

                if (!tmp || tmp != domain) {
                        domain_exit(domain);
                        domain = tmp;
                }

                if (!domain)
                        return NULL;
        }

found_domain:
        tmp = dmar_insert_dev_info(iommu, bus, devfn, dev, domain);

        if (!tmp || tmp != domain) {
                domain_exit(domain);
                domain = tmp;
        }

        return domain;
}

static int iommu_identity_mapping;
#define IDENTMAP_ALL            1
#define IDENTMAP_GFX            2
#define IDENTMAP_AZALIA         4

static int iommu_domain_identity_map(struct dmar_domain *domain,
                                     unsigned long long start,
                                     unsigned long long end)
{
        unsigned long first_vpfn = start >> VTD_PAGE_SHIFT;
        unsigned long last_vpfn = end >> VTD_PAGE_SHIFT;

        if (!reserve_iova(&domain->iovad, dma_to_mm_pfn(first_vpfn),
                          dma_to_mm_pfn(last_vpfn))) {
                printk(KERN_ERR "IOMMU: reserve iova failed\n");
                return -ENOMEM;
        }

        pr_debug("Mapping reserved region %llx-%llx for domain %d\n",
                 start, end, domain->id);
        /*
         * RMRR range might have overlap with physical memory range,
         * clear it first
         */
        dma_pte_clear_range(domain, first_vpfn, last_vpfn);

        return domain_pfn_mapping(domain, first_vpfn, first_vpfn,
                                  last_vpfn - first_vpfn + 1,
                                  DMA_PTE_READ|DMA_PTE_WRITE);
}

static int iommu_prepare_identity_map(struct device *dev,
                                      unsigned long long start,
                                      unsigned long long end)
{
        struct dmar_domain *domain;
        int ret;

        domain = get_domain_for_dev(dev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
        if (!domain)
                return -ENOMEM;

        /* For _hardware_ passthrough, don't bother. But for software
           passthrough, we do it anyway -- it may indicate a memory
           range which is reserved in E820, so which didn't get set
           up to start with in si_domain */
        if (domain == si_domain && hw_pass_through) {
                printk("Ignoring identity map for HW passthrough device %s [0x%Lx - 0x%Lx]\n",
                       dev_name(dev), start, end);
                return 0;
        }

        printk(KERN_INFO
               "IOMMU: Setting identity map for device %s [0x%Lx - 0x%Lx]\n",
               dev_name(dev), start, end);
        
        if (end < start) {
                WARN(1, "Your BIOS is broken; RMRR ends before it starts!\n"
                        "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
                        dmi_get_system_info(DMI_BIOS_VENDOR),
                        dmi_get_system_info(DMI_BIOS_VERSION),
                     dmi_get_system_info(DMI_PRODUCT_VERSION));
                ret = -EIO;
                goto error;
        }

        if (end >> agaw_to_width(domain->agaw)) {
                WARN(1, "Your BIOS is broken; RMRR exceeds permitted address width (%d bits)\n"
                     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
                     agaw_to_width(domain->agaw),
                     dmi_get_system_info(DMI_BIOS_VENDOR),
                     dmi_get_system_info(DMI_BIOS_VERSION),
                     dmi_get_system_info(DMI_PRODUCT_VERSION));
                ret = -EIO;
                goto error;
        }

        ret = iommu_domain_identity_map(domain, start, end);
        if (ret)
                goto error;

        /* context entry init */
        ret = domain_context_mapping(domain, dev, CONTEXT_TT_MULTI_LEVEL);
        if (ret)
                goto error;

        return 0;

 error:
        domain_exit(domain);
        return ret;
}

static inline int iommu_prepare_rmrr_dev(struct dmar_rmrr_unit *rmrr,
                                         struct device *dev)
{
        if (dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO)
                return 0;
        return iommu_prepare_identity_map(dev, rmrr->base_address,
                                          rmrr->end_address);
}

#ifdef CONFIG_INTEL_IOMMU_FLOPPY_WA
static inline void iommu_prepare_isa(void)
{
        struct pci_dev *pdev;
        int ret;

        pdev = pci_get_class(PCI_CLASS_BRIDGE_ISA << 8, NULL);
        if (!pdev)
                return;

        printk(KERN_INFO "IOMMU: Prepare 0-16MiB unity mapping for LPC\n");
        ret = iommu_prepare_identity_map(&pdev->dev, 0, 16*1024*1024 - 1);

        if (ret)
                printk(KERN_ERR "IOMMU: Failed to create 0-16MiB identity map; "
                       "floppy might not work\n");

        pci_dev_put(pdev);
}
#else
static inline void iommu_prepare_isa(void)
{
        return;
}
#endif /* !CONFIG_INTEL_IOMMU_FLPY_WA */

static int md_domain_init(struct dmar_domain *domain, int guest_width);

static int __init si_domain_init(int hw)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int nid, ret = 0;
        bool first = true;

        si_domain = alloc_domain(DOMAIN_FLAG_STATIC_IDENTITY);
        if (!si_domain)
                return -EFAULT;

        for_each_active_iommu(iommu, drhd) {
                ret = iommu_attach_domain(si_domain, iommu);
                if (ret < 0) {
                        domain_exit(si_domain);
                        return -EFAULT;
                } else if (first) {
                        si_domain->id = ret;
                        first = false;
                } else if (si_domain->id != ret) {
                        domain_exit(si_domain);
                        return -EFAULT;
                }
                domain_attach_iommu(si_domain, iommu);
        }

        if (md_domain_init(si_domain, DEFAULT_DOMAIN_ADDRESS_WIDTH)) {
                domain_exit(si_domain);
                return -EFAULT;
        }

        pr_debug("IOMMU: identity mapping domain is domain %d\n",
                 si_domain->id);

        if (hw)
                return 0;

        for_each_online_node(nid) {
                unsigned long start_pfn, end_pfn;
                int i;

                for_each_mem_pfn_range(i, nid, &start_pfn, &end_pfn, NULL) {
                        ret = iommu_domain_identity_map(si_domain,
                                        PFN_PHYS(start_pfn), PFN_PHYS(end_pfn));
                        if (ret)
                                return ret;
                }
        }

        return 0;
}

static int identity_mapping(struct device *dev)
{
        struct device_domain_info *info;

        if (likely(!iommu_identity_mapping))
                return 0;

        info = dev->archdata.iommu;
        if (info && info != DUMMY_DEVICE_DOMAIN_INFO)
                return (info->domain == si_domain);

        return 0;
}

static int domain_add_dev_info(struct dmar_domain *domain,
                               struct device *dev, int translation)
{
        struct dmar_domain *ndomain;
        struct intel_iommu *iommu;
        u8 bus, devfn;
        int ret;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return -ENODEV;

        ndomain = dmar_insert_dev_info(iommu, bus, devfn, dev, domain);
        if (ndomain != domain)
                return -EBUSY;

        ret = domain_context_mapping(domain, dev, translation);
        if (ret) {
                domain_remove_one_dev_info(domain, dev);
                return ret;
        }

        return 0;
}

static bool device_has_rmrr(struct device *dev)
{
        struct dmar_rmrr_unit *rmrr;
        struct device *tmp;
        int i;

        rcu_read_lock();
        for_each_rmrr_units(rmrr) {
                /*
                 * Return TRUE if this RMRR contains the device that
                 * is passed in.
                 */
                for_each_active_dev_scope(rmrr->devices,
                                          rmrr->devices_cnt, i, tmp)
                        if (tmp == dev) {
                                rcu_read_unlock();
                                return true;
                        }
        }
        rcu_read_unlock();
        return false;
}

/*
 * There are a couple cases where we need to restrict the functionality of
 * devices associated with RMRRs.  The first is when evaluating a device for
 * identity mapping because problems exist when devices are moved in and out
 * of domains and their respective RMRR information is lost.  This means that
 * a device with associated RMRRs will never be in a "passthrough" domain.
 * The second is use of the device through the IOMMU API.  This interface
 * expects to have full control of the IOVA space for the device.  We cannot
 * satisfy both the requirement that RMRR access is maintained and have an
 * unencumbered IOVA space.  We also have no ability to quiesce the device's
 * use of the RMRR space or even inform the IOMMU API user of the restriction.
 * We therefore prevent devices associated with an RMRR from participating in
 * the IOMMU API, which eliminates them from device assignment.
 *
 * In both cases we assume that PCI USB devices with RMRRs have them largely
 * for historical reasons and that the RMRR space is not actively used post
 * boot.  This exclusion may change if vendors begin to abuse it.
 */
static bool device_is_rmrr_locked(struct device *dev)
{
        if (!device_has_rmrr(dev))
                return false;

        if (dev_is_pci(dev)) {
                struct pci_dev *pdev = to_pci_dev(dev);

                if ((pdev->class >> 8) == PCI_CLASS_SERIAL_USB)
                        return false;
        }

        return true;
}

static int iommu_should_identity_map(struct device *dev, int startup)
{

        if (dev_is_pci(dev)) {
                struct pci_dev *pdev = to_pci_dev(dev);

                if (device_is_rmrr_locked(dev))
                        return 0;

                if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev))
                        return 1;

                if ((iommu_identity_mapping & IDENTMAP_GFX) && IS_GFX_DEVICE(pdev))
                        return 1;

                if (!(iommu_identity_mapping & IDENTMAP_ALL))
                        return 0;

                /*
                 * We want to start off with all devices in the 1:1 domain, and
                 * take them out later if we find they can't access all of memory.
                 *
                 * However, we can't do this for PCI devices behind bridges,
                 * because all PCI devices behind the same bridge will end up
                 * with the same source-id on their transactions.
                 *
                 * Practically speaking, we can't change things around for these
                 * devices at run-time, because we can't be sure there'll be no
                 * DMA transactions in flight for any of their siblings.
                 *
                 * So PCI devices (unless they're on the root bus) as well as
                 * their parent PCI-PCI or PCIe-PCI bridges must be left _out_ of
                 * the 1:1 domain, just in _case_ one of their siblings turns out
                 * not to be able to map all of memory.
                 */
                if (!pci_is_pcie(pdev)) {
                        if (!pci_is_root_bus(pdev->bus))
                                return 0;
                        if (pdev->class >> 8 == PCI_CLASS_BRIDGE_PCI)
                                return 0;
                } else if (pci_pcie_type(pdev) == PCI_EXP_TYPE_PCI_BRIDGE)
                        return 0;
        } else {
                if (device_has_rmrr(dev))
                        return 0;
        }

        /*
         * At boot time, we don't yet know if devices will be 64-bit capable.
         * Assume that they will — if they turn out not to be, then we can
         * take them out of the 1:1 domain later.
         */
        if (!startup) {
                /*
                 * If the device's dma_mask is less than the system's memory
                 * size then this is not a candidate for identity mapping.
                 */
                u64 dma_mask = *dev->dma_mask;

                if (dev->coherent_dma_mask &&
                    dev->coherent_dma_mask < dma_mask)
                        dma_mask = dev->coherent_dma_mask;

                return dma_mask >= dma_get_required_mask(dev);
        }

        return 1;
}

static int __init dev_prepare_static_identity_mapping(struct device *dev, int hw)
{
        int ret;

        if (!iommu_should_identity_map(dev, 1))
                return 0;

        ret = domain_add_dev_info(si_domain, dev,
                                  hw ? CONTEXT_TT_PASS_THROUGH :
                                       CONTEXT_TT_MULTI_LEVEL);
        if (!ret)
                pr_info("IOMMU: %s identity mapping for device %s\n",
                        hw ? "hardware" : "software", dev_name(dev));
        else if (ret == -ENODEV)
                /* device not associated with an iommu */
                ret = 0;

        return ret;
}


static int __init iommu_prepare_static_identity_mapping(int hw)
{
        struct pci_dev *pdev = NULL;
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        struct device *dev;
        int i;
        int ret = 0;

        ret = si_domain_init(hw);
        if (ret)
                return -EFAULT;

        for_each_pci_dev(pdev) {
                ret = dev_prepare_static_identity_mapping(&pdev->dev, hw);
                if (ret)
                        return ret;
        }

        for_each_active_iommu(iommu, drhd)
                for_each_active_dev_scope(drhd->devices, drhd->devices_cnt, i, dev) {
                        struct acpi_device_physical_node *pn;
                        struct acpi_device *adev;

                        if (dev->bus != &acpi_bus_type)
                                continue;
                                
                        adev= to_acpi_device(dev);
                        mutex_lock(&adev->physical_node_lock);
                        list_for_each_entry(pn, &adev->physical_node_list, node) {
                                ret = dev_prepare_static_identity_mapping(pn->dev, hw);
                                if (ret)
                                        break;
                        }
                        mutex_unlock(&adev->physical_node_lock);
                        if (ret)
                                return ret;
                }

        return 0;
}

static int __init init_dmars(void)
{
        struct dmar_drhd_unit *drhd;
        struct dmar_rmrr_unit *rmrr;
        struct device *dev;
        struct intel_iommu *iommu;
        int i, ret;

        /*
         * for each drhd
         *    allocate root
         *    initialize and program root entry to not present
         * endfor
         */
        for_each_drhd_unit(drhd) {
                /*
                 * lock not needed as this is only incremented in the single
                 * threaded kernel __init code path all other access are read
                 * only
                 */
                if (g_num_of_iommus < IOMMU_UNITS_SUPPORTED) {
                        g_num_of_iommus++;
                        continue;
                }
                printk_once(KERN_ERR "intel-iommu: exceeded %d IOMMUs\n",
                          IOMMU_UNITS_SUPPORTED);
        }

        g_iommus = kcalloc(g_num_of_iommus, sizeof(struct intel_iommu *),
                        GFP_KERNEL);
        if (!g_iommus) {
                printk(KERN_ERR "Allocating global iommu array failed\n");
                ret = -ENOMEM;
                goto error;
        }

        deferred_flush = kzalloc(g_num_of_iommus *
                sizeof(struct deferred_flush_tables), GFP_KERNEL);
        if (!deferred_flush) {
                ret = -ENOMEM;
                goto free_g_iommus;
        }

        for_each_active_iommu(iommu, drhd) {
                g_iommus[iommu->seq_id] = iommu;

                ret = iommu_init_domains(iommu);
                if (ret)
                        goto free_iommu;

                /*
                 * TBD:
                 * we could share the same root & context tables
                 * among all IOMMU's. Need to Split it later.
                 */
                ret = iommu_alloc_root_entry(iommu);
                if (ret) {
                        printk(KERN_ERR "IOMMU: allocate root entry failed\n");
                        goto free_iommu;
                }
                if (!ecap_pass_through(iommu->ecap))
                        hw_pass_through = 0;
        }

        /*
         * Start from the sane iommu hardware state.
         */
        for_each_active_iommu(iommu, drhd) {
                /*
                 * If the queued invalidation is already initialized by us
                 * (for example, while enabling interrupt-remapping) then
                 * we got the things already rolling from a sane state.
                 */
                if (iommu->qi)
                        continue;

                /*
                 * Clear any previous faults.
                 */
                dmar_fault(-1, iommu);
                /*
                 * Disable queued invalidation if supported and already enabled
                 * before OS handover.
                 */
                dmar_disable_qi(iommu);
        }

        for_each_active_iommu(iommu, drhd) {
                if (dmar_enable_qi(iommu)) {
                        /*
                         * Queued Invalidate not enabled, use Register Based
                         * Invalidate
                         */
                        iommu->flush.flush_context = __iommu_flush_context;
                        iommu->flush.flush_iotlb = __iommu_flush_iotlb;
                        printk(KERN_INFO "IOMMU %d 0x%Lx: using Register based "
                               "invalidation\n",
                                iommu->seq_id,
                               (unsigned long long)drhd->reg_base_addr);
                } else {
                        iommu->flush.flush_context = qi_flush_context;
                        iommu->flush.flush_iotlb = qi_flush_iotlb;
                        printk(KERN_INFO "IOMMU %d 0x%Lx: using Queued "
                               "invalidation\n",
                                iommu->seq_id,
                               (unsigned long long)drhd->reg_base_addr);
                }
        }

        if (iommu_pass_through)
                iommu_identity_mapping |= IDENTMAP_ALL;

#ifdef CONFIG_INTEL_IOMMU_BROKEN_GFX_WA
        iommu_identity_mapping |= IDENTMAP_GFX;
#endif

        check_tylersburg_isoch();

        /*
         * If pass through is not set or not enabled, setup context entries for
         * identity mappings for rmrr, gfx, and isa and may fall back to static
         * identity mapping if iommu_identity_mapping is set.
         */
        if (iommu_identity_mapping) {
                ret = iommu_prepare_static_identity_mapping(hw_pass_through);
                if (ret) {
                        printk(KERN_CRIT "Failed to setup IOMMU pass-through\n");
                        goto free_iommu;
                }
        }
        /*
         * For each rmrr
         *   for each dev attached to rmrr
         *   do
         *     locate drhd for dev, alloc domain for dev
         *     allocate free domain
         *     allocate page table entries for rmrr
         *     if context not allocated for bus
         *           allocate and init context
         *           set present in root table for this bus
         *     init context with domain, translation etc
         *    endfor
         * endfor
         */
        printk(KERN_INFO "IOMMU: Setting RMRR:\n");
        for_each_rmrr_units(rmrr) {
                /* some BIOS lists non-exist devices in DMAR table. */
                for_each_active_dev_scope(rmrr->devices, rmrr->devices_cnt,
                                          i, dev) {
                        ret = iommu_prepare_rmrr_dev(rmrr, dev);
                        if (ret)
                                printk(KERN_ERR
                                       "IOMMU: mapping reserved region failed\n");
                }
        }

        iommu_prepare_isa();

        /*
         * for each drhd
         *   enable fault log
         *   global invalidate context cache
         *   global invalidate iotlb
         *   enable translation
         */
        for_each_iommu(iommu, drhd) {
                if (drhd->ignored) {
                        /*
                         * we always have to disable PMRs or DMA may fail on
                         * this device
                         */
                        if (force_on)
                                iommu_disable_protect_mem_regions(iommu);
                        continue;
                }

                iommu_flush_write_buffer(iommu);

                ret = dmar_set_interrupt(iommu);
                if (ret)
                        goto free_iommu;

                iommu_set_root_entry(iommu);

                iommu->flush.flush_context(iommu, 0, 0, 0, DMA_CCMD_GLOBAL_INVL);
                iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
                iommu_enable_translation(iommu);
                iommu_disable_protect_mem_regions(iommu);
        }

        return 0;

free_iommu:
        for_each_active_iommu(iommu, drhd)
                free_dmar_iommu(iommu);
        kfree(deferred_flush);
free_g_iommus:
        kfree(g_iommus);
error:
        return ret;
}

/* This takes a number of _MM_ pages, not VTD pages */
static struct iova *intel_alloc_iova(struct device *dev,
                                     struct dmar_domain *domain,
                                     unsigned long nrpages, uint64_t dma_mask)
{
        struct iova *iova = NULL;

        /* Restrict dma_mask to the width that the iommu can handle */
        dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw), dma_mask);

        if (!dmar_forcedac && dma_mask > DMA_BIT_MASK(32)) {
                /*
                 * First try to allocate an io virtual address in
                 * DMA_BIT_MASK(32) and if that fails then try allocating
                 * from higher range
                 */
                iova = alloc_iova(&domain->iovad, nrpages,
                                  IOVA_PFN(DMA_BIT_MASK(32)), 1);
                if (iova)
                        return iova;
        }
        iova = alloc_iova(&domain->iovad, nrpages, IOVA_PFN(dma_mask), 1);
        if (unlikely(!iova)) {
                printk(KERN_ERR "Allocating %ld-page iova for %s failed",
                       nrpages, dev_name(dev));
                return NULL;
        }

        return iova;
}

static struct dmar_domain *__get_valid_domain_for_dev(struct device *dev)
{
        struct dmar_domain *domain;
        int ret;

        domain = get_domain_for_dev(dev, DEFAULT_DOMAIN_ADDRESS_WIDTH);
        if (!domain) {
                printk(KERN_ERR "Allocating domain for %s failed",
                       dev_name(dev));
                return NULL;
        }

        /* make sure context mapping is ok */
        if (unlikely(!domain_context_mapped(dev))) {
                ret = domain_context_mapping(domain, dev, CONTEXT_TT_MULTI_LEVEL);
                if (ret) {
                        printk(KERN_ERR "Domain context map for %s failed",
                               dev_name(dev));
                        return NULL;
                }
        }

        return domain;
}

static inline struct dmar_domain *get_valid_domain_for_dev(struct device *dev)
{
        struct device_domain_info *info;

        /* No lock here, assumes no domain exit in normal case */
        info = dev->archdata.iommu;
        if (likely(info))
                return info->domain;

        return __get_valid_domain_for_dev(dev);
}

static int iommu_dummy(struct device *dev)
{
        return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
}

/* Check if the dev needs to go through non-identity map and unmap process.*/
static int iommu_no_mapping(struct device *dev)
{
        int found;

        if (iommu_dummy(dev))
                return 1;

        if (!iommu_identity_mapping)
                return 0;

        found = identity_mapping(dev);
        if (found) {
                if (iommu_should_identity_map(dev, 0))
                        return 1;
                else {
                        /*
                         * 32 bit DMA is removed from si_domain and fall back
                         * to non-identity mapping.
                         */
                        domain_remove_one_dev_info(si_domain, dev);
                        printk(KERN_INFO "32bit %s uses non-identity mapping\n",
                               dev_name(dev));
                        return 0;
                }
        } else {
                /*
                 * In case of a detached 64 bit DMA device from vm, the device
                 * is put into si_domain for identity mapping.
                 */
                if (iommu_should_identity_map(dev, 0)) {
                        int ret;
                        ret = domain_add_dev_info(si_domain, dev,
                                                  hw_pass_through ?
                                                  CONTEXT_TT_PASS_THROUGH :
                                                  CONTEXT_TT_MULTI_LEVEL);
                        if (!ret) {
                                printk(KERN_INFO "64bit %s uses identity mapping\n",
                                       dev_name(dev));
                                return 1;
                        }
                }
        }

        return 0;
}

static dma_addr_t __intel_map_single(struct device *dev, phys_addr_t paddr,
                                     size_t size, int dir, u64 dma_mask)
{
        struct dmar_domain *domain;
        phys_addr_t start_paddr;
        struct iova *iova;
        int prot = 0;
        int ret;
        struct intel_iommu *iommu;
        unsigned long paddr_pfn = paddr >> PAGE_SHIFT;

        BUG_ON(dir == DMA_NONE);

        if (iommu_no_mapping(dev))
                return paddr;

        domain = get_valid_domain_for_dev(dev);
        if (!domain)
                return 0;

        iommu = domain_get_iommu(domain);
        size = aligned_nrpages(paddr, size);

        iova = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size), dma_mask);
        if (!iova)
                goto error;

        /*
         * Check if DMAR supports zero-length reads on write only
         * mappings..
         */
        if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL || \
                        !cap_zlr(iommu->cap))
                prot |= DMA_PTE_READ;
        if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
                prot |= DMA_PTE_WRITE;
        /*
         * paddr - (paddr + size) might be partial page, we should map the whole
         * page.  Note: if two part of one page are separately mapped, we
         * might have two guest_addr mapping to the same host paddr, but this
         * is not a big problem
         */
        ret = domain_pfn_mapping(domain, mm_to_dma_pfn(iova->pfn_lo),
                                 mm_to_dma_pfn(paddr_pfn), size, prot);
        if (ret)
                goto error;

        /* it's a non-present to present mapping. Only flush if caching mode */
        if (cap_caching_mode(iommu->cap))
                iommu_flush_iotlb_psi(iommu, domain->id, mm_to_dma_pfn(iova->pfn_lo), size, 0, 1);
        else
                iommu_flush_write_buffer(iommu);

        start_paddr = (phys_addr_t)iova->pfn_lo << PAGE_SHIFT;
        start_paddr += paddr & ~PAGE_MASK;
        return start_paddr;

error:
        if (iova)
                __free_iova(&domain->iovad, iova);
        printk(KERN_ERR"Device %s request: %zx@%llx dir %d --- failed\n",
                dev_name(dev), size, (unsigned long long)paddr, dir);
        return 0;
}

static dma_addr_t intel_map_page(struct device *dev, struct page *page,
                                 unsigned long offset, size_t size,
                                 enum dma_data_direction dir,
                                 struct dma_attrs *attrs)
{
        return __intel_map_single(dev, page_to_phys(page) + offset, size,
                                  dir, *dev->dma_mask);
}

static void flush_unmaps(void)
{
        int i, j;

        timer_on = 0;

        /* just flush them all */
        for (i = 0; i < g_num_of_iommus; i++) {
                struct intel_iommu *iommu = g_iommus[i];
                if (!iommu)
                        continue;

                if (!deferred_flush[i].next)
                        continue;

                /* In caching mode, global flushes turn emulation expensive */
                if (!cap_caching_mode(iommu->cap))
                        iommu->flush.flush_iotlb(iommu, 0, 0, 0,
                                         DMA_TLB_GLOBAL_FLUSH);
                for (j = 0; j < deferred_flush[i].next; j++) {
                        unsigned long mask;
                        struct iova *iova = deferred_flush[i].iova[j];
                        struct dmar_domain *domain = deferred_flush[i].domain[j];

                        /* On real hardware multiple invalidations are expensive */
                        if (cap_caching_mode(iommu->cap))
                                iommu_flush_iotlb_psi(iommu, domain->id,
                                        iova->pfn_lo, iova_size(iova),
                                        !deferred_flush[i].freelist[j], 0);
                        else {
                                mask = ilog2(mm_to_dma_pfn(iova_size(iova)));
                                iommu_flush_dev_iotlb(deferred_flush[i].domain[j],
                                                (uint64_t)iova->pfn_lo << PAGE_SHIFT, mask);
                        }
                        __free_iova(&deferred_flush[i].domain[j]->iovad, iova);
                        if (deferred_flush[i].freelist[j])
                                dma_free_pagelist(deferred_flush[i].freelist[j]);
                }
                deferred_flush[i].next = 0;
        }

        list_size = 0;
}

static void flush_unmaps_timeout(unsigned long data)
{
        unsigned long flags;

        spin_lock_irqsave(&async_umap_flush_lock, flags);
        flush_unmaps();
        spin_unlock_irqrestore(&async_umap_flush_lock, flags);
}

static void add_unmap(struct dmar_domain *dom, struct iova *iova, struct page *freelist)
{
        unsigned long flags;
        int next, iommu_id;
        struct intel_iommu *iommu;

        spin_lock_irqsave(&async_umap_flush_lock, flags);
        if (list_size == HIGH_WATER_MARK)
                flush_unmaps();

        iommu = domain_get_iommu(dom);
        iommu_id = iommu->seq_id;

        next = deferred_flush[iommu_id].next;
        deferred_flush[iommu_id].domain[next] = dom;
        deferred_flush[iommu_id].iova[next] = iova;
        deferred_flush[iommu_id].freelist[next] = freelist;
        deferred_flush[iommu_id].next++;

        if (!timer_on) {
                mod_timer(&unmap_timer, jiffies + msecs_to_jiffies(10));
                timer_on = 1;
        }
        list_size++;
        spin_unlock_irqrestore(&async_umap_flush_lock, flags);
}

static void intel_unmap(struct device *dev, dma_addr_t dev_addr)
{
        struct dmar_domain *domain;
        unsigned long start_pfn, last_pfn;
        struct iova *iova;
        struct intel_iommu *iommu;
        struct page *freelist;

        if (iommu_no_mapping(dev))
                return;

        domain = find_domain(dev);
        BUG_ON(!domain);

        iommu = domain_get_iommu(domain);

        iova = find_iova(&domain->iovad, IOVA_PFN(dev_addr));
        if (WARN_ONCE(!iova, "Driver unmaps unmatched page at PFN %llx\n",
                      (unsigned long long)dev_addr))
                return;

        start_pfn = mm_to_dma_pfn(iova->pfn_lo);
        last_pfn = mm_to_dma_pfn(iova->pfn_hi + 1) - 1;

        pr_debug("Device %s unmapping: pfn %lx-%lx\n",
                 dev_name(dev), start_pfn, last_pfn);

        freelist = domain_unmap(domain, start_pfn, last_pfn);

        if (intel_iommu_strict) {
                iommu_flush_iotlb_psi(iommu, domain->id, start_pfn,
                                      last_pfn - start_pfn + 1, !freelist, 0);
                /* free iova */
                __free_iova(&domain->iovad, iova);
                dma_free_pagelist(freelist);
        } else {
                add_unmap(domain, iova, freelist);
                /*
                 * queue up the release of the unmap to save the 1/6th of the
                 * cpu used up by the iotlb flush operation...
                 */
        }
}

static void intel_unmap_page(struct device *dev, dma_addr_t dev_addr,
                             size_t size, enum dma_data_direction dir,
                             struct dma_attrs *attrs)
{
        intel_unmap(dev, dev_addr);
}

static void *intel_alloc_coherent(struct device *dev, size_t size,
                                  dma_addr_t *dma_handle, gfp_t flags,
                                  struct dma_attrs *attrs)
{
        struct page *page = NULL;
        int order;

        size = PAGE_ALIGN(size);
        order = get_order(size);

        if (!iommu_no_mapping(dev))
                flags &= ~(GFP_DMA | GFP_DMA32);
        else if (dev->coherent_dma_mask < dma_get_required_mask(dev)) {
                if (dev->coherent_dma_mask < DMA_BIT_MASK(32))
                        flags |= GFP_DMA;
                else
                        flags |= GFP_DMA32;
        }

        if (flags & __GFP_WAIT) {
                unsigned int count = size >> PAGE_SHIFT;

                page = dma_alloc_from_contiguous(dev, count, order);
                if (page && iommu_no_mapping(dev) &&
                    page_to_phys(page) + size > dev->coherent_dma_mask) {
                        dma_release_from_contiguous(dev, page, count);
                        page = NULL;
                }
        }

        if (!page)
                page = alloc_pages(flags, order);
        if (!page)
                return NULL;
        memset(page_address(page), 0, size);

        *dma_handle = __intel_map_single(dev, page_to_phys(page), size,
                                         DMA_BIDIRECTIONAL,
                                         dev->coherent_dma_mask);
        if (*dma_handle)
                return page_address(page);
        if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
                __free_pages(page, order);

        return NULL;
}

static void intel_free_coherent(struct device *dev, size_t size, void *vaddr,
                                dma_addr_t dma_handle, struct dma_attrs *attrs)
{
        int order;
        struct page *page = virt_to_page(vaddr);

        size = PAGE_ALIGN(size);
        order = get_order(size);

        intel_unmap(dev, dma_handle);
        if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
                __free_pages(page, order);
}

static void intel_unmap_sg(struct device *dev, struct scatterlist *sglist,
                           int nelems, enum dma_data_direction dir,
                           struct dma_attrs *attrs)
{
        intel_unmap(dev, sglist[0].dma_address);
}

static int intel_nontranslate_map_sg(struct device *hddev,
        struct scatterlist *sglist, int nelems, int dir)
{
        int i;
        struct scatterlist *sg;

        for_each_sg(sglist, sg, nelems, i) {
                BUG_ON(!sg_page(sg));
                sg->dma_address = page_to_phys(sg_page(sg)) + sg->offset;
                sg->dma_length = sg->length;
        }
        return nelems;
}

static int intel_map_sg(struct device *dev, struct scatterlist *sglist, int nelems,
                        enum dma_data_direction dir, struct dma_attrs *attrs)
{
        int i;
        struct dmar_domain *domain;
        size_t size = 0;
        int prot = 0;
        struct iova *iova = NULL;
        int ret;
        struct scatterlist *sg;
        unsigned long start_vpfn;
        struct intel_iommu *iommu;

        BUG_ON(dir == DMA_NONE);
        if (iommu_no_mapping(dev))
                return intel_nontranslate_map_sg(dev, sglist, nelems, dir);

        domain = get_valid_domain_for_dev(dev);
        if (!domain)
                return 0;

        iommu = domain_get_iommu(domain);

        for_each_sg(sglist, sg, nelems, i)
                size += aligned_nrpages(sg->offset, sg->length);

        iova = intel_alloc_iova(dev, domain, dma_to_mm_pfn(size),
                                *dev->dma_mask);
        if (!iova) {
                sglist->dma_length = 0;
                return 0;
        }

        /*
         * Check if DMAR supports zero-length reads on write only
         * mappings..
         */
        if (dir == DMA_TO_DEVICE || dir == DMA_BIDIRECTIONAL || \
                        !cap_zlr(iommu->cap))
                prot |= DMA_PTE_READ;
        if (dir == DMA_FROM_DEVICE || dir == DMA_BIDIRECTIONAL)
                prot |= DMA_PTE_WRITE;

        start_vpfn = mm_to_dma_pfn(iova->pfn_lo);

        ret = domain_sg_mapping(domain, start_vpfn, sglist, size, prot);
        if (unlikely(ret)) {
                dma_pte_free_pagetable(domain, start_vpfn,
                                       start_vpfn + size - 1);
                __free_iova(&domain->iovad, iova);
                return 0;
        }

        /* it's a non-present to present mapping. Only flush if caching mode */
        if (cap_caching_mode(iommu->cap))
                iommu_flush_iotlb_psi(iommu, domain->id, start_vpfn, size, 0, 1);
        else
                iommu_flush_write_buffer(iommu);

        return nelems;
}

static int intel_mapping_error(struct device *dev, dma_addr_t dma_addr)
{
        return !dma_addr;
}

struct dma_map_ops intel_dma_ops = {
        .alloc = intel_alloc_coherent,
        .free = intel_free_coherent,
        .map_sg = intel_map_sg,
        .unmap_sg = intel_unmap_sg,
        .map_page = intel_map_page,
        .unmap_page = intel_unmap_page,
        .mapping_error = intel_mapping_error,
};

static inline int iommu_domain_cache_init(void)
{
        int ret = 0;

        iommu_domain_cache = kmem_cache_create("iommu_domain",
                                         sizeof(struct dmar_domain),
                                         0,
                                         SLAB_HWCACHE_ALIGN,

                                         NULL);
        if (!iommu_domain_cache) {
                printk(KERN_ERR "Couldn't create iommu_domain cache\n");
                ret = -ENOMEM;
        }

        return ret;
}

static inline int iommu_devinfo_cache_init(void)
{
        int ret = 0;

        iommu_devinfo_cache = kmem_cache_create("iommu_devinfo",
                                         sizeof(struct device_domain_info),
                                         0,
                                         SLAB_HWCACHE_ALIGN,
                                         NULL);
        if (!iommu_devinfo_cache) {
                printk(KERN_ERR "Couldn't create devinfo cache\n");
                ret = -ENOMEM;
        }

        return ret;
}

static inline int iommu_iova_cache_init(void)
{
        int ret = 0;

        iommu_iova_cache = kmem_cache_create("iommu_iova",
                                         sizeof(struct iova),
                                         0,
                                         SLAB_HWCACHE_ALIGN,
                                         NULL);
        if (!iommu_iova_cache) {
                printk(KERN_ERR "Couldn't create iova cache\n");
                ret = -ENOMEM;
        }

        return ret;
}

static int __init iommu_init_mempool(void)
{
        int ret;
        ret = iommu_iova_cache_init();
        if (ret)
                return ret;

        ret = iommu_domain_cache_init();
        if (ret)
                goto domain_error;

        ret = iommu_devinfo_cache_init();
        if (!ret)
                return ret;

        kmem_cache_destroy(iommu_domain_cache);
domain_error:
        kmem_cache_destroy(iommu_iova_cache);

        return -ENOMEM;
}

static void __init iommu_exit_mempool(void)
{
        kmem_cache_destroy(iommu_devinfo_cache);
        kmem_cache_destroy(iommu_domain_cache);
        kmem_cache_destroy(iommu_iova_cache);

}

static void quirk_ioat_snb_local_iommu(struct pci_dev *pdev)
{
        struct dmar_drhd_unit *drhd;
        u32 vtbar;
        int rc;

        /* We know that this device on this chipset has its own IOMMU.
         * If we find it under a different IOMMU, then the BIOS is lying
         * to us. Hope that the IOMMU for this device is actually
         * disabled, and it needs no translation...
         */
        rc = pci_bus_read_config_dword(pdev->bus, PCI_DEVFN(0, 0), 0xb0, &vtbar);
        if (rc) {
                /* "can't" happen */
                dev_info(&pdev->dev, "failed to run vt-d quirk\n");
                return;
        }
        vtbar &= 0xffff0000;

        /* we know that the this iommu should be at offset 0xa000 from vtbar */
        drhd = dmar_find_matched_drhd_unit(pdev);
        if (WARN_TAINT_ONCE(!drhd || drhd->reg_base_addr - vtbar != 0xa000,
                            TAINT_FIRMWARE_WORKAROUND,
                            "BIOS assigned incorrect VT-d unit for Intel(R) QuickData Technology device\n"))
                pdev->dev.archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
}
DECLARE_PCI_FIXUP_ENABLE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_IOAT_SNB, quirk_ioat_snb_local_iommu);

static void __init init_no_remapping_devices(void)
{
        struct dmar_drhd_unit *drhd;
        struct device *dev;
        int i;

        for_each_drhd_unit(drhd) {
                if (!drhd->include_all) {
                        for_each_active_dev_scope(drhd->devices,
                                                  drhd->devices_cnt, i, dev)
                                break;
                        /* ignore DMAR unit if no devices exist */
                        if (i == drhd->devices_cnt)
                                drhd->ignored = 1;
                }
        }

        for_each_active_drhd_unit(drhd) {
                if (drhd->include_all)
                        continue;

                for_each_active_dev_scope(drhd->devices,
                                          drhd->devices_cnt, i, dev)
                        if (!dev_is_pci(dev) || !IS_GFX_DEVICE(to_pci_dev(dev)))
                                break;
                if (i < drhd->devices_cnt)
                        continue;

                /* This IOMMU has *only* gfx devices. Either bypass it or
                   set the gfx_mapped flag, as appropriate */
                if (dmar_map_gfx) {
                        intel_iommu_gfx_mapped = 1;
                } else {
                        drhd->ignored = 1;
                        for_each_active_dev_scope(drhd->devices,
                                                  drhd->devices_cnt, i, dev)
                                dev->archdata.iommu = DUMMY_DEVICE_DOMAIN_INFO;
                }
        }
}

#ifdef CONFIG_SUSPEND
static int init_iommu_hw(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu = NULL;

        for_each_active_iommu(iommu, drhd)
                if (iommu->qi)
                        dmar_reenable_qi(iommu);

        for_each_iommu(iommu, drhd) {
                if (drhd->ignored) {
                        /*
                         * we always have to disable PMRs or DMA may fail on
                         * this device
                         */
                        if (force_on)
                                iommu_disable_protect_mem_regions(iommu);
                        continue;
                }
        
                iommu_flush_write_buffer(iommu);

                iommu_set_root_entry(iommu);

                iommu->flush.flush_context(iommu, 0, 0, 0,
                                           DMA_CCMD_GLOBAL_INVL);
                iommu->flush.flush_iotlb(iommu, 0, 0, 0, DMA_TLB_GLOBAL_FLUSH);
                iommu_enable_translation(iommu);
                iommu_disable_protect_mem_regions(iommu);
        }

        return 0;
}

static void iommu_flush_all(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;

        for_each_active_iommu(iommu, drhd) {
                iommu->flush.flush_context(iommu, 0, 0, 0,
                                           DMA_CCMD_GLOBAL_INVL);
                iommu->flush.flush_iotlb(iommu, 0, 0, 0,
                                         DMA_TLB_GLOBAL_FLUSH);
        }
}

static int iommu_suspend(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu = NULL;
        unsigned long flag;

        for_each_active_iommu(iommu, drhd) {
                iommu->iommu_state = kzalloc(sizeof(u32) * MAX_SR_DMAR_REGS,
                                                 GFP_ATOMIC);
                if (!iommu->iommu_state)
                        goto nomem;
        }

        iommu_flush_all();

        for_each_active_iommu(iommu, drhd) {
                iommu_disable_translation(iommu);

                raw_spin_lock_irqsave(&iommu->register_lock, flag);

                iommu->iommu_state[SR_DMAR_FECTL_REG] =
                        readl(iommu->reg + DMAR_FECTL_REG);
                iommu->iommu_state[SR_DMAR_FEDATA_REG] =
                        readl(iommu->reg + DMAR_FEDATA_REG);
                iommu->iommu_state[SR_DMAR_FEADDR_REG] =
                        readl(iommu->reg + DMAR_FEADDR_REG);
                iommu->iommu_state[SR_DMAR_FEUADDR_REG] =
                        readl(iommu->reg + DMAR_FEUADDR_REG);

                raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
        }
        return 0;

nomem:
        for_each_active_iommu(iommu, drhd)
                kfree(iommu->iommu_state);

        return -ENOMEM;
}

static void iommu_resume(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu = NULL;
        unsigned long flag;

        if (init_iommu_hw()) {
                if (force_on)
                        panic("tboot: IOMMU setup failed, DMAR can not resume!\n");
                else
                        WARN(1, "IOMMU setup failed, DMAR can not resume!\n");
                return;
        }

        for_each_active_iommu(iommu, drhd) {

                raw_spin_lock_irqsave(&iommu->register_lock, flag);

                writel(iommu->iommu_state[SR_DMAR_FECTL_REG],
                        iommu->reg + DMAR_FECTL_REG);
                writel(iommu->iommu_state[SR_DMAR_FEDATA_REG],
                        iommu->reg + DMAR_FEDATA_REG);
                writel(iommu->iommu_state[SR_DMAR_FEADDR_REG],
                        iommu->reg + DMAR_FEADDR_REG);
                writel(iommu->iommu_state[SR_DMAR_FEUADDR_REG],
                        iommu->reg + DMAR_FEUADDR_REG);

                raw_spin_unlock_irqrestore(&iommu->register_lock, flag);
        }

        for_each_active_iommu(iommu, drhd)
                kfree(iommu->iommu_state);
}

static struct syscore_ops iommu_syscore_ops = {
        .resume         = iommu_resume,
        .suspend        = iommu_suspend,
};

static void __init init_iommu_pm_ops(void)
{
        register_syscore_ops(&iommu_syscore_ops);
}

#else
static inline void init_iommu_pm_ops(void) {}
#endif  /* CONFIG_PM */


int __init dmar_parse_one_rmrr(struct acpi_dmar_header *header)
{
        struct acpi_dmar_reserved_memory *rmrr;
        struct dmar_rmrr_unit *rmrru;

        rmrru = kzalloc(sizeof(*rmrru), GFP_KERNEL);
        if (!rmrru)
                return -ENOMEM;

        rmrru->hdr = header;
        rmrr = (struct acpi_dmar_reserved_memory *)header;
        rmrru->base_address = rmrr->base_address;
        rmrru->end_address = rmrr->end_address;
        rmrru->devices = dmar_alloc_dev_scope((void *)(rmrr + 1),
                                ((void *)rmrr) + rmrr->header.length,
                                &rmrru->devices_cnt);
        if (rmrru->devices_cnt && rmrru->devices == NULL) {
                kfree(rmrru);
                return -ENOMEM;
        }

        list_add(&rmrru->list, &dmar_rmrr_units);

        return 0;
}

int __init dmar_parse_one_atsr(struct acpi_dmar_header *hdr)
{
        struct acpi_dmar_atsr *atsr;
        struct dmar_atsr_unit *atsru;

        atsr = container_of(hdr, struct acpi_dmar_atsr, header);
        atsru = kzalloc(sizeof(*atsru), GFP_KERNEL);
        if (!atsru)
                return -ENOMEM;

        atsru->hdr = hdr;
        atsru->include_all = atsr->flags & 0x1;
        if (!atsru->include_all) {
                atsru->devices = dmar_alloc_dev_scope((void *)(atsr + 1),
                                (void *)atsr + atsr->header.length,
                                &atsru->devices_cnt);
                if (atsru->devices_cnt && atsru->devices == NULL) {
                        kfree(atsru);
                        return -ENOMEM;
                }
        }

        list_add_rcu(&atsru->list, &dmar_atsr_units);

        return 0;
}

static void intel_iommu_free_atsr(struct dmar_atsr_unit *atsru)
{
        dmar_free_dev_scope(&atsru->devices, &atsru->devices_cnt);
        kfree(atsru);
}

static void intel_iommu_free_dmars(void)
{
        struct dmar_rmrr_unit *rmrru, *rmrr_n;
        struct dmar_atsr_unit *atsru, *atsr_n;

        list_for_each_entry_safe(rmrru, rmrr_n, &dmar_rmrr_units, list) {
                list_del(&rmrru->list);
                dmar_free_dev_scope(&rmrru->devices, &rmrru->devices_cnt);
                kfree(rmrru);
        }

        list_for_each_entry_safe(atsru, atsr_n, &dmar_atsr_units, list) {
                list_del(&atsru->list);
                intel_iommu_free_atsr(atsru);
        }
}

int dmar_find_matched_atsr_unit(struct pci_dev *dev)
{
        int i, ret = 1;
        struct pci_bus *bus;
        struct pci_dev *bridge = NULL;
        struct device *tmp;
        struct acpi_dmar_atsr *atsr;
        struct dmar_atsr_unit *atsru;

        dev = pci_physfn(dev);
        for (bus = dev->bus; bus; bus = bus->parent) {
                bridge = bus->self;
                if (!bridge || !pci_is_pcie(bridge) ||
                    pci_pcie_type(bridge) == PCI_EXP_TYPE_PCI_BRIDGE)
                        return 0;
                if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT)
                        break;
        }
        if (!bridge)
                return 0;

        rcu_read_lock();
        list_for_each_entry_rcu(atsru, &dmar_atsr_units, list) {
                atsr = container_of(atsru->hdr, struct acpi_dmar_atsr, header);
                if (atsr->segment != pci_domain_nr(dev->bus))
                        continue;

                for_each_dev_scope(atsru->devices, atsru->devices_cnt, i, tmp)
                        if (tmp == &bridge->dev)
                                goto out;

                if (atsru->include_all)
                        goto out;
        }
        ret = 0;
out:
        rcu_read_unlock();

        return ret;
}

int dmar_iommu_notify_scope_dev(struct dmar_pci_notify_info *info)
{
        int ret = 0;
        struct dmar_rmrr_unit *rmrru;
        struct dmar_atsr_unit *atsru;
        struct acpi_dmar_atsr *atsr;
        struct acpi_dmar_reserved_memory *rmrr;

        if (!intel_iommu_enabled && system_state != SYSTEM_BOOTING)
                return 0;

        list_for_each_entry(rmrru, &dmar_rmrr_units, list) {
                rmrr = container_of(rmrru->hdr,
                                    struct acpi_dmar_reserved_memory, header);
                if (info->event == BUS_NOTIFY_ADD_DEVICE) {
                        ret = dmar_insert_dev_scope(info, (void *)(rmrr + 1),
                                ((void *)rmrr) + rmrr->header.length,
                                rmrr->segment, rmrru->devices,
                                rmrru->devices_cnt);
                        if(ret < 0)
                                return ret;
                } else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
                        dmar_remove_dev_scope(info, rmrr->segment,
                                rmrru->devices, rmrru->devices_cnt);
                }
        }

        list_for_each_entry(atsru, &dmar_atsr_units, list) {
                if (atsru->include_all)
                        continue;

                atsr = container_of(atsru->hdr, struct acpi_dmar_atsr, header);
                if (info->event == BUS_NOTIFY_ADD_DEVICE) {
                        ret = dmar_insert_dev_scope(info, (void *)(atsr + 1),
                                        (void *)atsr + atsr->header.length,
                                        atsr->segment, atsru->devices,
                                        atsru->devices_cnt);
                        if (ret > 0)
                                break;
                        else if(ret < 0)
                                return ret;
                } else if (info->event == BUS_NOTIFY_DEL_DEVICE) {
                        if (dmar_remove_dev_scope(info, atsr->segment,
                                        atsru->devices, atsru->devices_cnt))
                                break;
                }
        }

        return 0;
}

/*
 * Here we only respond to action of unbound device from driver.
 *
 * Added device is not attached to its DMAR domain here yet. That will happen
 * when mapping the device to iova.
 */
static int device_notifier(struct notifier_block *nb,
                                  unsigned long action, void *data)
{
        struct device *dev = data;
        struct dmar_domain *domain;

        if (iommu_dummy(dev))
                return 0;

        if (action != BUS_NOTIFY_UNBOUND_DRIVER &&
            action != BUS_NOTIFY_DEL_DEVICE)
                return 0;

        /*
         * If the device is still attached to a device driver we can't
         * tear down the domain yet as DMA mappings may still be in use.
         * Wait for the BUS_NOTIFY_UNBOUND_DRIVER event to do that.
         */
        if (action == BUS_NOTIFY_DEL_DEVICE && dev->driver != NULL)
                return 0;

        domain = find_domain(dev);
        if (!domain)
                return 0;

        down_read(&dmar_global_lock);
        domain_remove_one_dev_info(domain, dev);
        if (!domain_type_is_vm_or_si(domain) && list_empty(&domain->devices))
                domain_exit(domain);
        up_read(&dmar_global_lock);

        return 0;
}

static struct notifier_block device_nb = {
        .notifier_call = device_notifier,
};

static int intel_iommu_memory_notifier(struct notifier_block *nb,
                                       unsigned long val, void *v)
{
        struct memory_notify *mhp = v;
        unsigned long long start, end;
        unsigned long start_vpfn, last_vpfn;

        switch (val) {
        case MEM_GOING_ONLINE:
                start = mhp->start_pfn << PAGE_SHIFT;
                end = ((mhp->start_pfn + mhp->nr_pages) << PAGE_SHIFT) - 1;
                if (iommu_domain_identity_map(si_domain, start, end)) {
                        pr_warn("dmar: failed to build identity map for [%llx-%llx]\n",
                                start, end);
                        return NOTIFY_BAD;
                }
                break;

        case MEM_OFFLINE:
        case MEM_CANCEL_ONLINE:
                start_vpfn = mm_to_dma_pfn(mhp->start_pfn);
                last_vpfn = mm_to_dma_pfn(mhp->start_pfn + mhp->nr_pages - 1);
                while (start_vpfn <= last_vpfn) {
                        struct iova *iova;
                        struct dmar_drhd_unit *drhd;
                        struct intel_iommu *iommu;
                        struct page *freelist;

                        iova = find_iova(&si_domain->iovad, start_vpfn);
                        if (iova == NULL) {
                                pr_debug("dmar: failed get IOVA for PFN %lx\n",
                                         start_vpfn);
                                break;
                        }

                        iova = split_and_remove_iova(&si_domain->iovad, iova,
                                                     start_vpfn, last_vpfn);
                        if (iova == NULL) {
                                pr_warn("dmar: failed to split IOVA PFN [%lx-%lx]\n",
                                        start_vpfn, last_vpfn);
                                return NOTIFY_BAD;
                        }

                        freelist = domain_unmap(si_domain, iova->pfn_lo,
                                               iova->pfn_hi);

                        rcu_read_lock();
                        for_each_active_iommu(iommu, drhd)
                                iommu_flush_iotlb_psi(iommu, si_domain->id,
                                        iova->pfn_lo, iova_size(iova),
                                        !freelist, 0);
                        rcu_read_unlock();
                        dma_free_pagelist(freelist);

                        start_vpfn = iova->pfn_hi + 1;
                        free_iova_mem(iova);
                }
                break;
        }

        return NOTIFY_OK;
}

static struct notifier_block intel_iommu_memory_nb = {
        .notifier_call = intel_iommu_memory_notifier,
        .priority = 0
};


static ssize_t intel_iommu_show_version(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct intel_iommu *iommu = dev_get_drvdata(dev);
        u32 ver = readl(iommu->reg + DMAR_VER_REG);
        return sprintf(buf, "%d:%d\n",
                       DMAR_VER_MAJOR(ver), DMAR_VER_MINOR(ver));
}
static DEVICE_ATTR(version, S_IRUGO, intel_iommu_show_version, NULL);

static ssize_t intel_iommu_show_address(struct device *dev,
                                        struct device_attribute *attr,
                                        char *buf)
{
        struct intel_iommu *iommu = dev_get_drvdata(dev);
        return sprintf(buf, "%llx\n", iommu->reg_phys);
}
static DEVICE_ATTR(address, S_IRUGO, intel_iommu_show_address, NULL);

static ssize_t intel_iommu_show_cap(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct intel_iommu *iommu = dev_get_drvdata(dev);
        return sprintf(buf, "%llx\n", iommu->cap);
}
static DEVICE_ATTR(cap, S_IRUGO, intel_iommu_show_cap, NULL);

static ssize_t intel_iommu_show_ecap(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct intel_iommu *iommu = dev_get_drvdata(dev);
        return sprintf(buf, "%llx\n", iommu->ecap);
}
static DEVICE_ATTR(ecap, S_IRUGO, intel_iommu_show_ecap, NULL);

static struct attribute *intel_iommu_attrs[] = {
        &dev_attr_version.attr,
        &dev_attr_address.attr,
        &dev_attr_cap.attr,
        &dev_attr_ecap.attr,
        NULL,
};

static struct attribute_group intel_iommu_group = {
        .name = "intel-iommu",
        .attrs = intel_iommu_attrs,
};

const struct attribute_group *intel_iommu_groups[] = {
        &intel_iommu_group,
        NULL,
};

int __init intel_iommu_init(void)
{
        int ret = -ENODEV;
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;

        /* VT-d is required for a TXT/tboot launch, so enforce that */
        force_on = tboot_force_iommu();

        if (iommu_init_mempool()) {
                if (force_on)
                        panic("tboot: Failed to initialize iommu memory\n");
                return -ENOMEM;
        }

        down_write(&dmar_global_lock);
        if (dmar_table_init()) {
                if (force_on)
                        panic("tboot: Failed to initialize DMAR table\n");
                goto out_free_dmar;
        }

        /*
         * Disable translation if already enabled prior to OS handover.
         */
        for_each_active_iommu(iommu, drhd)
                if (iommu->gcmd & DMA_GCMD_TE)
                        iommu_disable_translation(iommu);

        if (dmar_dev_scope_init() < 0) {
                if (force_on)
                        panic("tboot: Failed to initialize DMAR device scope\n");
                goto out_free_dmar;
        }

        if (no_iommu || dmar_disabled)
                goto out_free_dmar;

        if (list_empty(&dmar_rmrr_units))
                printk(KERN_INFO "DMAR: No RMRR found\n");

        if (list_empty(&dmar_atsr_units))
                printk(KERN_INFO "DMAR: No ATSR found\n");

        if (dmar_init_reserved_ranges()) {
                if (force_on)
                        panic("tboot: Failed to reserve iommu ranges\n");
                goto out_free_reserved_range;
        }

        init_no_remapping_devices();

        ret = init_dmars();
        if (ret) {
                if (force_on)
                        panic("tboot: Failed to initialize DMARs\n");
                printk(KERN_ERR "IOMMU: dmar init failed\n");
                goto out_free_reserved_range;
        }
        up_write(&dmar_global_lock);
        printk(KERN_INFO
        "PCI-DMA: Intel(R) Virtualization Technology for Directed I/O\n");

        init_timer(&unmap_timer);
#ifdef CONFIG_SWIOTLB
        swiotlb = 0;
#endif
        dma_ops = &intel_dma_ops;

        init_iommu_pm_ops();

        for_each_active_iommu(iommu, drhd)
                iommu->iommu_dev = iommu_device_create(NULL, iommu,
                                                       intel_iommu_groups,
                                                       iommu->name);

        bus_set_iommu(&pci_bus_type, &intel_iommu_ops);
        bus_register_notifier(&pci_bus_type, &device_nb);
        if (si_domain && !hw_pass_through)
                register_memory_notifier(&intel_iommu_memory_nb);

        intel_iommu_enabled = 1;

        return 0;

out_free_reserved_range:
        put_iova_domain(&reserved_iova_list);
out_free_dmar:
        intel_iommu_free_dmars();
        up_write(&dmar_global_lock);
        iommu_exit_mempool();
        return ret;
}

static int iommu_detach_dev_cb(struct pci_dev *pdev, u16 alias, void *opaque)
{
        struct intel_iommu *iommu = opaque;

        iommu_detach_dev(iommu, PCI_BUS_NUM(alias), alias & 0xff);
        return 0;
}

/*
 * NB - intel-iommu lacks any sort of reference counting for the users of
 * dependent devices.  If multiple endpoints have intersecting dependent
 * devices, unbinding the driver from any one of them will possibly leave
 * the others unable to operate.
 */
static void iommu_detach_dependent_devices(struct intel_iommu *iommu,
                                           struct device *dev)
{
        if (!iommu || !dev || !dev_is_pci(dev))
                return;

        pci_for_each_dma_alias(to_pci_dev(dev), &iommu_detach_dev_cb, iommu);
}

static void domain_remove_one_dev_info(struct dmar_domain *domain,
                                       struct device *dev)
{
        struct device_domain_info *info, *tmp;
        struct intel_iommu *iommu;
        unsigned long flags;
        int found = 0;
        u8 bus, devfn;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return;

        spin_lock_irqsave(&device_domain_lock, flags);
        list_for_each_entry_safe(info, tmp, &domain->devices, link) {
                if (info->iommu == iommu && info->bus == bus &&
                    info->devfn == devfn) {
                        unlink_domain_info(info);
                        spin_unlock_irqrestore(&device_domain_lock, flags);

                        iommu_disable_dev_iotlb(info);
                        iommu_detach_dev(iommu, info->bus, info->devfn);
                        iommu_detach_dependent_devices(iommu, dev);
                        free_devinfo_mem(info);

                        spin_lock_irqsave(&device_domain_lock, flags);

                        if (found)
                                break;
                        else
                                continue;
                }

                /* if there is no other devices under the same iommu
                 * owned by this domain, clear this iommu in iommu_bmp
                 * update iommu count and coherency
                 */
                if (info->iommu == iommu)
                        found = 1;
        }

        spin_unlock_irqrestore(&device_domain_lock, flags);

        if (found == 0) {
                domain_detach_iommu(domain, iommu);
                if (!domain_type_is_vm_or_si(domain))
                        iommu_detach_domain(domain, iommu);
        }
}

static int md_domain_init(struct dmar_domain *domain, int guest_width)
{
        int adjust_width;

        init_iova_domain(&domain->iovad, DMA_32BIT_PFN);
        domain_reserve_special_ranges(domain);

        /* calculate AGAW */
        domain->gaw = guest_width;
        adjust_width = guestwidth_to_adjustwidth(guest_width);
        domain->agaw = width_to_agaw(adjust_width);

        domain->iommu_coherency = 0;
        domain->iommu_snooping = 0;
        domain->iommu_superpage = 0;
        domain->max_addr = 0;

        /* always allocate the top pgd */
        domain->pgd = (struct dma_pte *)alloc_pgtable_page(domain->nid);
        if (!domain->pgd)
                return -ENOMEM;
        domain_flush_cache(domain, domain->pgd, PAGE_SIZE);
        return 0;
}

static int intel_iommu_domain_init(struct iommu_domain *domain)
{
        struct dmar_domain *dmar_domain;

        dmar_domain = alloc_domain(DOMAIN_FLAG_VIRTUAL_MACHINE);
        if (!dmar_domain) {
                printk(KERN_ERR
                        "intel_iommu_domain_init: dmar_domain == NULL\n");
                return -ENOMEM;
        }
        if (md_domain_init(dmar_domain, DEFAULT_DOMAIN_ADDRESS_WIDTH)) {
                printk(KERN_ERR
                        "intel_iommu_domain_init() failed\n");
                domain_exit(dmar_domain);
                return -ENOMEM;
        }
        domain_update_iommu_cap(dmar_domain);
        domain->priv = dmar_domain;

        domain->geometry.aperture_start = 0;
        domain->geometry.aperture_end   = __DOMAIN_MAX_ADDR(dmar_domain->gaw);
        domain->geometry.force_aperture = true;

        return 0;
}

static void intel_iommu_domain_destroy(struct iommu_domain *domain)
{
        struct dmar_domain *dmar_domain = domain->priv;

        domain->priv = NULL;
        domain_exit(dmar_domain);
}

static int intel_iommu_attach_device(struct iommu_domain *domain,
                                     struct device *dev)
{
        struct dmar_domain *dmar_domain = domain->priv;
        struct intel_iommu *iommu;
        int addr_width;
        u8 bus, devfn;

        if (device_is_rmrr_locked(dev)) {
                dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement.  Contact your platform vendor.\n");
                return -EPERM;
        }

        /* normally dev is not mapped */
        if (unlikely(domain_context_mapped(dev))) {
                struct dmar_domain *old_domain;

                old_domain = find_domain(dev);
                if (old_domain) {
                        if (domain_type_is_vm_or_si(dmar_domain))
                                domain_remove_one_dev_info(old_domain, dev);
                        else
                                domain_remove_dev_info(old_domain);
                }
        }

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return -ENODEV;

        /* check if this iommu agaw is sufficient for max mapped address */
        addr_width = agaw_to_width(iommu->agaw);
        if (addr_width > cap_mgaw(iommu->cap))
                addr_width = cap_mgaw(iommu->cap);

        if (dmar_domain->max_addr > (1LL << addr_width)) {
                printk(KERN_ERR "%s: iommu width (%d) is not "
                       "sufficient for the mapped address (%llx)\n",
                       __func__, addr_width, dmar_domain->max_addr);
                return -EFAULT;
        }
        dmar_domain->gaw = addr_width;

        /*
         * Knock out extra levels of page tables if necessary
         */
        while (iommu->agaw < dmar_domain->agaw) {
                struct dma_pte *pte;

                pte = dmar_domain->pgd;
                if (dma_pte_present(pte)) {
                        dmar_domain->pgd = (struct dma_pte *)
                                phys_to_virt(dma_pte_addr(pte));
                        free_pgtable_page(pte);
                }
                dmar_domain->agaw--;
        }

        return domain_add_dev_info(dmar_domain, dev, CONTEXT_TT_MULTI_LEVEL);
}

static void intel_iommu_detach_device(struct iommu_domain *domain,
                                      struct device *dev)
{
        struct dmar_domain *dmar_domain = domain->priv;

        domain_remove_one_dev_info(dmar_domain, dev);
}

static int intel_iommu_map(struct iommu_domain *domain,
                           unsigned long iova, phys_addr_t hpa,
                           size_t size, int iommu_prot)
{
        struct dmar_domain *dmar_domain = domain->priv;
        u64 max_addr;
        int prot = 0;
        int ret;

        if (iommu_prot & IOMMU_READ)
                prot |= DMA_PTE_READ;
        if (iommu_prot & IOMMU_WRITE)
                prot |= DMA_PTE_WRITE;
        if ((iommu_prot & IOMMU_CACHE) && dmar_domain->iommu_snooping)
                prot |= DMA_PTE_SNP;

        max_addr = iova + size;
        if (dmar_domain->max_addr < max_addr) {
                u64 end;

                /* check if minimum agaw is sufficient for mapped address */
                end = __DOMAIN_MAX_ADDR(dmar_domain->gaw) + 1;
                if (end < max_addr) {
                        printk(KERN_ERR "%s: iommu width (%d) is not "
                               "sufficient for the mapped address (%llx)\n",
                               __func__, dmar_domain->gaw, max_addr);
                        return -EFAULT;
                }
                dmar_domain->max_addr = max_addr;
        }
        /* Round up size to next multiple of PAGE_SIZE, if it and
           the low bits of hpa would take us onto the next page */
        size = aligned_nrpages(hpa, size);
        ret = domain_pfn_mapping(dmar_domain, iova >> VTD_PAGE_SHIFT,
                                 hpa >> VTD_PAGE_SHIFT, size, prot);
        return ret;
}

static size_t intel_iommu_unmap(struct iommu_domain *domain,
                                unsigned long iova, size_t size)
{
        struct dmar_domain *dmar_domain = domain->priv;
        struct page *freelist = NULL;
        struct intel_iommu *iommu;
        unsigned long start_pfn, last_pfn;
        unsigned int npages;
        int iommu_id, num, ndomains, level = 0;

        /* Cope with horrid API which requires us to unmap more than the
           size argument if it happens to be a large-page mapping. */
        if (!pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level))
                BUG();

        if (size < VTD_PAGE_SIZE << level_to_offset_bits(level))
                size = VTD_PAGE_SIZE << level_to_offset_bits(level);

        start_pfn = iova >> VTD_PAGE_SHIFT;
        last_pfn = (iova + size - 1) >> VTD_PAGE_SHIFT;

        freelist = domain_unmap(dmar_domain, start_pfn, last_pfn);

        npages = last_pfn - start_pfn + 1;

        for_each_set_bit(iommu_id, dmar_domain->iommu_bmp, g_num_of_iommus) {
               iommu = g_iommus[iommu_id];

               /*
                * find bit position of dmar_domain
                */
               ndomains = cap_ndoms(iommu->cap);
               for_each_set_bit(num, iommu->domain_ids, ndomains) {
                       if (iommu->domains[num] == dmar_domain)
                               iommu_flush_iotlb_psi(iommu, num, start_pfn,
                                                     npages, !freelist, 0);
               }

        }

        dma_free_pagelist(freelist);

        if (dmar_domain->max_addr == iova + size)
                dmar_domain->max_addr = iova;

        return size;
}

static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
                                            dma_addr_t iova)
{
        struct dmar_domain *dmar_domain = domain->priv;
        struct dma_pte *pte;
        int level = 0;
        u64 phys = 0;

        pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level);
        if (pte)
                phys = dma_pte_addr(pte);

        return phys;
}

static int intel_iommu_domain_has_cap(struct iommu_domain *domain,
                                      unsigned long cap)
{
        struct dmar_domain *dmar_domain = domain->priv;

        if (cap == IOMMU_CAP_CACHE_COHERENCY)
                return dmar_domain->iommu_snooping;
        if (cap == IOMMU_CAP_INTR_REMAP)
                return irq_remapping_enabled;

        return 0;
}

static int intel_iommu_add_device(struct device *dev)
{
        struct intel_iommu *iommu;
        struct iommu_group *group;
        u8 bus, devfn;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return -ENODEV;

        iommu_device_link(iommu->iommu_dev, dev);

        group = iommu_group_get_for_dev(dev);

        if (IS_ERR(group))
                return PTR_ERR(group);

        iommu_group_put(group);
        return 0;
}

static void intel_iommu_remove_device(struct device *dev)
{
        struct intel_iommu *iommu;
        u8 bus, devfn;

        iommu = device_to_iommu(dev, &bus, &devfn);
        if (!iommu)
                return;

        iommu_group_remove_device(dev);

        iommu_device_unlink(iommu->iommu_dev, dev);
}

static const struct iommu_ops intel_iommu_ops = {
        .domain_init    = intel_iommu_domain_init,
        .domain_destroy = intel_iommu_domain_destroy,
        .attach_dev     = intel_iommu_attach_device,
        .detach_dev     = intel_iommu_detach_device,
        .map            = intel_iommu_map,
        .unmap          = intel_iommu_unmap,
        .iova_to_phys   = intel_iommu_iova_to_phys,
        .domain_has_cap = intel_iommu_domain_has_cap,
        .add_device     = intel_iommu_add_device,
        .remove_device  = intel_iommu_remove_device,
        .pgsize_bitmap  = INTEL_IOMMU_PGSIZES,
};

static void quirk_iommu_g4x_gfx(struct pci_dev *dev)
{
        /* G4x/GM45 integrated gfx dmar support is totally busted. */
        printk(KERN_INFO "DMAR: Disabling IOMMU for graphics on this chipset\n");
        dmar_map_gfx = 0;
}

DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e00, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e10, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e20, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e30, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e40, quirk_iommu_g4x_gfx);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e90, quirk_iommu_g4x_gfx);

static void quirk_iommu_rwbf(struct pci_dev *dev)
{
        /*
         * Mobile 4 Series Chipset neglects to set RWBF capability,
         * but needs it. Same seems to hold for the desktop versions.
         */
        printk(KERN_INFO "DMAR: Forcing write-buffer flush capability\n");
        rwbf_quirk = 1;
}

DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e00, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e10, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e20, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e30, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e40, quirk_iommu_rwbf);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2e90, quirk_iommu_rwbf);

#define GGC 0x52
#define GGC_MEMORY_SIZE_MASK    (0xf << 8)
#define GGC_MEMORY_SIZE_NONE    (0x0 << 8)
#define GGC_MEMORY_SIZE_1M      (0x1 << 8)
#define GGC_MEMORY_SIZE_2M      (0x3 << 8)
#define GGC_MEMORY_VT_ENABLED   (0x8 << 8)
#define GGC_MEMORY_SIZE_2M_VT   (0x9 << 8)
#define GGC_MEMORY_SIZE_3M_VT   (0xa << 8)
#define GGC_MEMORY_SIZE_4M_VT   (0xb << 8)

static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
{
        unsigned short ggc;

        if (pci_read_config_word(dev, GGC, &ggc))
                return;

        if (!(ggc & GGC_MEMORY_VT_ENABLED)) {
                printk(KERN_INFO "DMAR: BIOS has allocated no shadow GTT; disabling IOMMU for graphics\n");
                dmar_map_gfx = 0;
        } else if (dmar_map_gfx) {
                /* we have to ensure the gfx device is idle before we flush */
                printk(KERN_INFO "DMAR: Disabling batched IOTLB flush on Ironlake\n");
                intel_iommu_strict = 1;
       }
}
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0040, quirk_calpella_no_shadow_gtt);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0044, quirk_calpella_no_shadow_gtt);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x0062, quirk_calpella_no_shadow_gtt);
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x006a, quirk_calpella_no_shadow_gtt);

/* On Tylersburg chipsets, some BIOSes have been known to enable the
   ISOCH DMAR unit for the Azalia sound device, but not give it any
   TLB entries, which causes it to deadlock. Check for that.  We do
   this in a function called from init_dmars(), instead of in a PCI
   quirk, because we don't want to print the obnoxious "BIOS broken"
   message if VT-d is actually disabled.
*/
static void __init check_tylersburg_isoch(void)
{
        struct pci_dev *pdev;
        uint32_t vtisochctrl;

        /* If there's no Azalia in the system anyway, forget it. */
        pdev = pci_get_device(PCI_VENDOR_ID_INTEL, 0x3a3e, NULL);
        if (!pdev)
                return;
        pci_dev_put(pdev);

        /* System Management Registers. Might be hidden, in which case
           we can't do the sanity check. But that's OK, because the
           known-broken BIOSes _don't_ actually hide it, so far. */
        pdev = pci_get_device(PCI_VENDOR_ID_INTEL, 0x342e, NULL);
        if (!pdev)
                return;

        if (pci_read_config_dword(pdev, 0x188, &vtisochctrl)) {
                pci_dev_put(pdev);
                return;
        }

        pci_dev_put(pdev);

        /* If Azalia DMA is routed to the non-isoch DMAR unit, fine. */
        if (vtisochctrl & 1)
                return;

        /* Drop all bits other than the number of TLB entries */
        vtisochctrl &= 0x1c;

        /* If we have the recommended number of TLB entries (16), fine. */
        if (vtisochctrl == 0x10)
                return;

        /* Zero TLB entries? You get to ride the short bus to school. */
        if (!vtisochctrl) {
                WARN(1, "Your BIOS is broken; DMA routed to ISOCH DMAR unit but no TLB space.\n"
                     "BIOS vendor: %s; Ver: %s; Product Version: %s\n",
                     dmi_get_system_info(DMI_BIOS_VENDOR),
                     dmi_get_system_info(DMI_BIOS_VERSION),
                     dmi_get_system_info(DMI_PRODUCT_VERSION));
                iommu_identity_mapping |= IDENTMAP_AZALIA;
                return;
        }
        
        printk(KERN_WARNING "DMAR: Recommended TLB entries for ISOCH unit is 16; your BIOS set %d\n",
               vtisochctrl);
}