x86, AMD IOMMU: remove obsolete FIXME comment

[linux-2.6/zen-sources.git] / arch / x86 / kernel / amd_iommu.c

/*
 * Copyright (C) 2007-2008 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <joerg.roedel@amd.com>
 *         Leo Duran <leo.duran@amd.com>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 *
 * This program is distributed in the hope that 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/bitops.h>
#include <linux/scatterlist.h>
#include <linux/iommu-helper.h>
#include <asm/proto.h>
#include <asm/iommu.h>
#include <asm/amd_iommu_types.h>
#include <asm/amd_iommu.h>

#define CMD_SET_TYPE(cmd, t) ((cmd)->data[1] |= ((t) << 28))

#define EXIT_LOOP_COUNT 10000000

static DEFINE_RWLOCK(amd_iommu_devtable_lock);

/*
 * general struct to manage commands send to an IOMMU
 */
struct iommu_cmd {
        u32 data[4];
};

static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
                             struct unity_map_entry *e);

/* returns !0 if the IOMMU is caching non-present entries in its TLB */
static int iommu_has_npcache(struct amd_iommu *iommu)
{
        return iommu->cap & IOMMU_CAP_NPCACHE;
}

/****************************************************************************
 *
 * IOMMU command queuing functions
 *
 ****************************************************************************/

/*
 * Writes the command to the IOMMUs command buffer and informs the
 * hardware about the new command. Must be called with iommu->lock held.
 */
static int __iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
{
        u32 tail, head;
        u8 *target;

        tail = readl(iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);
        target = (iommu->cmd_buf + tail);
        memcpy_toio(target, cmd, sizeof(*cmd));
        tail = (tail + sizeof(*cmd)) % iommu->cmd_buf_size;
        head = readl(iommu->mmio_base + MMIO_CMD_HEAD_OFFSET);
        if (tail == head)
                return -ENOMEM;
        writel(tail, iommu->mmio_base + MMIO_CMD_TAIL_OFFSET);

        return 0;
}

/*
 * General queuing function for commands. Takes iommu->lock and calls
 * __iommu_queue_command().
 */
static int iommu_queue_command(struct amd_iommu *iommu, struct iommu_cmd *cmd)
{
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&iommu->lock, flags);
        ret = __iommu_queue_command(iommu, cmd);
        spin_unlock_irqrestore(&iommu->lock, flags);

        return ret;
}

/*
 * This function is called whenever we need to ensure that the IOMMU has
 * completed execution of all commands we sent. It sends a
 * COMPLETION_WAIT command and waits for it to finish. The IOMMU informs
 * us about that by writing a value to a physical address we pass with
 * the command.
 */
static int iommu_completion_wait(struct amd_iommu *iommu)
{
        int ret, ready = 0;
        unsigned status = 0;
        struct iommu_cmd cmd;
        unsigned long i = 0;

        memset(&cmd, 0, sizeof(cmd));
        cmd.data[0] = CMD_COMPL_WAIT_INT_MASK;
        CMD_SET_TYPE(&cmd, CMD_COMPL_WAIT);

        iommu->need_sync = 0;

        ret = iommu_queue_command(iommu, &cmd);

        if (ret)
                return ret;

        while (!ready && (i < EXIT_LOOP_COUNT)) {
                ++i;
                /* wait for the bit to become one */
                status = readl(iommu->mmio_base + MMIO_STATUS_OFFSET);
                ready = status & MMIO_STATUS_COM_WAIT_INT_MASK;
        }

        /* set bit back to zero */
        status &= ~MMIO_STATUS_COM_WAIT_INT_MASK;
        writel(status, iommu->mmio_base + MMIO_STATUS_OFFSET);

        if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit()))
                printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n");

        return 0;
}

/*
 * Command send function for invalidating a device table entry
 */
static int iommu_queue_inv_dev_entry(struct amd_iommu *iommu, u16 devid)
{
        struct iommu_cmd cmd;

        BUG_ON(iommu == NULL);

        memset(&cmd, 0, sizeof(cmd));
        CMD_SET_TYPE(&cmd, CMD_INV_DEV_ENTRY);
        cmd.data[0] = devid;

        iommu->need_sync = 1;

        return iommu_queue_command(iommu, &cmd);
}

/*
 * Generic command send function for invalidaing TLB entries
 */
static int iommu_queue_inv_iommu_pages(struct amd_iommu *iommu,
                u64 address, u16 domid, int pde, int s)
{
        struct iommu_cmd cmd;

        memset(&cmd, 0, sizeof(cmd));
        address &= PAGE_MASK;
        CMD_SET_TYPE(&cmd, CMD_INV_IOMMU_PAGES);
        cmd.data[1] |= domid;
        cmd.data[2] = lower_32_bits(address);
        cmd.data[3] = upper_32_bits(address);
        if (s) /* size bit - we flush more than one 4kb page */
                cmd.data[2] |= CMD_INV_IOMMU_PAGES_SIZE_MASK;
        if (pde) /* PDE bit - we wan't flush everything not only the PTEs */
                cmd.data[2] |= CMD_INV_IOMMU_PAGES_PDE_MASK;

        iommu->need_sync = 1;

        return iommu_queue_command(iommu, &cmd);
}

/*
 * TLB invalidation function which is called from the mapping functions.
 * It invalidates a single PTE if the range to flush is within a single
 * page. Otherwise it flushes the whole TLB of the IOMMU.
 */
static int iommu_flush_pages(struct amd_iommu *iommu, u16 domid,
                u64 address, size_t size)
{
        int s = 0;
        unsigned pages = iommu_num_pages(address, size);

        address &= PAGE_MASK;

        if (pages > 1) {
                /*
                 * If we have to flush more than one page, flush all
                 * TLB entries for this domain
                 */
                address = CMD_INV_IOMMU_ALL_PAGES_ADDRESS;
                s = 1;
        }

        iommu_queue_inv_iommu_pages(iommu, address, domid, 0, s);

        return 0;
}

/****************************************************************************
 *
 * The functions below are used the create the page table mappings for
 * unity mapped regions.
 *
 ****************************************************************************/

/*
 * Generic mapping functions. It maps a physical address into a DMA
 * address space. It allocates the page table pages if necessary.
 * In the future it can be extended to a generic mapping function
 * supporting all features of AMD IOMMU page tables like level skipping
 * and full 64 bit address spaces.
 */
static int iommu_map(struct protection_domain *dom,
                     unsigned long bus_addr,
                     unsigned long phys_addr,
                     int prot)
{
        u64 __pte, *pte, *page;

        bus_addr  = PAGE_ALIGN(bus_addr);
        phys_addr = PAGE_ALIGN(bus_addr);

        /* only support 512GB address spaces for now */
        if (bus_addr > IOMMU_MAP_SIZE_L3 || !(prot & IOMMU_PROT_MASK))
                return -EINVAL;

        pte = &dom->pt_root[IOMMU_PTE_L2_INDEX(bus_addr)];

        if (!IOMMU_PTE_PRESENT(*pte)) {
                page = (u64 *)get_zeroed_page(GFP_KERNEL);
                if (!page)
                        return -ENOMEM;
                *pte = IOMMU_L2_PDE(virt_to_phys(page));
        }

        pte = IOMMU_PTE_PAGE(*pte);
        pte = &pte[IOMMU_PTE_L1_INDEX(bus_addr)];

        if (!IOMMU_PTE_PRESENT(*pte)) {
                page = (u64 *)get_zeroed_page(GFP_KERNEL);
                if (!page)
                        return -ENOMEM;
                *pte = IOMMU_L1_PDE(virt_to_phys(page));
        }

        pte = IOMMU_PTE_PAGE(*pte);
        pte = &pte[IOMMU_PTE_L0_INDEX(bus_addr)];

        if (IOMMU_PTE_PRESENT(*pte))
                return -EBUSY;

        __pte = phys_addr | IOMMU_PTE_P;
        if (prot & IOMMU_PROT_IR)
                __pte |= IOMMU_PTE_IR;
        if (prot & IOMMU_PROT_IW)
                __pte |= IOMMU_PTE_IW;

        *pte = __pte;

        return 0;
}

/*
 * This function checks if a specific unity mapping entry is needed for
 * this specific IOMMU.
 */
static int iommu_for_unity_map(struct amd_iommu *iommu,
                               struct unity_map_entry *entry)
{
        u16 bdf, i;

        for (i = entry->devid_start; i <= entry->devid_end; ++i) {
                bdf = amd_iommu_alias_table[i];
                if (amd_iommu_rlookup_table[bdf] == iommu)
                        return 1;
        }

        return 0;
}

/*
 * Init the unity mappings for a specific IOMMU in the system
 *
 * Basically iterates over all unity mapping entries and applies them to
 * the default domain DMA of that IOMMU if necessary.
 */
static int iommu_init_unity_mappings(struct amd_iommu *iommu)
{
        struct unity_map_entry *entry;
        int ret;

        list_for_each_entry(entry, &amd_iommu_unity_map, list) {
                if (!iommu_for_unity_map(iommu, entry))
                        continue;
                ret = dma_ops_unity_map(iommu->default_dom, entry);
                if (ret)
                        return ret;
        }

        return 0;
}

/*
 * This function actually applies the mapping to the page table of the
 * dma_ops domain.
 */
static int dma_ops_unity_map(struct dma_ops_domain *dma_dom,
                             struct unity_map_entry *e)
{
        u64 addr;
        int ret;

        for (addr = e->address_start; addr < e->address_end;
             addr += PAGE_SIZE) {
                ret = iommu_map(&dma_dom->domain, addr, addr, e->prot);
                if (ret)
                        return ret;
                /*
                 * if unity mapping is in aperture range mark the page
                 * as allocated in the aperture
                 */
                if (addr < dma_dom->aperture_size)
                        __set_bit(addr >> PAGE_SHIFT, dma_dom->bitmap);
        }

        return 0;
}

/*
 * Inits the unity mappings required for a specific device
 */
static int init_unity_mappings_for_device(struct dma_ops_domain *dma_dom,
                                          u16 devid)
{
        struct unity_map_entry *e;
        int ret;

        list_for_each_entry(e, &amd_iommu_unity_map, list) {
                if (!(devid >= e->devid_start && devid <= e->devid_end))
                        continue;
                ret = dma_ops_unity_map(dma_dom, e);
                if (ret)
                        return ret;
        }

        return 0;
}

/****************************************************************************
 *
 * The next functions belong to the address allocator for the dma_ops
 * interface functions. They work like the allocators in the other IOMMU
 * drivers. Its basically a bitmap which marks the allocated pages in
 * the aperture. Maybe it could be enhanced in the future to a more
 * efficient allocator.
 *
 ****************************************************************************/
static unsigned long dma_mask_to_pages(unsigned long mask)
{
        return (mask >> PAGE_SHIFT) +
                (PAGE_ALIGN(mask & ~PAGE_MASK) >> PAGE_SHIFT);
}

/*
 * The address allocator core function.
 *
 * called with domain->lock held
 */
static unsigned long dma_ops_alloc_addresses(struct device *dev,
                                             struct dma_ops_domain *dom,
                                             unsigned int pages)
{
        unsigned long limit = dma_mask_to_pages(*dev->dma_mask);
        unsigned long address;
        unsigned long size = dom->aperture_size >> PAGE_SHIFT;
        unsigned long boundary_size;

        boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1,
                        PAGE_SIZE) >> PAGE_SHIFT;
        limit = limit < size ? limit : size;

        if (dom->next_bit >= limit)
                dom->next_bit = 0;

        address = iommu_area_alloc(dom->bitmap, limit, dom->next_bit, pages,
                        0 , boundary_size, 0);
        if (address == -1)
                address = iommu_area_alloc(dom->bitmap, limit, 0, pages,
                                0, boundary_size, 0);

        if (likely(address != -1)) {
                dom->next_bit = address + pages;
                address <<= PAGE_SHIFT;
        } else
                address = bad_dma_address;

        WARN_ON((address + (PAGE_SIZE*pages)) > dom->aperture_size);

        return address;
}

/*
 * The address free function.
 *
 * called with domain->lock held
 */
static void dma_ops_free_addresses(struct dma_ops_domain *dom,
                                   unsigned long address,
                                   unsigned int pages)
{
        address >>= PAGE_SHIFT;
        iommu_area_free(dom->bitmap, address, pages);
}

/****************************************************************************
 *
 * The next functions belong to the domain allocation. A domain is
 * allocated for every IOMMU as the default domain. If device isolation
 * is enabled, every device get its own domain. The most important thing
 * about domains is the page table mapping the DMA address space they
 * contain.
 *
 ****************************************************************************/

static u16 domain_id_alloc(void)
{
        unsigned long flags;
        int id;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        id = find_first_zero_bit(amd_iommu_pd_alloc_bitmap, MAX_DOMAIN_ID);
        BUG_ON(id == 0);
        if (id > 0 && id < MAX_DOMAIN_ID)
                __set_bit(id, amd_iommu_pd_alloc_bitmap);
        else
                id = 0;
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        return id;
}

/*
 * Used to reserve address ranges in the aperture (e.g. for exclusion
 * ranges.
 */
static void dma_ops_reserve_addresses(struct dma_ops_domain *dom,
                                      unsigned long start_page,
                                      unsigned int pages)
{
        unsigned int last_page = dom->aperture_size >> PAGE_SHIFT;

        if (start_page + pages > last_page)
                pages = last_page - start_page;

        set_bit_string(dom->bitmap, start_page, pages);
}

static void dma_ops_free_pagetable(struct dma_ops_domain *dma_dom)
{
        int i, j;
        u64 *p1, *p2, *p3;

        p1 = dma_dom->domain.pt_root;

        if (!p1)
                return;

        for (i = 0; i < 512; ++i) {
                if (!IOMMU_PTE_PRESENT(p1[i]))
                        continue;

                p2 = IOMMU_PTE_PAGE(p1[i]);
                for (j = 0; j < 512; ++i) {
                        if (!IOMMU_PTE_PRESENT(p2[j]))
                                continue;
                        p3 = IOMMU_PTE_PAGE(p2[j]);
                        free_page((unsigned long)p3);
                }

                free_page((unsigned long)p2);
        }

        free_page((unsigned long)p1);
}

/*
 * Free a domain, only used if something went wrong in the
 * allocation path and we need to free an already allocated page table
 */
static void dma_ops_domain_free(struct dma_ops_domain *dom)
{
        if (!dom)
                return;

        dma_ops_free_pagetable(dom);

        kfree(dom->pte_pages);

        kfree(dom->bitmap);

        kfree(dom);
}

/*
 * Allocates a new protection domain usable for the dma_ops functions.
 * It also intializes the page table and the address allocator data
 * structures required for the dma_ops interface
 */
static struct dma_ops_domain *dma_ops_domain_alloc(struct amd_iommu *iommu,
                                                   unsigned order)
{
        struct dma_ops_domain *dma_dom;
        unsigned i, num_pte_pages;
        u64 *l2_pde;
        u64 address;

        /*
         * Currently the DMA aperture must be between 32 MB and 1GB in size
         */
        if ((order < 25) || (order > 30))
                return NULL;

        dma_dom = kzalloc(sizeof(struct dma_ops_domain), GFP_KERNEL);
        if (!dma_dom)
                return NULL;

        spin_lock_init(&dma_dom->domain.lock);

        dma_dom->domain.id = domain_id_alloc();
        if (dma_dom->domain.id == 0)
                goto free_dma_dom;
        dma_dom->domain.mode = PAGE_MODE_3_LEVEL;
        dma_dom->domain.pt_root = (void *)get_zeroed_page(GFP_KERNEL);
        dma_dom->domain.priv = dma_dom;
        if (!dma_dom->domain.pt_root)
                goto free_dma_dom;
        dma_dom->aperture_size = (1ULL << order);
        dma_dom->bitmap = kzalloc(dma_dom->aperture_size / (PAGE_SIZE * 8),
                                  GFP_KERNEL);
        if (!dma_dom->bitmap)
                goto free_dma_dom;
        /*
         * mark the first page as allocated so we never return 0 as
         * a valid dma-address. So we can use 0 as error value
         */
        dma_dom->bitmap[0] = 1;
        dma_dom->next_bit = 0;

        /* Intialize the exclusion range if necessary */
        if (iommu->exclusion_start &&
            iommu->exclusion_start < dma_dom->aperture_size) {
                unsigned long startpage = iommu->exclusion_start >> PAGE_SHIFT;
                int pages = iommu_num_pages(iommu->exclusion_start,
                                            iommu->exclusion_length);
                dma_ops_reserve_addresses(dma_dom, startpage, pages);
        }

        /*
         * At the last step, build the page tables so we don't need to
         * allocate page table pages in the dma_ops mapping/unmapping
         * path.
         */
        num_pte_pages = dma_dom->aperture_size / (PAGE_SIZE * 512);
        dma_dom->pte_pages = kzalloc(num_pte_pages * sizeof(void *),
                        GFP_KERNEL);
        if (!dma_dom->pte_pages)
                goto free_dma_dom;

        l2_pde = (u64 *)get_zeroed_page(GFP_KERNEL);
        if (l2_pde == NULL)
                goto free_dma_dom;

        dma_dom->domain.pt_root[0] = IOMMU_L2_PDE(virt_to_phys(l2_pde));

        for (i = 0; i < num_pte_pages; ++i) {
                dma_dom->pte_pages[i] = (u64 *)get_zeroed_page(GFP_KERNEL);
                if (!dma_dom->pte_pages[i])
                        goto free_dma_dom;
                address = virt_to_phys(dma_dom->pte_pages[i]);
                l2_pde[i] = IOMMU_L1_PDE(address);
        }

        return dma_dom;

free_dma_dom:
        dma_ops_domain_free(dma_dom);

        return NULL;
}

/*
 * Find out the protection domain structure for a given PCI device. This
 * will give us the pointer to the page table root for example.
 */
static struct protection_domain *domain_for_device(u16 devid)
{
        struct protection_domain *dom;
        unsigned long flags;

        read_lock_irqsave(&amd_iommu_devtable_lock, flags);
        dom = amd_iommu_pd_table[devid];
        read_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        return dom;
}

/*
 * If a device is not yet associated with a domain, this function does
 * assigns it visible for the hardware
 */
static void set_device_domain(struct amd_iommu *iommu,
                              struct protection_domain *domain,
                              u16 devid)
{
        unsigned long flags;

        u64 pte_root = virt_to_phys(domain->pt_root);

        pte_root |= (domain->mode & 0x07) << 9;
        pte_root |= IOMMU_PTE_IR | IOMMU_PTE_IW | IOMMU_PTE_P | 2;

        write_lock_irqsave(&amd_iommu_devtable_lock, flags);
        amd_iommu_dev_table[devid].data[0] = pte_root;
        amd_iommu_dev_table[devid].data[1] = pte_root >> 32;
        amd_iommu_dev_table[devid].data[2] = domain->id;

        amd_iommu_pd_table[devid] = domain;
        write_unlock_irqrestore(&amd_iommu_devtable_lock, flags);

        iommu_queue_inv_dev_entry(iommu, devid);

        iommu->need_sync = 1;
}

/*****************************************************************************
 *
 * The next functions belong to the dma_ops mapping/unmapping code.
 *
 *****************************************************************************/

/*
 * In the dma_ops path we only have the struct device. This function
 * finds the corresponding IOMMU, the protection domain and the
 * requestor id for a given device.
 * If the device is not yet associated with a domain this is also done
 * in this function.
 */
static int get_device_resources(struct device *dev,
                                struct amd_iommu **iommu,
                                struct protection_domain **domain,
                                u16 *bdf)
{
        struct dma_ops_domain *dma_dom;
        struct pci_dev *pcidev;
        u16 _bdf;

        BUG_ON(!dev || dev->bus != &pci_bus_type || !dev->dma_mask);

        pcidev = to_pci_dev(dev);
        _bdf = calc_devid(pcidev->bus->number, pcidev->devfn);

        /* device not translated by any IOMMU in the system? */
        if (_bdf > amd_iommu_last_bdf) {
                *iommu = NULL;
                *domain = NULL;
                *bdf = 0xffff;
                return 0;
        }

        *bdf = amd_iommu_alias_table[_bdf];

        *iommu = amd_iommu_rlookup_table[*bdf];
        if (*iommu == NULL)
                return 0;
        dma_dom = (*iommu)->default_dom;
        *domain = domain_for_device(*bdf);
        if (*domain == NULL) {
                *domain = &dma_dom->domain;
                set_device_domain(*iommu, *domain, *bdf);
                printk(KERN_INFO "AMD IOMMU: Using protection domain %d for "
                                "device ", (*domain)->id);
                print_devid(_bdf, 1);
        }

        return 1;
}

/*
 * This is the generic map function. It maps one 4kb page at paddr to
 * the given address in the DMA address space for the domain.
 */
static dma_addr_t dma_ops_domain_map(struct amd_iommu *iommu,
                                     struct dma_ops_domain *dom,
                                     unsigned long address,
                                     phys_addr_t paddr,
                                     int direction)
{
        u64 *pte, __pte;

        WARN_ON(address > dom->aperture_size);

        paddr &= PAGE_MASK;

        pte  = dom->pte_pages[IOMMU_PTE_L1_INDEX(address)];
        pte += IOMMU_PTE_L0_INDEX(address);

        __pte = paddr | IOMMU_PTE_P | IOMMU_PTE_FC;

        if (direction == DMA_TO_DEVICE)
                __pte |= IOMMU_PTE_IR;
        else if (direction == DMA_FROM_DEVICE)
                __pte |= IOMMU_PTE_IW;
        else if (direction == DMA_BIDIRECTIONAL)
                __pte |= IOMMU_PTE_IR | IOMMU_PTE_IW;

        WARN_ON(*pte);

        *pte = __pte;

        return (dma_addr_t)address;
}

/*
 * The generic unmapping function for on page in the DMA address space.
 */
static void dma_ops_domain_unmap(struct amd_iommu *iommu,
                                 struct dma_ops_domain *dom,
                                 unsigned long address)
{
        u64 *pte;

        if (address >= dom->aperture_size)
                return;

        WARN_ON(address & 0xfffULL || address > dom->aperture_size);

        pte  = dom->pte_pages[IOMMU_PTE_L1_INDEX(address)];
        pte += IOMMU_PTE_L0_INDEX(address);

        WARN_ON(!*pte);

        *pte = 0ULL;
}

/*
 * This function contains common code for mapping of a physically
 * contiguous memory region into DMA address space. It is uses by all
 * mapping functions provided by this IOMMU driver.
 * Must be called with the domain lock held.
 */
static dma_addr_t __map_single(struct device *dev,
                               struct amd_iommu *iommu,
                               struct dma_ops_domain *dma_dom,
                               phys_addr_t paddr,
                               size_t size,
                               int dir)
{
        dma_addr_t offset = paddr & ~PAGE_MASK;
        dma_addr_t address, start;
        unsigned int pages;
        int i;

        pages = iommu_num_pages(paddr, size);
        paddr &= PAGE_MASK;

        address = dma_ops_alloc_addresses(dev, dma_dom, pages);
        if (unlikely(address == bad_dma_address))
                goto out;

        start = address;
        for (i = 0; i < pages; ++i) {
                dma_ops_domain_map(iommu, dma_dom, start, paddr, dir);
                paddr += PAGE_SIZE;
                start += PAGE_SIZE;
        }
        address += offset;

out:
        return address;
}

/*
 * Does the reverse of the __map_single function. Must be called with
 * the domain lock held too
 */
static void __unmap_single(struct amd_iommu *iommu,
                           struct dma_ops_domain *dma_dom,
                           dma_addr_t dma_addr,
                           size_t size,
                           int dir)
{
        dma_addr_t i, start;
        unsigned int pages;

        if ((dma_addr == 0) || (dma_addr + size > dma_dom->aperture_size))
                return;

        pages = iommu_num_pages(dma_addr, size);
        dma_addr &= PAGE_MASK;
        start = dma_addr;

        for (i = 0; i < pages; ++i) {
                dma_ops_domain_unmap(iommu, dma_dom, start);
                start += PAGE_SIZE;
        }

        dma_ops_free_addresses(dma_dom, dma_addr, pages);
}

/*
 * The exported map_single function for dma_ops.
 */
static dma_addr_t map_single(struct device *dev, phys_addr_t paddr,
                             size_t size, int dir)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        dma_addr_t addr;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (iommu == NULL || domain == NULL)
                /* device not handled by any AMD IOMMU */
                return (dma_addr_t)paddr;

        spin_lock_irqsave(&domain->lock, flags);
        addr = __map_single(dev, iommu, domain->priv, paddr, size, dir);
        if (addr == bad_dma_address)
                goto out;

        if (iommu_has_npcache(iommu))
                iommu_flush_pages(iommu, domain->id, addr, size);

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

out:
        spin_unlock_irqrestore(&domain->lock, flags);

        return addr;
}

/*
 * The exported unmap_single function for dma_ops.
 */
static void unmap_single(struct device *dev, dma_addr_t dma_addr,
                         size_t size, int dir)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;

        if (!get_device_resources(dev, &iommu, &domain, &devid))
                /* device not handled by any AMD IOMMU */
                return;

        spin_lock_irqsave(&domain->lock, flags);

        __unmap_single(iommu, domain->priv, dma_addr, size, dir);

        iommu_flush_pages(iommu, domain->id, dma_addr, size);

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);
}

/*
 * This is a special map_sg function which is used if we should map a
 * device which is not handled by an AMD IOMMU in the system.
 */
static int map_sg_no_iommu(struct device *dev, struct scatterlist *sglist,
                           int nelems, int dir)
{
        struct scatterlist *s;
        int i;

        for_each_sg(sglist, s, nelems, i) {
                s->dma_address = (dma_addr_t)sg_phys(s);
                s->dma_length  = s->length;
        }

        return nelems;
}

/*
 * The exported map_sg function for dma_ops (handles scatter-gather
 * lists).
 */
static int map_sg(struct device *dev, struct scatterlist *sglist,
                  int nelems, int dir)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        int i;
        struct scatterlist *s;
        phys_addr_t paddr;
        int mapped_elems = 0;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (!iommu || !domain)
                return map_sg_no_iommu(dev, sglist, nelems, dir);

        spin_lock_irqsave(&domain->lock, flags);

        for_each_sg(sglist, s, nelems, i) {
                paddr = sg_phys(s);

                s->dma_address = __map_single(dev, iommu, domain->priv,
                                              paddr, s->length, dir);

                if (s->dma_address) {
                        s->dma_length = s->length;
                        mapped_elems++;
                } else
                        goto unmap;
                if (iommu_has_npcache(iommu))
                        iommu_flush_pages(iommu, domain->id, s->dma_address,
                                          s->dma_length);
        }

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

out:
        spin_unlock_irqrestore(&domain->lock, flags);

        return mapped_elems;
unmap:
        for_each_sg(sglist, s, mapped_elems, i) {
                if (s->dma_address)
                        __unmap_single(iommu, domain->priv, s->dma_address,
                                       s->dma_length, dir);
                s->dma_address = s->dma_length = 0;
        }

        mapped_elems = 0;

        goto out;
}

/*
 * The exported map_sg function for dma_ops (handles scatter-gather
 * lists).
 */
static void unmap_sg(struct device *dev, struct scatterlist *sglist,
                     int nelems, int dir)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        struct scatterlist *s;
        u16 devid;
        int i;

        if (!get_device_resources(dev, &iommu, &domain, &devid))
                return;

        spin_lock_irqsave(&domain->lock, flags);

        for_each_sg(sglist, s, nelems, i) {
                __unmap_single(iommu, domain->priv, s->dma_address,
                               s->dma_length, dir);
                iommu_flush_pages(iommu, domain->id, s->dma_address,
                                  s->dma_length);
                s->dma_address = s->dma_length = 0;
        }

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);
}

/*
 * The exported alloc_coherent function for dma_ops.
 */
static void *alloc_coherent(struct device *dev, size_t size,
                            dma_addr_t *dma_addr, gfp_t flag)
{
        unsigned long flags;
        void *virt_addr;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;
        phys_addr_t paddr;

        virt_addr = (void *)__get_free_pages(flag, get_order(size));
        if (!virt_addr)
                return 0;

        memset(virt_addr, 0, size);
        paddr = virt_to_phys(virt_addr);

        get_device_resources(dev, &iommu, &domain, &devid);

        if (!iommu || !domain) {
                *dma_addr = (dma_addr_t)paddr;
                return virt_addr;
        }

        spin_lock_irqsave(&domain->lock, flags);

        *dma_addr = __map_single(dev, iommu, domain->priv, paddr,
                                 size, DMA_BIDIRECTIONAL);

        if (*dma_addr == bad_dma_address) {
                free_pages((unsigned long)virt_addr, get_order(size));
                virt_addr = NULL;
                goto out;
        }

        if (iommu_has_npcache(iommu))
                iommu_flush_pages(iommu, domain->id, *dma_addr, size);

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

out:
        spin_unlock_irqrestore(&domain->lock, flags);

        return virt_addr;
}

/*
 * The exported free_coherent function for dma_ops.
 */
static void free_coherent(struct device *dev, size_t size,
                          void *virt_addr, dma_addr_t dma_addr)
{
        unsigned long flags;
        struct amd_iommu *iommu;
        struct protection_domain *domain;
        u16 devid;

        get_device_resources(dev, &iommu, &domain, &devid);

        if (!iommu || !domain)
                goto free_mem;

        spin_lock_irqsave(&domain->lock, flags);

        __unmap_single(iommu, domain->priv, dma_addr, size, DMA_BIDIRECTIONAL);
        iommu_flush_pages(iommu, domain->id, dma_addr, size);

        if (iommu->need_sync)
                iommu_completion_wait(iommu);

        spin_unlock_irqrestore(&domain->lock, flags);

free_mem:
        free_pages((unsigned long)virt_addr, get_order(size));
}

/*
 * The function for pre-allocating protection domains.
 *
 * If the driver core informs the DMA layer if a driver grabs a device
 * we don't need to preallocate the protection domains anymore.
 * For now we have to.
 */
void prealloc_protection_domains(void)
{
        struct pci_dev *dev = NULL;
        struct dma_ops_domain *dma_dom;
        struct amd_iommu *iommu;
        int order = amd_iommu_aperture_order;
        u16 devid;

        while ((dev = pci_get_device(PCI_ANY_ID, PCI_ANY_ID, dev)) != NULL) {
                devid = (dev->bus->number << 8) | dev->devfn;
                if (devid > amd_iommu_last_bdf)
                        continue;
                devid = amd_iommu_alias_table[devid];
                if (domain_for_device(devid))
                        continue;
                iommu = amd_iommu_rlookup_table[devid];
                if (!iommu)
                        continue;
                dma_dom = dma_ops_domain_alloc(iommu, order);
                if (!dma_dom)
                        continue;
                init_unity_mappings_for_device(dma_dom, devid);
                set_device_domain(iommu, &dma_dom->domain, devid);
                printk(KERN_INFO "AMD IOMMU: Allocated domain %d for device ",
                       dma_dom->domain.id);
                print_devid(devid, 1);
        }
}

static struct dma_mapping_ops amd_iommu_dma_ops = {
        .alloc_coherent = alloc_coherent,
        .free_coherent = free_coherent,
        .map_single = map_single,
        .unmap_single = unmap_single,
        .map_sg = map_sg,
        .unmap_sg = unmap_sg,
};

/*
 * The function which clues the AMD IOMMU driver into dma_ops.
 */
int __init amd_iommu_init_dma_ops(void)
{
        struct amd_iommu *iommu;
        int order = amd_iommu_aperture_order;
        int ret;

        /*
         * first allocate a default protection domain for every IOMMU we
         * found in the system. Devices not assigned to any other
         * protection domain will be assigned to the default one.
         */
        list_for_each_entry(iommu, &amd_iommu_list, list) {
                iommu->default_dom = dma_ops_domain_alloc(iommu, order);
                if (iommu->default_dom == NULL)
                        return -ENOMEM;
                ret = iommu_init_unity_mappings(iommu);
                if (ret)
                        goto free_domains;
        }

        /*
         * If device isolation is enabled, pre-allocate the protection
         * domains for each device.
         */
        if (amd_iommu_isolate)
                prealloc_protection_domains();

        iommu_detected = 1;
        force_iommu = 1;
        bad_dma_address = 0;
#ifdef CONFIG_GART_IOMMU
        gart_iommu_aperture_disabled = 1;
        gart_iommu_aperture = 0;
#endif

        /* Make the driver finally visible to the drivers */
        dma_ops = &amd_iommu_dma_ops;

        return 0;

free_domains:

        list_for_each_entry(iommu, &amd_iommu_list, list) {
                if (iommu->default_dom)
                        dma_ops_domain_free(iommu->default_dom);
        }

        return ret;
}