nilfs2: fix oopses with doubly mounted snapshots

[linux-2.6/mini2440.git] / arch / powerpc / kvm / 44x_tlb.c

/*
 * 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, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright IBM Corp. 2007
 *
 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>

#include <asm/tlbflush.h>
#include <asm/mmu-44x.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_44x.h>
#include "timing.h"

#include "44x_tlb.h"

#ifndef PPC44x_TLBE_SIZE
#define PPC44x_TLBE_SIZE        PPC44x_TLB_4K
#endif

#define PAGE_SIZE_4K (1<<12)
#define PAGE_MASK_4K (~(PAGE_SIZE_4K - 1))

#define PPC44x_TLB_UATTR_MASK \
        (PPC44x_TLB_U0|PPC44x_TLB_U1|PPC44x_TLB_U2|PPC44x_TLB_U3)
#define PPC44x_TLB_USER_PERM_MASK (PPC44x_TLB_UX|PPC44x_TLB_UR|PPC44x_TLB_UW)
#define PPC44x_TLB_SUPER_PERM_MASK (PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW)

#ifdef DEBUG
void kvmppc_dump_tlbs(struct kvm_vcpu *vcpu)
{
        struct kvmppc_44x_tlbe *tlbe;
        int i;

        printk("vcpu %d TLB dump:\n", vcpu->vcpu_id);
        printk("| %2s | %3s | %8s | %8s | %8s |\n",
                        "nr", "tid", "word0", "word1", "word2");

        for (i = 0; i < ARRAY_SIZE(vcpu_44x->guest_tlb); i++) {
                tlbe = &vcpu_44x->guest_tlb[i];
                if (tlbe->word0 & PPC44x_TLB_VALID)
                        printk(" G%2d |  %02X | %08X | %08X | %08X |\n",
                               i, tlbe->tid, tlbe->word0, tlbe->word1,
                               tlbe->word2);
        }
}
#endif

static inline void kvmppc_44x_tlbie(unsigned int index)
{
        /* 0 <= index < 64, so the V bit is clear and we can use the index as
         * word0. */
        asm volatile(
                "tlbwe %[index], %[index], 0\n"
        :
        : [index] "r"(index)
        );
}

static inline void kvmppc_44x_tlbre(unsigned int index,
                                    struct kvmppc_44x_tlbe *tlbe)
{
        asm volatile(
                "tlbre %[word0], %[index], 0\n"
                "mfspr %[tid], %[sprn_mmucr]\n"
                "andi. %[tid], %[tid], 0xff\n"
                "tlbre %[word1], %[index], 1\n"
                "tlbre %[word2], %[index], 2\n"
                : [word0] "=r"(tlbe->word0),
                  [word1] "=r"(tlbe->word1),
                  [word2] "=r"(tlbe->word2),
                  [tid]   "=r"(tlbe->tid)
                : [index] "r"(index),
                  [sprn_mmucr] "i"(SPRN_MMUCR)
                : "cc"
        );
}

static inline void kvmppc_44x_tlbwe(unsigned int index,
                                    struct kvmppc_44x_tlbe *stlbe)
{
        unsigned long tmp;

        asm volatile(
                "mfspr %[tmp], %[sprn_mmucr]\n"
                "rlwimi %[tmp], %[tid], 0, 0xff\n"
                "mtspr %[sprn_mmucr], %[tmp]\n"
                "tlbwe %[word0], %[index], 0\n"
                "tlbwe %[word1], %[index], 1\n"
                "tlbwe %[word2], %[index], 2\n"
                : [tmp]   "=&r"(tmp)
                : [word0] "r"(stlbe->word0),
                  [word1] "r"(stlbe->word1),
                  [word2] "r"(stlbe->word2),
                  [tid]   "r"(stlbe->tid),
                  [index] "r"(index),
                  [sprn_mmucr] "i"(SPRN_MMUCR)
        );
}

static u32 kvmppc_44x_tlb_shadow_attrib(u32 attrib, int usermode)
{
        /* We only care about the guest's permission and user bits. */
        attrib &= PPC44x_TLB_PERM_MASK|PPC44x_TLB_UATTR_MASK;

        if (!usermode) {
                /* Guest is in supervisor mode, so we need to translate guest
                 * supervisor permissions into user permissions. */
                attrib &= ~PPC44x_TLB_USER_PERM_MASK;
                attrib |= (attrib & PPC44x_TLB_SUPER_PERM_MASK) << 3;
        }

        /* Make sure host can always access this memory. */
        attrib |= PPC44x_TLB_SX|PPC44x_TLB_SR|PPC44x_TLB_SW;

        /* WIMGE = 0b00100 */
        attrib |= PPC44x_TLB_M;

        return attrib;
}

/* Load shadow TLB back into hardware. */
void kvmppc_44x_tlb_load(struct kvm_vcpu *vcpu)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        for (i = 0; i <= tlb_44x_hwater; i++) {
                struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];

                if (get_tlb_v(stlbe) && get_tlb_ts(stlbe))
                        kvmppc_44x_tlbwe(i, stlbe);
        }
}

static void kvmppc_44x_tlbe_set_modified(struct kvmppc_vcpu_44x *vcpu_44x,
                                         unsigned int i)
{
        vcpu_44x->shadow_tlb_mod[i] = 1;
}

/* Save hardware TLB to the vcpu, and invalidate all guest mappings. */
void kvmppc_44x_tlb_put(struct kvm_vcpu *vcpu)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        for (i = 0; i <= tlb_44x_hwater; i++) {
                struct kvmppc_44x_tlbe *stlbe = &vcpu_44x->shadow_tlb[i];

                if (vcpu_44x->shadow_tlb_mod[i])
                        kvmppc_44x_tlbre(i, stlbe);

                if (get_tlb_v(stlbe) && get_tlb_ts(stlbe))
                        kvmppc_44x_tlbie(i);
        }
}


/* Search the guest TLB for a matching entry. */
int kvmppc_44x_tlb_index(struct kvm_vcpu *vcpu, gva_t eaddr, unsigned int pid,
                         unsigned int as)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        /* XXX Replace loop with fancy data structures. */
        for (i = 0; i < ARRAY_SIZE(vcpu_44x->guest_tlb); i++) {
                struct kvmppc_44x_tlbe *tlbe = &vcpu_44x->guest_tlb[i];
                unsigned int tid;

                if (eaddr < get_tlb_eaddr(tlbe))
                        continue;

                if (eaddr > get_tlb_end(tlbe))
                        continue;

                tid = get_tlb_tid(tlbe);
                if (tid && (tid != pid))
                        continue;

                if (!get_tlb_v(tlbe))
                        continue;

                if (get_tlb_ts(tlbe) != as)
                        continue;

                return i;
        }

        return -1;
}

gpa_t kvmppc_mmu_xlate(struct kvm_vcpu *vcpu, unsigned int gtlb_index,
                       gva_t eaddr)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        struct kvmppc_44x_tlbe *gtlbe = &vcpu_44x->guest_tlb[gtlb_index];
        unsigned int pgmask = get_tlb_bytes(gtlbe) - 1;

        return get_tlb_raddr(gtlbe) | (eaddr & pgmask);
}

int kvmppc_mmu_itlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
{
        unsigned int as = !!(vcpu->arch.msr & MSR_IS);

        return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
}

int kvmppc_mmu_dtlb_index(struct kvm_vcpu *vcpu, gva_t eaddr)
{
        unsigned int as = !!(vcpu->arch.msr & MSR_DS);

        return kvmppc_44x_tlb_index(vcpu, eaddr, vcpu->arch.pid, as);
}

void kvmppc_mmu_itlb_miss(struct kvm_vcpu *vcpu)
{
}

void kvmppc_mmu_dtlb_miss(struct kvm_vcpu *vcpu)
{
}

static void kvmppc_44x_shadow_release(struct kvmppc_vcpu_44x *vcpu_44x,
                                      unsigned int stlb_index)
{
        struct kvmppc_44x_shadow_ref *ref = &vcpu_44x->shadow_refs[stlb_index];

        if (!ref->page)
                return;

        /* Discard from the TLB. */
        /* Note: we could actually invalidate a host mapping, if the host overwrote
         * this TLB entry since we inserted a guest mapping. */
        kvmppc_44x_tlbie(stlb_index);

        /* Now release the page. */
        if (ref->writeable)
                kvm_release_page_dirty(ref->page);
        else
                kvm_release_page_clean(ref->page);

        ref->page = NULL;

        /* XXX set tlb_44x_index to stlb_index? */

        KVMTRACE_1D(STLB_INVAL, &vcpu_44x->vcpu, stlb_index, handler);
}

void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        for (i = 0; i <= tlb_44x_hwater; i++)
                kvmppc_44x_shadow_release(vcpu_44x, i);
}

/**
 * kvmppc_mmu_map -- create a host mapping for guest memory
 *
 * If the guest wanted a larger page than the host supports, only the first
 * host page is mapped here and the rest are demand faulted.
 *
 * If the guest wanted a smaller page than the host page size, we map only the
 * guest-size page (i.e. not a full host page mapping).
 *
 * Caller must ensure that the specified guest TLB entry is safe to insert into
 * the shadow TLB.
 */
void kvmppc_mmu_map(struct kvm_vcpu *vcpu, u64 gvaddr, gpa_t gpaddr,
                    unsigned int gtlb_index)
{
        struct kvmppc_44x_tlbe stlbe;
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        struct kvmppc_44x_tlbe *gtlbe = &vcpu_44x->guest_tlb[gtlb_index];
        struct kvmppc_44x_shadow_ref *ref;
        struct page *new_page;
        hpa_t hpaddr;
        gfn_t gfn;
        u32 asid = gtlbe->tid;
        u32 flags = gtlbe->word2;
        u32 max_bytes = get_tlb_bytes(gtlbe);
        unsigned int victim;

        /* Select TLB entry to clobber. Indirectly guard against races with the TLB
         * miss handler by disabling interrupts. */
        local_irq_disable();
        victim = ++tlb_44x_index;
        if (victim > tlb_44x_hwater)
                victim = 0;
        tlb_44x_index = victim;
        local_irq_enable();

        /* Get reference to new page. */
        gfn = gpaddr >> PAGE_SHIFT;
        new_page = gfn_to_page(vcpu->kvm, gfn);
        if (is_error_page(new_page)) {
                printk(KERN_ERR "Couldn't get guest page for gfn %lx!\n", gfn);
                kvm_release_page_clean(new_page);
                return;
        }
        hpaddr = page_to_phys(new_page);

        /* Invalidate any previous shadow mappings. */
        kvmppc_44x_shadow_release(vcpu_44x, victim);

        /* XXX Make sure (va, size) doesn't overlap any other
         * entries. 440x6 user manual says the result would be
         * "undefined." */

        /* XXX what about AS? */

        /* Force TS=1 for all guest mappings. */
        stlbe.word0 = PPC44x_TLB_VALID | PPC44x_TLB_TS;

        if (max_bytes >= PAGE_SIZE) {
                /* Guest mapping is larger than or equal to host page size. We can use
                 * a "native" host mapping. */
                stlbe.word0 |= (gvaddr & PAGE_MASK) | PPC44x_TLBE_SIZE;
        } else {
                /* Guest mapping is smaller than host page size. We must restrict the
                 * size of the mapping to be at most the smaller of the two, but for
                 * simplicity we fall back to a 4K mapping (this is probably what the
                 * guest is using anyways). */
                stlbe.word0 |= (gvaddr & PAGE_MASK_4K) | PPC44x_TLB_4K;

                /* 'hpaddr' is a host page, which is larger than the mapping we're
                 * inserting here. To compensate, we must add the in-page offset to the
                 * sub-page. */
                hpaddr |= gpaddr & (PAGE_MASK ^ PAGE_MASK_4K);
        }

        stlbe.word1 = (hpaddr & 0xfffffc00) | ((hpaddr >> 32) & 0xf);
        stlbe.word2 = kvmppc_44x_tlb_shadow_attrib(flags,
                                                    vcpu->arch.msr & MSR_PR);
        stlbe.tid = !(asid & 0xff);

        /* Keep track of the reference so we can properly release it later. */
        ref = &vcpu_44x->shadow_refs[victim];
        ref->page = new_page;
        ref->gtlb_index = gtlb_index;
        ref->writeable = !!(stlbe.word2 & PPC44x_TLB_UW);
        ref->tid = stlbe.tid;

        /* Insert shadow mapping into hardware TLB. */
        kvmppc_44x_tlbe_set_modified(vcpu_44x, victim);
        kvmppc_44x_tlbwe(victim, &stlbe);
        KVMTRACE_5D(STLB_WRITE, vcpu, victim, stlbe.tid, stlbe.word0, stlbe.word1,
                    stlbe.word2, handler);
}

/* For a particular guest TLB entry, invalidate the corresponding host TLB
 * mappings and release the host pages. */
static void kvmppc_44x_invalidate(struct kvm_vcpu *vcpu,
                                  unsigned int gtlb_index)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        for (i = 0; i < ARRAY_SIZE(vcpu_44x->shadow_refs); i++) {
                struct kvmppc_44x_shadow_ref *ref = &vcpu_44x->shadow_refs[i];
                if (ref->gtlb_index == gtlb_index)
                        kvmppc_44x_shadow_release(vcpu_44x, i);
        }
}

void kvmppc_mmu_priv_switch(struct kvm_vcpu *vcpu, int usermode)
{
        vcpu->arch.shadow_pid = !usermode;
}

void kvmppc_set_pid(struct kvm_vcpu *vcpu, u32 new_pid)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        int i;

        if (unlikely(vcpu->arch.pid == new_pid))
                return;

        vcpu->arch.pid = new_pid;

        /* Guest userspace runs with TID=0 mappings and PID=0, to make sure it
         * can't access guest kernel mappings (TID=1). When we switch to a new
         * guest PID, which will also use host PID=0, we must discard the old guest
         * userspace mappings. */
        for (i = 0; i < ARRAY_SIZE(vcpu_44x->shadow_refs); i++) {
                struct kvmppc_44x_shadow_ref *ref = &vcpu_44x->shadow_refs[i];

                if (ref->tid == 0)
                        kvmppc_44x_shadow_release(vcpu_44x, i);
        }
}

static int tlbe_is_host_safe(const struct kvm_vcpu *vcpu,
                             const struct kvmppc_44x_tlbe *tlbe)
{
        gpa_t gpa;

        if (!get_tlb_v(tlbe))
                return 0;

        /* Does it match current guest AS? */
        /* XXX what about IS != DS? */
        if (get_tlb_ts(tlbe) != !!(vcpu->arch.msr & MSR_IS))
                return 0;

        gpa = get_tlb_raddr(tlbe);
        if (!gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT))
                /* Mapping is not for RAM. */
                return 0;

        return 1;
}

int kvmppc_44x_emul_tlbwe(struct kvm_vcpu *vcpu, u8 ra, u8 rs, u8 ws)
{
        struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
        struct kvmppc_44x_tlbe *tlbe;
        unsigned int gtlb_index;

        gtlb_index = vcpu->arch.gpr[ra];
        if (gtlb_index > KVM44x_GUEST_TLB_SIZE) {
                printk("%s: index %d\n", __func__, gtlb_index);
                kvmppc_dump_vcpu(vcpu);
                return EMULATE_FAIL;
        }

        tlbe = &vcpu_44x->guest_tlb[gtlb_index];

        /* Invalidate shadow mappings for the about-to-be-clobbered TLB entry. */
        if (tlbe->word0 & PPC44x_TLB_VALID)
                kvmppc_44x_invalidate(vcpu, gtlb_index);

        switch (ws) {
        case PPC44x_TLB_PAGEID:
                tlbe->tid = get_mmucr_stid(vcpu);
                tlbe->word0 = vcpu->arch.gpr[rs];
                break;

        case PPC44x_TLB_XLAT:
                tlbe->word1 = vcpu->arch.gpr[rs];
                break;

        case PPC44x_TLB_ATTRIB:
                tlbe->word2 = vcpu->arch.gpr[rs];
                break;

        default:
                return EMULATE_FAIL;
        }

        if (tlbe_is_host_safe(vcpu, tlbe)) {
                gva_t eaddr;
                gpa_t gpaddr;
                u32 bytes;

                eaddr = get_tlb_eaddr(tlbe);
                gpaddr = get_tlb_raddr(tlbe);

                /* Use the advertised page size to mask effective and real addrs. */
                bytes = get_tlb_bytes(tlbe);
                eaddr &= ~(bytes - 1);
                gpaddr &= ~(bytes - 1);

                kvmppc_mmu_map(vcpu, eaddr, gpaddr, gtlb_index);
        }

        KVMTRACE_5D(GTLB_WRITE, vcpu, gtlb_index, tlbe->tid, tlbe->word0,
                    tlbe->word1, tlbe->word2, handler);

        kvmppc_set_exit_type(vcpu, EMULATED_TLBWE_EXITS);
        return EMULATE_DONE;
}

int kvmppc_44x_emul_tlbsx(struct kvm_vcpu *vcpu, u8 rt, u8 ra, u8 rb, u8 rc)
{
        u32 ea;
        int gtlb_index;
        unsigned int as = get_mmucr_sts(vcpu);
        unsigned int pid = get_mmucr_stid(vcpu);

        ea = vcpu->arch.gpr[rb];
        if (ra)
                ea += vcpu->arch.gpr[ra];

        gtlb_index = kvmppc_44x_tlb_index(vcpu, ea, pid, as);
        if (rc) {
                if (gtlb_index < 0)
                        vcpu->arch.cr &= ~0x20000000;
                else
                        vcpu->arch.cr |= 0x20000000;
        }
        vcpu->arch.gpr[rt] = gtlb_index;

        kvmppc_set_exit_type(vcpu, EMULATED_TLBSX_EXITS);
        return EMULATE_DONE;
}