diff options
| -rw-r--r-- | arch/x86/kvm/mmu.c | 57 |
1 files changed, 38 insertions, 19 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index a2fc65b..b160652 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -145,7 +145,8 @@ module_param(dbg, bool, 0644); #define CREATE_TRACE_POINTS #include "mmutrace.h" -#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) +#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) +#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1)) #define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level) @@ -1084,34 +1085,51 @@ static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) kvm_flush_remote_tlbs(vcpu->kvm); } +static bool spte_is_locklessly_modifiable(u64 spte) +{ + return !(~spte & (SPTE_HOST_WRITEABLE | SPTE_MMU_WRITEABLE)); +} + /* - * Write-protect on the specified @sptep due to dirty page logging or - * protecting shadow page table. @flush indicates whether tlb need be - * flushed. + * Write-protect on the specified @sptep, @pt_protect indicates whether + * spte writ-protection is caused by protecting shadow page table. + * @flush indicates whether tlb need be flushed. + * + * Note: write protection is difference between drity logging and spte + * protection: + * - for dirty logging, the spte can be set to writable at anytime if + * its dirty bitmap is properly set. + * - for spte protection, the spte can be writable only after unsync-ing + * shadow page. * * Return true if the spte is dropped. */ -static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush) +static bool +spte_write_protect(struct kvm *kvm, u64 *sptep, bool *flush, bool pt_protect) { u64 spte = *sptep; - if (!is_writable_pte(spte)) + if (!is_writable_pte(spte) && + !(pt_protect && spte_is_locklessly_modifiable(spte))) return false; rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, *sptep); - *flush |= true; - - if (__drop_large_spte(kvm, sptep)) + if (__drop_large_spte(kvm, sptep)) { + *flush |= true; return true; + } + if (pt_protect) + spte &= ~SPTE_MMU_WRITEABLE; spte = spte & ~PT_WRITABLE_MASK; - mmu_spte_update(sptep, spte); + + *flush |= mmu_spte_update(sptep, spte); return false; } -static bool -__rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level) +static bool __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, + int level, bool pt_protect) { u64 *sptep; struct rmap_iterator iter; @@ -1119,7 +1137,7 @@ __rmap_write_protect(struct kvm *kvm, unsigned long *rmapp, int level) for (sptep = rmap_get_first(*rmapp, &iter); sptep;) { BUG_ON(!(*sptep & PT_PRESENT_MASK)); - if (spte_write_protect(kvm, sptep, &flush)) { + if (spte_write_protect(kvm, sptep, &flush, pt_protect)) { sptep = rmap_get_first(*rmapp, &iter); continue; } @@ -1148,7 +1166,7 @@ void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, while (mask) { rmapp = &slot->rmap[gfn_offset + __ffs(mask)]; - __rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL); + __rmap_write_protect(kvm, rmapp, PT_PAGE_TABLE_LEVEL, false); /* clear the first set bit */ mask &= mask - 1; @@ -1167,7 +1185,7 @@ static bool rmap_write_protect(struct kvm *kvm, u64 gfn) for (i = PT_PAGE_TABLE_LEVEL; i < PT_PAGE_TABLE_LEVEL + KVM_NR_PAGE_SIZES; ++i) { rmapp = __gfn_to_rmap(gfn, i, slot); - write_protected |= __rmap_write_protect(kvm, rmapp, i); + write_protected |= __rmap_write_protect(kvm, rmapp, i, true); } return write_protected; @@ -2296,8 +2314,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, spte |= shadow_x_mask; else spte |= shadow_nx_mask; + if (pte_access & ACC_USER_MASK) spte |= shadow_user_mask; + if (level > PT_PAGE_TABLE_LEVEL) spte |= PT_PAGE_SIZE_MASK; if (tdp_enabled) @@ -2322,7 +2342,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, goto done; } - spte |= PT_WRITABLE_MASK; + spte |= PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE; if (!vcpu->arch.mmu.direct_map && !(pte_access & ACC_WRITE_MASK)) { @@ -2351,8 +2371,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, __func__, gfn); ret = 1; pte_access &= ~ACC_WRITE_MASK; - if (is_writable_pte(spte)) - spte &= ~PT_WRITABLE_MASK; + spte &= ~(PT_WRITABLE_MASK | SPTE_MMU_WRITEABLE); } } @@ -3933,7 +3952,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) !is_last_spte(pt[i], sp->role.level)) continue; - spte_write_protect(kvm, &pt[i], &flush); + spte_write_protect(kvm, &pt[i], &flush, false); } } kvm_flush_remote_tlbs(kvm); |