Messages in this thread Patch in this message | | | Date | Fri, 20 Apr 2012 16:19:17 +0800 | From | Xiao Guangrong <> | Subject | [PATCH v3 5/9] KVM: MMU: introduce SPTE_WRITE_PROTECT bit |
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If this bit is set, it means the W bit of the spte is cleared due to shadow page table protection
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> --- arch/x86/kvm/mmu.c | 56 ++++++++++++++++++++++++++++++++++----------------- 1 files changed, 37 insertions(+), 19 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index dd984b6..eb02fc4 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -147,6 +147,7 @@ module_param(dbg, bool, 0644);
#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT) #define SPTE_ALLOW_WRITE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1)) +#define SPTE_WRITE_PROTECT (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 2))
#define SHADOW_PT_INDEX(addr, level) PT64_INDEX(addr, level)
@@ -1042,36 +1043,51 @@ static void drop_spte(struct kvm *kvm, u64 *sptep) rmap_remove(kvm, sptep); }
+static bool spte_wp_by_dirty_log(u64 spte) +{ + WARN_ON(is_writable_pte(spte)); + + return (spte & SPTE_ALLOW_WRITE) && !(spte & SPTE_WRITE_PROTECT); +} + /* Return true if the spte is dropped. */ static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool large, - bool *flush) + bool *flush, bool page_table_protect) { u64 spte = *sptep;
- if (!is_writable_pte(spte)) - return false; + if (is_writable_pte(spte)) { + *flush |= true;
- *flush |= true; + if (large) { + pgprintk("rmap_write_protect(large): spte %p %llx\n", + spte, *spte); + BUG_ON(!is_large_pte(spte));
- if (large) { - pgprintk("rmap_write_protect(large): spte %p %llx\n", - spte, *spte); - BUG_ON(!is_large_pte(spte)); + drop_spte(kvm, sptep); + --kvm->stat.lpages; + return true; + }
- drop_spte(kvm, sptep); - --kvm->stat.lpages; - return true; + goto reset_spte; }
+ if (page_table_protect && spte_wp_by_dirty_log(spte)) + goto reset_spte; + + return false; + +reset_spte: rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte); spte = spte & ~PT_WRITABLE_MASK; + if (page_table_protect) + spte |= SPTE_WRITE_PROTECT; 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 page_table_protect) { u64 *sptep; struct rmap_iterator iter; @@ -1080,7 +1096,7 @@ __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, level > PT_PAGE_TABLE_LEVEL, - &write_protected)) { + &write_protected, page_table_protect)) { sptep = rmap_get_first(*rmapp, &iter); continue; } @@ -1109,7 +1125,7 @@ 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; @@ -1128,7 +1144,7 @@ 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; @@ -1179,7 +1195,8 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, unsigned long *rmapp, new_spte |= (u64)new_pfn << PAGE_SHIFT;
new_spte &= ~(PT_WRITABLE_MASK | SPTE_HOST_WRITEABLE | - shadow_accessed_mask | SPTE_ALLOW_WRITE); + shadow_accessed_mask | SPTE_ALLOW_WRITE | + SPTE_WRITE_PROTECT);
mmu_spte_clear_track_bits(sptep); mmu_spte_set(sptep, new_spte); @@ -2346,6 +2363,7 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, ret = 1; pte_access &= ~ACC_WRITE_MASK; spte &= ~PT_WRITABLE_MASK; + spte |= SPTE_WRITE_PROTECT; } }
@@ -3934,7 +3952,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) continue;
spte_write_protect(kvm, &pt[i], - is_large_pte(pt[i]), &flush); + is_large_pte(pt[i]), &flush, false); } } kvm_flush_remote_tlbs(kvm); -- 1.7.7.6
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