[PATCH 3/5] KVM: MMU: fix wrong not write protected sp report

Xiao Guangrong
2010-08-28T11:22:46Z

The audit code reports some sp not write protected in current code, it's just the
bug in audit_write_protection(), since:

- the invalid sp not need write protected
- using uninitialize local variable('gfn')
- call kvm_mmu_audit() out of mmu_lock's protection

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/mmu.c | 5 +++--
arch/x86/kvm/paging_tmpl.h | 3 ++-
2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1c784b9..68575dc 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -3708,16 +3708,17 @@ static void audit_write_protection(struct kvm_vcpu *vcpu)
struct kvm_memory_slot *slot;
unsigned long *rmapp;
u64 *spte;
- gfn_t gfn;

list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
if (sp->role.direct)
continue;
if (sp->unsync)
continue;
+ if (sp->role.invalid)
+ continue;

slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
- rmapp = &slot->rmap[gfn - slot->base_gfn];
+ rmapp = &slot->rmap[sp->gfn - slot->base_gfn];

spte = rmap_next(vcpu->kvm, rmapp, NULL);
while (spte) {
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index a4e8389..a0f2feb 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -504,7 +504,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
unsigned long mmu_seq;

pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
- kvm_mmu_audit(vcpu, "pre page fault");

r = mmu_topup_memory_caches(vcpu);
if (r)
@@ -542,6 +541,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
spin_lock(&vcpu->kvm->mmu_lock);
if (mmu_notifier_retry(vcpu, mmu_seq))
goto out_unlock;
+
+ kvm_mmu_audit(vcpu, "pre page fault");
kvm_mmu_free_some_pages(vcpu);
sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
level, &write_pt, pfn);
--
1.7.0.4