On 07/13/2010 12:42 PM, Xiao Guangrong wrote:
In the speculative path, we should check guest pte's reserved bits just as
the real processor does
Reported-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx>
Signed-off-by: Xiao Guangrong<xiaoguangrong@xxxxxxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 8 ++++++++
arch/x86/kvm/paging_tmpl.h | 5 +++--
2 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b93b94f..9fc1524 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2783,6 +2783,9 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
break;
}
+ if (is_rsvd_bits_set(vcpu, gentry, PT_PAGE_TABLE_LEVEL))
+ gentry = 0;
+
mmu_guess_page_from_pte_write(vcpu, gpa, gentry);
spin_lock(&vcpu->kvm->mmu_lock);
if (atomic_read(&vcpu->kvm->arch.invlpg_counter) != invlpg_counter)
@@ -2851,6 +2854,11 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
while (npte--) {
entry = *spte;
mmu_pte_write_zap_pte(vcpu, sp, spte);
+
+ if (!!is_pae(vcpu) != sp->role.cr4_pae ||
+ is_nx(vcpu) != sp->role.nxe)
+ continue;
+
Do we also need to check cr0.wp? I think so.
if (gentry)
mmu_pte_write_new_pte(vcpu, sp, spte,&gentry);
Please move the checks to mmu_pte_write_new_pte(), it's a more logical
place.
It means the reserved bits check happens multiple times, but that's ok.
Also, you can use arch.mmu.base_role to compare:
static const kvm_mmu_page_role mask = { .level = -1U, .cr4_pae = 1,
... };
if ((sp->role.word ^ base_role.word) & mask.word)
return;
@@ -640,8 +640,9 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
return -EINVAL;
gfn = gpte_to_gfn(gpte);
- if (gfn != sp->gfns[i] ||
- !is_present_gpte(gpte) || !(gpte& PT_ACCESSED_MASK)) {
+ if (is_rsvd_bits_set(vcpu, gpte, PT_PAGE_TABLE_LEVEL) ||
+ gfn != sp->gfns[i] || !is_present_gpte(gpte) ||
+ !(gpte& PT_ACCESSED_MASK)) {
u64 nonpresent;
if (is_present_gpte(gpte) || !clear_unsync)
Eventually we have to reduce the number of paths. But lets fix things
first.
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
--
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