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KVM/x86: Call smp_wmb() before increasing tlbs_dirty

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Update spte before increasing tlbs_dirty to make sure no tlb flush
in lost after spte is zapped. This pairs with the barrier in the
kvm_flush_remote_tlbs().

Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Lan Tianyu 2016-03-13 11:10:27 +08:00 committed by Paolo Bonzini
parent a30a050916
commit 7bfdf21778
1 changed files with 11 additions and 0 deletions
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11
arch/x86/kvm/paging_tmpl.h
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@ -960,6 +960,12 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
return 0;
if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) {
/*
* Update spte before increasing tlbs_dirty to make
* sure no tlb flush is lost after spte is zapped; see
* the comments in kvm_flush_remote_tlbs().
*/
smp_wmb();
vcpu->kvm->tlbs_dirty++;
continue;
}
@ -975,6 +981,11 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
if (gfn != sp->gfns[i]) {
drop_spte(vcpu->kvm, &sp->spt[i]);
/*
* The same as above where we are doing
* prefetch_invalid_gpte().
*/
smp_wmb();
vcpu->kvm->tlbs_dirty++;
continue;
}