Re: KVM: MMU: nuke shadowed pgtable pages and pte's on memslot destruction

Marcelo Tosatti
2008-07-10T23:57:20Z

KVM: MMU: improve invalid shadow root page handling

Harden kvm_mmu_zap_page() against invalid root pages that
had been shadowed from memslots that are gone.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ff7cf63..7f57da6 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -930,14 +930,17 @@ static void kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
}
kvm_mmu_page_unlink_children(kvm, sp);
if (!sp->root_count) {
- if (!sp->role.metaphysical)
+ if (!sp->role.metaphysical && !sp->role.invalid)
unaccount_shadowed(kvm, sp->gfn);
hlist_del(&sp->hash_link);
kvm_mmu_free_page(kvm, sp);
} else {
+ int invalid = sp->role.invalid;
list_move(&sp->link, &kvm->arch.active_mmu_pages);
sp->role.invalid = 1;
kvm_reload_remote_mmus(kvm);
+ if (!sp->role.metaphysical && !invalid)
+ unaccount_shadowed(kvm, sp->gfn);
}
kvm_mmu_reset_last_pte_updated(kvm);
}