KVM/x86: Call smp_wmb() before increasing tlbs_dirty
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>
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index e0c2254..1d971c7 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -960,6 +960,12 @@
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 @@
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;
}