KVM: MMU: ignore zapped root pagetables
Mark zapped root pagetables as invalid and ignore such pages during lookup.
This is a problem with the cr3-target feature, where a zapped root table fools
the faulting code into creating a read-only mapping. The result is a lockup
if the instruction can't be emulated.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0dd038e..e8e6492 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2658,6 +2658,10 @@
kvm_x86_ops->guest_debug_pre(vcpu);
again:
+ if (vcpu->requests)
+ if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
+ kvm_mmu_unload(vcpu);
+
r = kvm_mmu_reload(vcpu);
if (unlikely(r))
goto out;
@@ -2689,6 +2693,14 @@
goto out;
}
+ if (vcpu->requests)
+ if (test_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests)) {
+ local_irq_enable();
+ preempt_enable();
+ r = 1;
+ goto out;
+ }
+
if (signal_pending(current)) {
local_irq_enable();
preempt_enable();