KVM: x86: check for cr3 validity in mmu_alloc_roots

Verify the cr3 address stored in vcpu->arch.cr3 points to an existant
memslot. If not, inject a triple fault.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d2a4eca..3244437 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4568,6 +4568,7 @@
 void kvm_arch_flush_shadow(struct kvm *kvm)
 {
 	kvm_mmu_zap_all(kvm);
+	kvm_reload_remote_mmus(kvm);
 }
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)