KVM: VMX: fix halt emulation while emulating invalid guest sate

The invalid guest state emulation loop does not check halt_request
which causes 100% cpu loop while guest is in halt and in invalid
state, but more serious issue is that this leaves halt_request set, so
random instruction emulated by vm86 #GP exit can be interpreted
as halt which causes guest hang. Fix both problems by handling
halt_request in emulation loop.

Reported-by: Tomas Papan <tomas.papan@gmail.com>
Tested-by: Tomas Papan <tomas.papan@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
CC: stable@vger.kernel.org
Signed-off-by: Gleb Natapov <gleb@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 25a791ed21c88057697eb06339f7066d8cfa63e2..260a9193955538b4fea743045b2f964b2736b24e 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5434,6 +5434,12 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
                        return 0;
                }
 
+               if (vcpu->arch.halt_request) {
+                       vcpu->arch.halt_request = 0;
+                       ret = kvm_emulate_halt(vcpu);
+                       goto out;
+               }
+
                if (signal_pending(current))
                        goto out;
                if (need_resched())