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

commit 8d76c49 upstream.

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 <[email protected]>
Tested-by: Tomas Papan <[email protected]>
Reviewed-by: Paolo Bonzini <[email protected]>
Signed-off-by: Gleb Natapov <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>

Author: Gleb Natapov

arch/x86/kvm/vmx.c

@@ -5059,6 +5059,12 @@ 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())