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

commit 8d76c49e9ffeee839bc0b7a3278a23f99101263e 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 <tomas.papan@gmail.com>
Tested-by: Tomas Papan <tomas.papan@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 407789b00e724af9cb0a19752ae788fbd26d486c..aac5ea7620fa0f91e50af1f3b1c28d849e6bf6a3 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4882,6 +4882,12 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu)
                if (err != EMULATE_DONE)
                        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())