When emulating HLT and a wake event is already pending, explicitly mark
the vCPU RUNNABLE (via kvm_set_mp_state()) instead of assuming the vCPU is
already in the appropriate state. Barring a KVM bug, it should be
impossible for the vCPU to be in a non-RUNNABLE state, but there is no
advantage to relying on that to hold true, and ensuring the vCPU is made
RUNNABLE avoids non-deterministic behavior with respect to pv_unhalted.
E.g. if the vCPU is not already RUNNABLE, then depending on when
pv_unhalted is set, KVM could either leave the vCPU in the non-RUNNABLE
state (set before __kvm_emulate_halt()), or transition the vCPU to HALTED
and then RUNNABLE (pv_unhalted set after the kvm_vcpu_has_events() check).
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 58b82d6fd77c..7f5abdaab935 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11310,9 +11310,8 @@ static int __kvm_emulate_halt(struct kvm_vcpu *vcpu, int state, int reason)
++vcpu->stat.halt_exits;
if (lapic_in_kernel(vcpu)) {
if (kvm_vcpu_has_events(vcpu))
- vcpu->arch.pv.pv_unhalted = false;
- else
- kvm_set_mp_state(vcpu, state);
+ state = KVM_MP_STATE_RUNNABLE;
+ kvm_set_mp_state(vcpu, state);
return 1;
} else {
vcpu->run->exit_reason = reason;
base-commit: fed48e2967f402f561d80075a20c5c9e16866e53
--
2.48.1.658.g4767266eb4-goog
