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authorWanpeng Li <wanpengli@tencent.com>2019-08-01 11:30:14 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2019-08-05 12:55:46 +0200
commit046ddeed0461b5d270470c253cbb321103d048b6 (patch)
tree3adf95674f267b4e056b56bd8227dde6a9eebfc6 /virt
parenta48d06f9b7cedbb8ad7804d1720168b7ee6a34e7 (diff)
KVM: Check preempted_in_kernel for involuntary preemption
preempted_in_kernel is updated in preempt_notifier when involuntary preemption ocurrs, it can be stale when the voluntarily preempted vCPUs are taken into account by kvm_vcpu_on_spin() loop. This patch lets it just check preempted_in_kernel for involuntary preemption. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Wanpeng Li <wanpengli@tencent.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 887f3b0c2b60..ed061d8a457c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2508,7 +2508,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu))
continue;
- if (yield_to_kernel_mode && !kvm_arch_vcpu_in_kernel(vcpu))
+ if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
+ !kvm_arch_vcpu_in_kernel(vcpu))
continue;
if (!kvm_vcpu_eligible_for_directed_yield(vcpu))
continue;
@@ -4205,7 +4206,7 @@ static void kvm_sched_in(struct preempt_notifier *pn, int cpu)
{
struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
- vcpu->preempted = false;
+ WRITE_ONCE(vcpu->preempted, false);
WRITE_ONCE(vcpu->ready, false);
kvm_arch_sched_in(vcpu, cpu);
@@ -4219,7 +4220,7 @@ static void kvm_sched_out(struct preempt_notifier *pn,
struct kvm_vcpu *vcpu = preempt_notifier_to_vcpu(pn);
if (current->state == TASK_RUNNING) {
- vcpu->preempted = true;
+ WRITE_ONCE(vcpu->preempted, true);
WRITE_ONCE(vcpu->ready, true);
}
kvm_arch_vcpu_put(vcpu);

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