KVM: Check preempted_in_kernel for involuntary preemption (046ddeed) · Commits · 戴 / test

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>

virt/kvm/kvm_main.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -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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