From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>
Subject: [PATCH v3 3/3] KVM: Check preempted_in_kernel for involuntary preemption
Date: Thu, 1 Aug 2019 11:30:14 +0800 [thread overview]
Message-ID: <1564630214-28442-3-git-send-email-wanpengli@tencent.com> (raw)
In-Reply-To: <1564630214-28442-1-git-send-email-wanpengli@tencent.com>
From: Wanpeng Li <wanpengli@tencent.com>
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>
---
virt/kvm/kvm_main.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3e1a509..58b9590 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2519,7 +2519,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (swait_active(&vcpu->wq) && !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;
@@ -4216,7 +4217,7 @@ 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);
@@ -4230,7 +4231,7 @@ 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);
--
2.7.4
next prev parent reply other threads:[~2019-08-01 3:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-01 3:30 [PATCH v3 1/3] KVM: Fix leak vCPU's VMCS value into other pCPU Wanpeng Li
2019-08-01 3:30 ` [PATCH v3 2/3] KVM: LAPIC: Don't need to wakeup vCPU twice afer timer fire Wanpeng Li
2019-08-01 3:30 ` Wanpeng Li [this message]
[not found] ` <20190801133133.955E4216C8@mail.kernel.org>
2019-08-02 0:46 ` [PATCH v3 1/3] KVM: Fix leak vCPU's VMCS value into other pCPU Wanpeng Li
2019-08-03 6:41 ` Paolo Bonzini
2019-08-05 2:04 ` Wanpeng Li
2019-08-03 6:36 ` Paolo Bonzini
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