From: Chao Gao <chao.gao@intel.com>
To: Sean Christopherson <seanjc@google.com>
Cc: "Longpeng (Mike,
Cloud Infrastructure Service Product Dept.)"
<longpeng2@huawei.com>,
"pbonzini@redhat.com" <pbonzini@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Gonglei (Arei)" <arei.gonglei@huawei.com>,
Huangzhichao <huangzhichao@huawei.com>,
Wanpeng Li <wanpengli@tencent.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: The vcpu won't be wakened for a long time
Date: Wed, 22 Dec 2021 14:07:36 +0800 [thread overview]
Message-ID: <20211222060735.GA22521@gao-cwp> (raw)
In-Reply-To: <YcHyReHoF+qjIVTy@google.com>
On Tue, Dec 21, 2021 at 03:27:01PM +0000, Sean Christopherson wrote:
>On Sat, Dec 18, 2021, Longpeng (Mike, Cloud Infrastructure Service Product Dept.) wrote:
>> > Hmm, that strongly suggests the "vcpu != kvm_get_running_vcpu()" is at fault.
>> > Can you try running with the below commit? It's currently sitting in kvm/queue,
>> > but not marked for stable because I didn't think it was possible for the check
>> > to a cause a missed wake event in KVM's current code base.
>> >
>>
>> The below commit can fix the bug, we have just completed the tests.
>> Thanks.
>
>Aha! Somehow I missed this call chain when analyzing the change.
>
> irqfd_wakeup()
> |
> |->kvm_arch_set_irq_inatomic()
> |
> |-> kvm_irq_delivery_to_apic_fast()
> |
> |-> kvm_apic_set_irq()
>
>
>Paolo, can the changelog be amended to the below, and maybe even pull the commit
>into 5.16?
>
>
>KVM: VMX: Wake vCPU when delivering posted IRQ even if vCPU == this vCPU
>
>Drop a check that guards triggering a posted interrupt on the currently
>running vCPU,
Can we move (add) this check to kvm_vcpu_trigger_posted_interrupt()?
if (vcpu->mode == IN_GUEST_MODE) {
[...]
- apic->send_IPI_mask(get_cpu_mask(vcpu->cpu), pi_vec);
+ if (vcpu != kvm_get_running_vcpu())
+ apic->send_IPI_mask(get_cpu_mask(vcpu->cpu), pi_vec);
return true;
It can achieve the purpose of the original patch without (re-)introducing
this bug.
next prev parent reply other threads:[~2021-12-22 5:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-14 13:55 The vcpu won't be wakened for a long time Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-12-14 17:36 ` Sean Christopherson
2021-12-16 14:03 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-12-16 15:42 ` Sean Christopherson
2021-12-17 2:11 ` Wanpeng Li
2021-12-17 5:51 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-12-18 9:08 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-12-21 15:27 ` Sean Christopherson
2021-12-21 15:34 ` Paolo Bonzini
2021-12-22 6:07 ` Chao Gao [this message]
2021-12-22 15:44 ` Sean Christopherson
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