From: Paolo Bonzini <pbonzini@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>,
Frederic Weisbecker <frederic@kernel.org>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
kvm@vger.kernel.org
Subject: Re: Async page fault delivered while irq are disabled?
Date: Fri, 20 Dec 2019 10:34:20 +0100 [thread overview]
Message-ID: <925b4dd2-7919-055e-0041-672dad8c082e@redhat.com> (raw)
In-Reply-To: <20191219190028.GB6439@linux.intel.com>
On 19/12/19 20:00, Sean Christopherson wrote:
>> And one last silly question, what about that line in
>> kvm_arch_can_inject_async_page_present:
>>
>> if (!(vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED))
>> return true;
>>
>> That looks weird, also it shortcuts the irqs_allowed() check.
>
> I wondered about that code as well :-). Definitely odd, but it would
> require the guest to disable async #PF after an async #PF is queued. Best
> guess is the idea is that it's the guest's problem if it disables async #PF
> on the fly.
>
When the guest disables async #PF all outstanding page faults are
cancelled by kvm_clear_async_pf_completion_queue. However, in case they
complete while in cancel_work_sync. you need to inject them even if
interrupts are disabled.
Paolo
next prev parent reply other threads:[~2019-12-20 9:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-19 15:28 Async page fault delivered while irq are disabled? Frederic Weisbecker
2019-12-19 15:57 ` Sean Christopherson
2019-12-19 16:15 ` Frederic Weisbecker
2019-12-19 19:00 ` Sean Christopherson
2019-12-20 9:34 ` Paolo Bonzini [this message]
2019-12-23 2:17 ` Frederic Weisbecker
2019-12-23 8:38 ` Paolo Bonzini
2019-12-26 17:28 ` Frederic Weisbecker
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