From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: linmiaohe <linmiaohe@huawei.com>
Cc: "kvm\@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
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Subject: Re: [PATCH] KVM: x86: don't notify userspace IOAPIC on edge-triggered interrupt EOI
Date: Tue, 18 Feb 2020 10:51:07 +0100 [thread overview]
Message-ID: <8736b89qb8.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <edf7454be5a743928cbc1bec5dce238d@huawei.com>
linmiaohe <linmiaohe@huawei.com> writes:
> Vitaly Kuznetsov <vkuznets@redhat.com> writes:
>>linmiaohe <linmiaohe@huawei.com> writes:
>>
>>> @@ -417,7 +417,7 @@ void kvm_scan_ioapic_routes(struct kvm_vcpu *vcpu,
>>>
>>> kvm_set_msi_irq(vcpu->kvm, entry, &irq);
>>>
>>> - if (irq.level &&
>>> + if (irq.trig_mode &&
>>> kvm_apic_match_dest(vcpu, NULL, APIC_DEST_NOSHORT,
>>> irq.dest_id, irq.dest_mode))
>>> __set_bit(irq.vector, ioapic_handled_vectors);
>>
>>Assuming Radim's comment (13db77347db1) is correct, the change in
>>3159d36ad799 looks wrong and your patch restores the status quo. Actually, kvm_set_msi_irq() always sets irq->level = 1 so checking it is pointless.
>>
>>Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>
> Thanks for review.
>
>>
>> (but it is actually possible that there's a buggy userspace out there which expects EOI notifications; we won't find out unless we try to fix the bug).
>>
>
> Yeh, there may be a buggy userspace hidden from this unexpected EOI notifications. It may not be worth enough to fix it as we may spend many time
> to catch the bug.
> Perhaps we should only remove the pointless checking of irq->level for cleanup. :)
I'm feeling brave so in case nobody expresses any particular concerns
let's just fix it :-)
--
Vitaly
next prev parent reply other threads:[~2020-02-18 9:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 1:41 [PATCH] KVM: x86: don't notify userspace IOAPIC on edge-triggered interrupt EOI linmiaohe
2020-02-18 9:51 ` Vitaly Kuznetsov [this message]
-- strict thread matches above, loose matches on Subject: below --
2020-02-19 1:39 linmiaohe
2020-02-14 2:32 linmiaohe
2020-02-17 16:12 ` Vitaly Kuznetsov
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