Messages in this thread | | | From | Nadav Amit <> | Subject | Re: [PATCH v2 2/2] KVM: LAPIC: Don't need to clear IPI delivery status in x2apic mode | Date | Wed, 1 Apr 2020 17:40:03 +0000 |
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> On Mar 31, 2020, at 11:46 PM, Wanpeng Li <kernellwp@gmail.com> wrote: > > Cc more people, > On Wed, 1 Apr 2020 at 08:35, Paolo Bonzini <pbonzini@redhat.com> wrote: >> On 01/04/20 02:19, Wanpeng Li wrote: >>> - /* No delay here, so we always clear the pending bit */ >>> - val &= ~(1 << 12); >>> + /* Immediately clear Delivery Status in xAPIC mode */ >>> + if (!apic_x2apic_mode(apic)) >>> + val &= ~(1 << 12); >> >> This adds a conditional, and the old behavior was valid according to the >> SDM: "software should not assume the value returned by reading the ICR >> is the last written value". > > Nadav, Sean, what do you think?
I do not know. But if you write a KVM unit-test, I can run it on bare-metal and give you feedback about how it behaves.
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