Messages in this thread | | | From | Wanpeng Li <> | Date | Wed, 9 Jun 2021 10:08:19 +0800 | Subject | Re: [PATCH v2 3/3] KVM: X86: Let's harden the ipi fastpath condition edge-trigger mode |
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On Wed, 9 Jun 2021 at 00:35, Sean Christopherson <seanjc@google.com> wrote: > > On Mon, Jun 07, 2021, Wanpeng Li wrote: > > From: Wanpeng Li <wanpengli@tencent.com> > > > > Let's harden the ipi fastpath condition edge-trigger mode. > > Can you elaborate on the motivation for this patch? > > Intel's SDM states that the trigger mode is ignored for all IPIs except INIT, > and even clarifies that the local xAPIC will override the bit and send the IPI > as edge-triggered. > > AMD's APM on the other hand explicitly lists level-triggered Fixed IPIs as a > valid ICR combination. > > Regardless of which of the two conflicting specs we want KVM to emulate (which > is currently AMD), I don't see why the fastpath code should care, as I can't > find anything in the kvm_apic_send_ipi() path that would go awry if it's called > from the fastpath for a level-triggered IPI.
Fair enough.
Wanpeng
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