All of lore.kernel.org
 help / color / mirror / Atom feed
From: Wanpeng Li <kernellwp@gmail.com>
To: Sean Christopherson <seanjc@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v2 3/3] KVM: X86: Let's harden the ipi fastpath condition edge-trigger mode
Date: Wed, 9 Jun 2021 10:08:19 +0800	[thread overview]
Message-ID: <CANRm+CyecU4KYxNv77WGsiUB35r4TDNnLk7m_GLv=HvDCOGOLQ@mail.gmail.com> (raw)
In-Reply-To: <YL+cX8K3r7EWrk33@google.com>

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

  parent reply	other threads:[~2021-06-09  2:09 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07  7:19 [PATCH v2 1/3] KVM: LAPIC: Write 0 to TMICT should also cancel vmx-preemption timer Wanpeng Li
2021-06-07  7:19 ` [PATCH v2 2/3] KVM: LAPIC: Reset TMCCT during vCPU reset Wanpeng Li
2021-06-08 16:27   ` Paolo Bonzini
2021-06-09  2:15     ` Wanpeng Li
2021-06-09  5:51       ` Paolo Bonzini
2021-06-09  7:18         ` Wanpeng Li
2021-06-07  7:19 ` [PATCH v2 3/3] KVM: X86: Let's harden the ipi fastpath condition edge-trigger mode Wanpeng Li
2021-06-08 16:27   ` Paolo Bonzini
2021-06-08 16:35   ` Sean Christopherson
2021-06-08 17:40     ` Paolo Bonzini
2021-06-09  2:08     ` Wanpeng Li [this message]
2021-06-08 16:27 ` [PATCH v2 1/3] KVM: LAPIC: Write 0 to TMICT should also cancel vmx-preemption timer Paolo Bonzini

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CANRm+CyecU4KYxNv77WGsiUB35r4TDNnLk7m_GLv=HvDCOGOLQ@mail.gmail.com' \
    --to=kernellwp@gmail.com \
    --cc=jmattson@google.com \
    --cc=joro@8bytes.org \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=seanjc@google.com \
    --cc=vkuznets@redhat.com \
    --cc=wanpengli@tencent.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.