From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 83E48C433F5 for ; Thu, 28 Oct 2021 09:12:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6477860724 for ; Thu, 28 Oct 2021 09:12:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229835AbhJ1JPJ (ORCPT ); Thu, 28 Oct 2021 05:15:09 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:52698 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229626AbhJ1JPI (ORCPT ); Thu, 28 Oct 2021 05:15:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1635412361; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=l1MWdjra8eZcIIlx8zcoZvMR0jtyOa/xjrbhOVDWvpc=; b=Xzb4XGeOkwTXmzNy13WrmFr7AjQ2uTkTimS0KesOtRMvLcRtIfpVMjHKQoZuGw36ZKOjGX uOk1iWIvHwVrE7iYLYGsVcGzrvbIB2eVr0qlwy35CCuQh1mhhMjCTdYUVeoRQF6lCuuCNd olHLeh2pJScT+4mj2tzZPtMR6CFGf8Q= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-547-sp4eSFtgN52tnt6kECXjIQ-1; Thu, 28 Oct 2021 05:12:40 -0400 X-MC-Unique: sp4eSFtgN52tnt6kECXjIQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id EE71D1966321; Thu, 28 Oct 2021 09:12:36 +0000 (UTC) Received: from starship (unknown [10.40.194.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4625A5F707; Thu, 28 Oct 2021 09:12:15 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2 20/43] KVM: VMX: Skip Posted Interrupt updates if APICv is hard disabled From: Maxim Levitsky To: Sean Christopherson , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , Oliver Upton , Jing Zhang Date: Thu, 28 Oct 2021 12:12:13 +0300 In-Reply-To: <20211009021236.4122790-21-seanjc@google.com> References: <20211009021236.4122790-1-seanjc@google.com> <20211009021236.4122790-21-seanjc@google.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Fri, 2021-10-08 at 19:12 -0700, Sean Christopherson wrote: > Explicitly skip posted interrupt updates if APICv is disabled in all of > KVM, or if the guest doesn't have an in-kernel APIC. The PI descriptor > is kept up-to-date if APICv is inhibited, e.g. so that re-enabling APICv > doesn't require a bunch of updates, but neither the module param nor the > APIC type can be changed on-the-fly. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/vmx/posted_intr.c | 11 +++++++---- > 1 file changed, 7 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > index 3263056784f5..351666c41bbc 100644 > --- a/arch/x86/kvm/vmx/posted_intr.c > +++ b/arch/x86/kvm/vmx/posted_intr.c > @@ -28,11 +28,14 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) > unsigned int dest; > > /* > - * In case of hot-plug or hot-unplug, we may have to undo > - * vmx_vcpu_pi_put even if there is no assigned device. And we > - * always keep PI.NDST up to date for simplicity: it makes the > - * code easier, and CPU migration is not a fast path. > + * To simplify hot-plug and dynamic toggling of APICv, keep PI.NDST and > + * PI.SN up-to-date even if there is no assigned device or if APICv is > + * deactivated due to a dynamic inhibit bit, e.g. for Hyper-V's SyncIC. > */ > + if (!enable_apicv || !lapic_in_kernel(vcpu)) > + return; > + > + /* Nothing to do if PI.SN==0 and the vCPU isn't being migrated. */ > if (!pi_test_sn(pi_desc) && vcpu->cpu == cpu) > return; > Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky