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 9C934C433EF for ; Thu, 28 Oct 2021 14:09:20 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 48254610F8 for ; Thu, 28 Oct 2021 14:09:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 48254610F8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DFA3D4B1DD; Thu, 28 Oct 2021 10:09:19 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@redhat.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZnHhKEqEQGUA; 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bh=MHpIfrYfSW8Oruu5gZzONXfOs5cqhayPI05VEPrlFqI=; b=ZXK1SsScmTgtnETpIVi2QXHMMs18RzTZPLNJsMQPBJZrv9133Un6zEiD04wYDmRLk8iqrN iuZX4yT7S6TUZoHT9hESffo8pukWCq5lQV0yzXImlSkMPgQqKPN/CyfuhIr/OGE6dxfDS+ vegJ1oDUxlGxo3f0//TYGU5zmJ/np9g= 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-301-eJZbxn5mNyK61ySDSBCRrA-1; Thu, 28 Oct 2021 07:28:46 -0400 X-MC-Unique: eJZbxn5mNyK61ySDSBCRrA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CF9359F92B; Thu, 28 Oct 2021 11:28:42 +0000 (UTC) Received: from starship (unknown [10.40.194.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 108AF5DA61; Thu, 28 Oct 2021 11:28:30 +0000 (UTC) Message-ID: <643d9c249b5863f04290a6f047ea1a2d98bd75f9.camel@redhat.com> Subject: Re: [PATCH v2 27/43] KVM: VMX: Move Posted Interrupt ndst computation out of write loop 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 Date: Thu, 28 Oct 2021 14:28:29 +0300 In-Reply-To: <20211009021236.4122790-28-seanjc@google.com> References: <20211009021236.4122790-1-seanjc@google.com> <20211009021236.4122790-28-seanjc@google.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mailman-Approved-At: Thu, 28 Oct 2021 10:09:13 -0400 Cc: Wanpeng Li , kvm@vger.kernel.org, David Hildenbrand , linux-kernel@vger.kernel.org, Atish Patra , linux-riscv@lists.infradead.org, Claudio Imbrenda , kvmarm@lists.cs.columbia.edu, Joerg Roedel , kvm-ppc@vger.kernel.org, David Matlack , linux-arm-kernel@lists.infradead.org, Jim Mattson , Cornelia Huck , linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org, Vitaly Kuznetsov X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, 2021-10-08 at 19:12 -0700, Sean Christopherson wrote: > Hoist the CPU => APIC ID conversion for the Posted Interrupt descriptor > out of the loop to write the descriptor, preemption is disabled so the > CPU won't change, and if the APIC ID changes KVM has bigger problems. > > No functional change intended. Is preemption always disabled in vmx_vcpu_pi_load? vmx_vcpu_pi_load is called from vmx_vcpu_load, which is called indirectly from vcpu_load which is called from many ioctls, which userspace does. In these places I don't think that preemption is disabled. Best regards, Maxim Levitsky > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/vmx/posted_intr.c | 25 +++++++++++-------------- > 1 file changed, 11 insertions(+), 14 deletions(-) > > diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c > index fea343dcc011..2b2206339174 100644 > --- a/arch/x86/kvm/vmx/posted_intr.c > +++ b/arch/x86/kvm/vmx/posted_intr.c > @@ -51,17 +51,15 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu) > goto after_clear_sn; > } > > - /* The full case. */ > + /* The full case. Set the new destination and clear SN. */ > + dest = cpu_physical_id(cpu); > + if (!x2apic_mode) > + dest = (dest << 8) & 0xFF00; > + > do { > old.control = new.control = READ_ONCE(pi_desc->control); > > - dest = cpu_physical_id(cpu); > - > - if (x2apic_mode) > - new.ndst = dest; > - else > - new.ndst = (dest << 8) & 0xFF00; > - > + new.ndst = dest; > new.sn = 0; > } while (cmpxchg64(&pi_desc->control, old.control, > new.control) != old.control); > @@ -103,15 +101,14 @@ static void __pi_post_block(struct kvm_vcpu *vcpu) > WARN(pi_desc->nv != POSTED_INTR_WAKEUP_VECTOR, > "Wakeup handler not enabled while the vCPU was blocking"); > > + dest = cpu_physical_id(vcpu->cpu); > + if (!x2apic_mode) > + dest = (dest << 8) & 0xFF00; > + > do { > old.control = new.control = READ_ONCE(pi_desc->control); > > - dest = cpu_physical_id(vcpu->cpu); > - > - if (x2apic_mode) > - new.ndst = dest; > - else > - new.ndst = (dest << 8) & 0xFF00; > + new.ndst = dest; > > /* set 'NV' to 'notification vector' */ > new.nv = POSTED_INTR_VECTOR; _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm