From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3t2wT36B6mzDvgn for ; Tue, 25 Oct 2016 12:25:43 +1100 (AEDT) Received: from pps.filterd (m0098414.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.17/8.16.0.17) with SMTP id u9P1NRBa016920 for ; Mon, 24 Oct 2016 21:25:41 -0400 Received: from e23smtp07.au.ibm.com (e23smtp07.au.ibm.com [202.81.31.140]) by mx0b-001b2d01.pphosted.com with ESMTP id 269vdm2mpe-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 24 Oct 2016 21:25:41 -0400 Received: from localhost by e23smtp07.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 25 Oct 2016 11:25:37 +1000 Received: from d23relay08.au.ibm.com (d23relay08.au.ibm.com [9.185.71.33]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 371992BB0054 for ; Tue, 25 Oct 2016 12:25:34 +1100 (EST) Received: from d23av05.au.ibm.com (d23av05.au.ibm.com [9.190.234.119]) by d23relay08.au.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u9P1PYQP19005498 for ; Tue, 25 Oct 2016 12:25:34 +1100 Received: from d23av05.au.ibm.com (localhost [127.0.0.1]) by d23av05.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u9P1PWLo014323 for ; Tue, 25 Oct 2016 12:25:34 +1100 Subject: Re: [PATCH v4 5/5] x86, kvm: support vcpu preempted check To: Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <1476872416-42752-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> <1476872416-42752-6-git-send-email-xinhui.pan@linux.vnet.ibm.com> <20161019172403.GA9240@potion> <20161024151417.GC2247@potion> <1a556fcf-e071-8c32-7a4b-ca7a2ffc17e9@redhat.com> Cc: Pan Xinhui , linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, linux-s390@vger.kernel.org, xen-devel-request@lists.xenproject.org, kvm@vger.kernel.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, mingo@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, will.deacon@arm.com, kernellwp@gmail.com, jgross@suse.com, bsingharora@gmail.com, boqun.feng@gmail.com, borntraeger@de.ibm.com From: Pan Xinhui Date: Tue, 25 Oct 2016 09:25:37 +0800 MIME-Version: 1.0 In-Reply-To: <1a556fcf-e071-8c32-7a4b-ca7a2ffc17e9@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Message-Id: <2f37742f-6839-1ef4-0838-05fb7222f14a@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 在 2016/10/24 23:18, Paolo Bonzini 写道: > > > On 24/10/2016 17:14, Radim Krčmář wrote: >> 2016-10-24 16:39+0200, Paolo Bonzini: >>> On 19/10/2016 19:24, Radim Krčmář wrote: >>>>>> + if (vcpu->arch.st.msr_val & KVM_MSR_ENABLED) >>>>>> + if (kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.st.stime, >>>>>> + &vcpu->arch.st.steal, >>>>>> + sizeof(struct kvm_steal_time)) == 0) { >>>>>> + vcpu->arch.st.steal.preempted = 1; >>>>>> + kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime, >>>>>> + &vcpu->arch.st.steal, >>>>>> + sizeof(struct kvm_steal_time)); >>>>>> + } >>>> Please name this block of code. Something like >>>> kvm_steal_time_set_preempted(vcpu); >>> >>> While at it: >>> >>> 1) the kvm_read_guest_cached is not necessary. You can rig the call to >>> kvm_write_guest_cached so that it only writes vcpu->arch.st.steal.preempted. >> >> I agree. kvm_write_guest_cached() always writes from offset 0, so we'd >> want a new function that allows to specify a starting offset. > > Yeah, let's leave it for a follow-up then! > I think I can make a having-offset version. :) > Thanks, > > Paolo > >> Using cached vcpu->arch.st.steal to avoid the read wouldn't be as good. >> >