Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941185AbcJXPO0 (ORCPT ); Mon, 24 Oct 2016 11:14:26 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49450 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933483AbcJXPOY (ORCPT ); Mon, 24 Oct 2016 11:14:24 -0400 Date: Mon, 24 Oct 2016 17:14:18 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Paolo Bonzini 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 Subject: Re: [PATCH v4 5/5] x86, kvm: support vcpu preempted check Message-ID: <20161024151417.GC2247@potion> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 24 Oct 2016 15:14:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 964 Lines: 23 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. Using cached vcpu->arch.st.steal to avoid the read wouldn't be as good.