From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v4 5/5] x86, kvm: support vcpu preempted check Date: Mon, 24 Oct 2016 17:18:36 +0200 Message-ID: <1a556fcf-e071-8c32-7a4b-ca7a2ffc17e9@redhat.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20161024151417.GC2247@potion> Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= 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 List-ID: 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! Thanks, Paolo > Using cached vcpu->arch.st.steal to avoid the read wouldn't be as good. >