Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752800AbdLMLiG (ORCPT ); Wed, 13 Dec 2017 06:38:06 -0500 Received: from mail-oi0-f68.google.com ([209.85.218.68]:46884 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751853AbdLMLiB (ORCPT ); Wed, 13 Dec 2017 06:38:01 -0500 X-Google-Smtp-Source: ACJfBouGmXYF4KGLXktBTmt8nWJwrVxEJe+RR0j3JCN9R6mxvqZ73Ct7M4jmHubGbbyDdaANrjhhmw7Jr2sAvjbOVXA= MIME-Version: 1.0 In-Reply-To: <3fb56993-3bb6-442c-f12e-0c99c06ef5c2@redhat.com> References: <1513128784-5924-1-git-send-email-wanpeng.li@hotmail.com> <1513128784-5924-2-git-send-email-wanpeng.li@hotmail.com> <3fb56993-3bb6-442c-f12e-0c99c06ef5c2@redhat.com> From: Wanpeng Li Date: Wed, 13 Dec 2017 19:38:00 +0800 Message-ID: Subject: Re: [PATCH v8 1/4] KVM: X86: Add vCPU running/preempted state To: David Hildenbrand Cc: "linux-kernel@vger.kernel.org" , kvm , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Peter Zijlstra , Wanpeng Li Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBDBcBdw005856 Content-Length: 1496 Lines: 39 2017-12-13 18:20 GMT+08:00 David Hildenbrand : > On 13.12.2017 02:33, Wanpeng Li wrote: >> From: Wanpeng Li >> >> This patch reuses the preempted field in kvm_steal_time, and will export >> the vcpu running/pre-empted information to the guest from host. This will >> enable guest to intelligently send ipi to running vcpus and set flag for >> pre-empted vcpus. This will prevent waiting for vcpus that are not running. >> >> Cc: Paolo Bonzini >> Cc: Radim Krčmář >> Cc: Peter Zijlstra >> Signed-off-by: Wanpeng Li >> --- >> arch/x86/include/uapi/asm/kvm_para.h | 3 +++ >> arch/x86/kernel/kvm.c | 2 +- >> arch/x86/kvm/x86.c | 4 ++-- >> 3 files changed, 6 insertions(+), 3 deletions(-) >> >> diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h >> index 09cc064..763b692 100644 >> --- a/arch/x86/include/uapi/asm/kvm_para.h >> +++ b/arch/x86/include/uapi/asm/kvm_para.h >> @@ -51,6 +51,9 @@ struct kvm_steal_time { >> __u32 pad[11]; >> }; >> >> +#define KVM_VCPU_NOT_PREEMPTED (0 << 0) >> +#define KVM_VCPU_PREEMPTED (1 << 0) > > Is it really helpful to have two flags? > > Just use KVM_VCPU_PREEMPTED and clear that one in record_steal_time() I think it is fine since there is a third flag introduced in patch 2/4, it is more clear currently. Regards, Wanpeng Li