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([2001:b07:6468:f312:652c:29a6:517b:66d9]) by smtp.gmail.com with ESMTPSA id x11sm391189wmg.46.2020.02.12.03.55.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 12 Feb 2020 03:55:30 -0800 (PST) Subject: Re: [PATCH v2] KVM: apic: reuse smp_wmb() in kvm_make_request() To: linmiaohe , rkrcmar@redhat.com, sean.j.christopherson@intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org References: <1581088927-3269-1-git-send-email-linmiaohe@huawei.com> From: Paolo Bonzini Message-ID: <4202948e-1c12-9ab0-5bba-d63846da8001@redhat.com> Date: Wed, 12 Feb 2020 12:55:36 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <1581088927-3269-1-git-send-email-linmiaohe@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/02/20 16:22, linmiaohe wrote: > From: Miaohe Lin > > kvm_make_request() provides smp_wmb() so pending_events changes are > guaranteed to be visible. > > Signed-off-by: Miaohe Lin > Reviewed-by: Vitaly Kuznetsov > --- > v1->v2: > Collected Vitaly's R-b > Use Vitaly's alternative wording > Drop unnecessary comment as suggested by Sean Christopherson > --- > arch/x86/kvm/lapic.c | 3 --- > 1 file changed, 3 deletions(-) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index eafc631d305c..afcd30d44cbb 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -1080,9 +1080,6 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, > result = 1; > /* assumes that there are only KVM_APIC_INIT/SIPI */ > apic->pending_events = (1UL << KVM_APIC_INIT); > - /* make sure pending_events is visible before sending > - * the request */ > - smp_wmb(); > kvm_make_request(KVM_REQ_EVENT, vcpu); > kvm_vcpu_kick(vcpu); > } > Queued, thanks. Paolo