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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id y7sm2571820wrr.56.2020.02.07.01.05.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Feb 2020 01:05:33 -0800 (PST) From: Vitaly Kuznetsov To: linmiaohe Cc: "kvm\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , "x86\@kernel.org" , "pbonzini\@redhat.com" , "rkrcmar\@redhat.com" , "sean.j.christopherson\@intel.com" , "wanpengli\@tencent.com" , "jmattson\@google.com" , "joro\@8bytes.org" , "tglx\@linutronix.de" , "mingo\@redhat.com" , "bp\@alien8.de" , "hpa\@zytor.com" Subject: Re: [PATCH] KVM: x86: remove duplicated KVM_REQ_EVENT request In-Reply-To: References: Date: Fri, 07 Feb 2020 10:05:32 +0100 Message-ID: <87h802g42r.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org linmiaohe writes: > Hi： > Vitaly Kuznetsov writes: >> linmiaohe writes: >>> From: Miaohe Lin >>> >>> The KVM_REQ_EVENT request is already made in kvm_set_rflags(). We >>> should not make it again. >>> kvm_rip_write(vcpu, ctxt->eip); >>> kvm_set_rflags(vcpu, ctxt->eflags); >>> - kvm_make_request(KVM_REQ_EVENT, vcpu); >> >> I would've actually done it the other way around and removed >> kvm_make_request() from kvm_set_rflags() as it is not an obvious behavior (e.g. why kvm_rip_write() doens't do that and kvm_set_rflags() does ?) adding kvm_make_request() to all call sites. >> >>In case this looks like too big of a change with no particular gain I'd suggest you at least leave a comment above kvm_set_rflags(), something like >> >>"kvm_make_request() also requests KVM_REQ_EVENT" > > I think adding kvm_make_request() to all call sites is too big without particular gain. And also leave a comment above > kvm_set_rflags() maybe isn't needed as rflags updates is an site that can trigger event injection. Please see commit > (3842d135ff24 KVM: Check for pending events before attempting injection) for detail. > > What do you think? I don't have a strong opinion on this and your change is correct so feel free to throw my Reviewed-by: Vitaly Kuznetsov -- Vitaly