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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id d15-20020a1c730f000000b00394975e14f4sm3750939wmb.8.2022.05.19.02.12.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 May 2022 02:12:12 -0700 (PDT) From: Vitaly Kuznetsov To: Maxim Levitsky Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , Michael Kelley , Siddharth Chandrasekaran , linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini Subject: Re: [PATCH v3 20/34] KVM: x86: KVM_REQ_TLB_FLUSH_CURRENT is a superset of KVM_REQ_HV_TLB_FLUSH too In-Reply-To: <6c9add3244d86080ccd8c3c72a37b9ee112d45b8.camel@redhat.com> References: <20220414132013.1588929-1-vkuznets@redhat.com> <20220414132013.1588929-21-vkuznets@redhat.com> <6c9add3244d86080ccd8c3c72a37b9ee112d45b8.camel@redhat.com> Date: Thu, 19 May 2022 11:12:11 +0200 Message-ID: <87mtfdubro.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org Maxim Levitsky writes: > On Thu, 2022-04-14 at 15:19 +0200, Vitaly Kuznetsov wrote: >> KVM_REQ_TLB_FLUSH_CURRENT is an even stronger operation than >> KVM_REQ_TLB_FLUSH_GUEST so KVM_REQ_HV_TLB_FLUSH needs not to be >> processed after it. >> >> Signed-off-by: Vitaly Kuznetsov >> --- >> arch/x86/kvm/x86.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index e5aec386d299..d3839e648ab3 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -3357,8 +3357,11 @@ static inline void kvm_vcpu_flush_tlb_current(struct kvm_vcpu *vcpu) >> */ >> void kvm_service_local_tlb_flush_requests(struct kvm_vcpu *vcpu) >> { >> - if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu)) >> + if (kvm_check_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu)) { >> kvm_vcpu_flush_tlb_current(vcpu); >> + if (kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu)) >> + kvm_hv_vcpu_empty_flush_tlb(vcpu); >> + } >> >> if (kvm_check_request(KVM_REQ_TLB_FLUSH_GUEST, vcpu)) { >> kvm_vcpu_flush_tlb_guest(vcpu); > > > I think that this patch should be moved near patch 1 and/or even squished with it. > Sure, will merge. This, however, made me think there's room for optimization here. In some cases, when both KVM_REQ_TLB_FLUSH_CURRENT and KVM_REQ_TLB_FLUSH_GUEST were requested, there's no need to flush twice, e.g. on SVM .flush_tlb_current == .flush_tlb_guest. I'll probably not go into this territory with this series as it's already fairly big, just something for the future. -- Vitaly