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[91.219.240.2]) by smtp.gmail.com with ESMTPSA id j6sm31648430wrb.4.2020.03.25.02.33.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 25 Mar 2020 02:33:43 -0700 (PDT) From: Vitaly Kuznetsov To: Sean Christopherson , Paolo Bonzini Cc: Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Junaid Shahid , Liran Alon , Boris Ostrovsky , John Haxby , Miaohe Lin , Tom Lendacky Subject: Re: [PATCH v3 08/37] KVM: VMX: Skip global INVVPID fallback if vpid==0 in vpid_sync_context() In-Reply-To: <20200320212833.3507-9-sean.j.christopherson@intel.com> References: <20200320212833.3507-1-sean.j.christopherson@intel.com> <20200320212833.3507-9-sean.j.christopherson@intel.com> Date: Wed, 25 Mar 2020 10:33:41 +0100 Message-ID: <877dz87p8q.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sean Christopherson writes: > Skip the global INVVPID in the unlikely scenario that vpid==0 and the > SINGLE_CONTEXT variant of INVVPID is unsupported. If vpid==0, there's > no need to INVVPID as it's impossible to do VM-Enter with VPID enabled > and vmcs.VPID==0, i.e. there can't be any TLB entries for the vCPU with > vpid==0. The fact that the SINGLE_CONTEXT variant isn't supported is > irrelevant. > > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/vmx/ops.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/ops.h b/arch/x86/kvm/vmx/ops.h > index 45eaedee2ac0..33645a8e5463 100644 > --- a/arch/x86/kvm/vmx/ops.h > +++ b/arch/x86/kvm/vmx/ops.h > @@ -285,7 +285,7 @@ static inline void vpid_sync_context(int vpid) > { > if (cpu_has_vmx_invvpid_single()) > vpid_sync_vcpu_single(vpid); > - else > + else if (vpid != 0) > vpid_sync_vcpu_global(); > } Reviewed-by: Vitaly Kuznetsov (personally, I also prefer 'vpid !=0' to '!vpid', however, nested.c uses expressions like '&& !vmcs12->virtual_processor_id' instead...) -- Vitaly