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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id oz39-20020a170906cd2700b00988b2050f47sm3235667ejb.20.2023.06.26.06.03.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jun 2023 06:03:13 -0700 (PDT) Date: Mon, 26 Jun 2023 15:03:12 +0200 From: Igor Mammedov To: Tao Su Cc: qemu-devel@nongnu.org, pbonzini@redhat.com, xiaoyao.li@intel.com, lei4.wang@intel.com, qian.wen@intel.com Subject: Re: [PATCH 3/7] target/i386: Allow MCDT_NO if host supports Message-ID: <20230626150312.5edefe7b@imammedo.users.ipa.redhat.com> In-Reply-To: <20230616032311.19137-4-tao1.su@linux.intel.com> References: <20230616032311.19137-1-tao1.su@linux.intel.com> <20230616032311.19137-4-tao1.su@linux.intel.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 16 Jun 2023 11:23:07 +0800 Tao Su wrote: > MCDT_NO bit indicates HW contains the security fix and doesn't need to > be mitigated to avoid data-dependent behaviour for certain instructions. > It needs no hypervisor support. Treat it as supported regardless of what > KVM reports. > > Signed-off-by: Tao Su > Reviewed-by: Xiaoyao Li > --- > target/i386/kvm/kvm.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c > index de531842f6..4defd8b479 100644 > --- a/target/i386/kvm/kvm.c > +++ b/target/i386/kvm/kvm.c > @@ -432,6 +432,11 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, > uint32_t eax; > host_cpuid(7, 1, &eax, &unused, &unused, &unused); > ret |= eax & (CPUID_7_1_EAX_FZRM | CPUID_7_1_EAX_FSRS | CPUID_7_1_EAX_FSRC); > + } else if (function == 7 && index == 2 && reg == R_EDX) { > + /* Not new instructions, just an optimization. */ comment doesn't make much sense to me, just drop it or describe what MCDT_NO is/mitigates. > + uint32_t edx; > + host_cpuid(7, 2, &unused, &unused, &unused, &edx); > + ret |= edx & CPUID_7_2_EDX_MCDT_NO; > } else if (function == 0xd && index == 0 && > (reg == R_EAX || reg == R_EDX)) { > /*