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([2001:b07:6468:f312:8deb:6d34:4b78:b801]) by smtp.gmail.com with ESMTPSA id j145sm19845367wmj.12.2020.08.09.10.14.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 09 Aug 2020 10:14:15 -0700 (PDT) Subject: Re: [PATCH v3 2/2] x86/kvm: Expose new features for supported cpuid To: Cathy Zhang , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org Cc: sean.j.christopherson@intel.com, gregkh@linuxfoundation.org, tglx@linutronix.de, tony.luck@intel.com, dave.hansen@intel.com, kyung.min.park@intel.com, ricardo.neri-calderon@linux.intel.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, jpoimboe@redhat.com, ak@linux.intel.com, ravi.v.shankar@intel.com References: <1596959242-2372-1-git-send-email-cathy.zhang@intel.com> <1596959242-2372-3-git-send-email-cathy.zhang@intel.com> From: Paolo Bonzini Message-ID: Date: Sun, 9 Aug 2020 19:14:13 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <1596959242-2372-3-git-send-email-cathy.zhang@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 09/08/20 09:47, Cathy Zhang wrote: > Expose the SERIALIZE and TSX Suspend Load Address Tracking > features in KVM CPUID, so when running on processors which > support them, KVM could pass this information to guests and > they can make use of these features accordingly. > > SERIALIZE is a faster serializing instruction which does not modify > registers, arithmetic flags or memory, will not cause VM exit. It's > availability is indicated by CPUID.(EAX=7,ECX=0):ECX[bit 14]. > > TSX suspend load tracking instruction aims to give a way to choose > which memory accesses do not need to be tracked in the TSX read set. > It's availability is indicated as CPUID.(EAX=7,ECX=0):EDX[bit 16]. > > Those instructions are currently documented in the the latest "extensions" > manual (ISE). It will appear in the "main" manual (SDM) in the future. > > Signed-off-by: Cathy Zhang > Reviewed-by: Tony Luck > --- > Changes since v2: > * Merge two patches into a single one. (Luck, Tony) > * Add overview introduction for features. (Sean Christopherson) > * Refactor commit message to explain why expose feature bits. (Luck, Tony) > --- > arch/x86/kvm/cpuid.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 8a294f9..dcf48cc 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -341,7 +341,8 @@ void kvm_set_cpu_caps(void) > kvm_cpu_cap_mask(CPUID_7_EDX, > F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) | > F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) | > - F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) > + F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) | > + F(SERIALIZE) | F(TSXLDTRK) > ); > > /* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */ > TSXLDTRK is not going to be in 5.9 as far as I can see, so I split back again the patches (this is why I prefer them to be split, sorry Tony :)) and committed the SERIALIZE part. Paolo