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X-CSE-ConnectionGUID: Z2Wc160yTGul6Wk4XwdAXA== X-CSE-MsgGUID: TA8z09QuSqSkFgQKpxznrQ== X-IronPort-AV: E=McAfee;i="6800,10657,11531"; a="59960569" X-IronPort-AV: E=Sophos;i="6.17,312,1747724400"; d="scan'208";a="59960569" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by orvoesa110.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Sep 2025 23:52:39 -0700 X-CSE-ConnectionGUID: 1DLSL7J7R9Kr+mYeZY1wJA== X-CSE-MsgGUID: SJJ63r95S3639eCF7AT+pA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,256,1751266800"; d="scan'208";a="172899554" Received: from unknown (HELO [10.238.0.107]) ([10.238.0.107]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Sep 2025 23:52:34 -0700 Message-ID: <708d43af-3d87-4412-896b-1fbac1ef81b2@linux.intel.com> Date: Thu, 11 Sep 2025 14:52:31 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v14 02/22] KVM: x86: Report XSS as to-be-saved if there are supported features To: Chao Gao Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, acme@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, john.allen@amd.com, mingo@kernel.org, mingo@redhat.com, minipli@grsecurity.net, mlevitsk@redhat.com, namhyung@kernel.org, pbonzini@redhat.com, prsampat@amd.com, rick.p.edgecombe@intel.com, seanjc@google.com, shuah@kernel.org, tglx@linutronix.de, weijiang.yang@intel.com, x86@kernel.org, xin@zytor.com, xiaoyao.li@intel.com References: <20250909093953.202028-1-chao.gao@intel.com> <20250909093953.202028-3-chao.gao@intel.com> Content-Language: en-US From: Binbin Wu In-Reply-To: <20250909093953.202028-3-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/9/2025 5:39 PM, Chao Gao wrote: > From: Sean Christopherson > > Add MSR_IA32_XSS to list of MSRs reported to userspace if supported_xss > is non-zero, i.e. KVM supports at least one XSS based feature. > > Before enabling CET virtualization series, guest IA32_MSR_XSS is > guaranteed to be 0, i.e., XSAVES/XRSTORS is executed in non-root mode > with XSS == 0, which equals to the effect of XSAVE/XRSTOR. > > Signed-off-by: Sean Christopherson > Signed-off-by: Yang Weijiang > Reviewed-by: Maxim Levitsky > Reviewed-by: Chao Gao > Tested-by: Mathias Krause > Tested-by: John Allen > Tested-by: Rick Edgecombe > Reviewed-by: Xiaoyao Li > Signed-off-by: Chao Gao Reviewed-by: Binbin Wu > --- > arch/x86/kvm/x86.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index f32d3edfc7b1..47b60f275fd7 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -335,7 +335,7 @@ static const u32 msrs_to_save_base[] = { > MSR_IA32_RTIT_ADDR3_A, MSR_IA32_RTIT_ADDR3_B, > MSR_IA32_UMWAIT_CONTROL, > > - MSR_IA32_XFD, MSR_IA32_XFD_ERR, > + MSR_IA32_XFD, MSR_IA32_XFD_ERR, MSR_IA32_XSS, > }; > > static const u32 msrs_to_save_pmu[] = { > @@ -7470,6 +7470,10 @@ static void kvm_probe_msr_to_save(u32 msr_index) > if (!(kvm_get_arch_capabilities() & ARCH_CAP_TSX_CTRL_MSR)) > return; > break; > + case MSR_IA32_XSS: > + if (!kvm_caps.supported_xss) > + return; > + break; > default: > break; > }