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X-CSE-ConnectionGUID: Stxz4/JBQSWOVUmK5wXeiw== X-CSE-MsgGUID: j+rgZYHHTweRBLHT5+joyg== X-IronPort-AV: E=McAfee;i="6800,10657,11536"; a="46301674" X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="46301674" Received: from orviesa006.jf.intel.com ([10.64.159.146]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2025 23:37:12 -0700 X-CSE-ConnectionGUID: qLVDycIETH2+Jr81JpgWUw== X-CSE-MsgGUID: gByn24WPQ+eRKatCAsKdSw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,221,1751266800"; d="scan'208";a="169565167" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.238.14]) ([10.124.238.14]) by orviesa006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Aug 2025 23:37:06 -0700 Message-ID: <8368132d-dc31-4820-99ba-b3af76a99d54@intel.com> Date: Fri, 29 Aug 2025 14:37:03 +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 v13 02/21] KVM: x86: Report XSS as to-be-saved if there are supported features To: Chao Gao , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, john.allen@amd.com, mingo@redhat.com, minipli@grsecurity.net, mlevitsk@redhat.com, pbonzini@redhat.com, rick.p.edgecombe@intel.com, seanjc@google.com, tglx@linutronix.de, weijiang.yang@intel.com, x86@kernel.org, xin@zytor.com References: <20250821133132.72322-1-chao.gao@intel.com> <20250821133132.72322-3-chao.gao@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20250821133132.72322-3-chao.gao@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/21/2025 9:30 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 > Signed-off-by: Chao Gao Reviewed-by: Xiaoyao Li > --- > 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 31a7e7ad310a..569583943779 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[] = { > @@ -7474,6 +7474,10 @@ 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; > }