From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B3BD42D660E; Wed, 10 Sep 2025 09:22:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757496147; cv=none; b=XqVl5xabcNNFByZP0AIc1fqgzORKmhQ6mgJSQMnNidTsZSsFPUqwlYjT7L6mdzp/AmgYpBR/MDOCtNDnFh+E7T36PzmHX/0mwarfh1FCOto7VEoIkxxHYkXzhOoWJdtOTD6ydiU02H5a2lzMo8IkDNrFE/JdVeMclMxb6tsbMms= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757496147; c=relaxed/simple; bh=POyrcT+H2+ifea66XZUZbdvqwEmir36s8daZOE6z70c=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iGgLbhoQygFkk7u524OkhmEybJ+LHLV7jGgYFbADT0qVNDxdErTld5RwNGs1dQhsNpK+f7uUMVozOFieJ6A3EjVdxSGmEle7E8YavQtJee8os+FnHcnYcVtZHkOhQ13DoyAk9U52NpZw3OzzoI/il4sW246YqzSoRMv0XVQwXZM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=FRv5nYnh; arc=none smtp.client-ip=198.175.65.10 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="FRv5nYnh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1757496146; x=1789032146; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=POyrcT+H2+ifea66XZUZbdvqwEmir36s8daZOE6z70c=; b=FRv5nYnhXl4u6Ft0TxdamDG7fYA1Gf2CItf/QzniOot5AMFoxy1JAa79 nZkcf4i/McbBFmaFj8dLDUk6x0bmuDLFdmzFjc4dEMKlrjdyGvHlBJu6S QWxIrl76bgsAFNzvAn2PxQYcE+mhDbDWMzLVGo8IwPSoaQl8co3YtCli9 rREhZttTw/NRoxNkNf8EA/w9kVfukQwYW1r3Isd3xDeQGvtblURdFjCL7 kvqRyUh/spcvq2FTnzzNsrtweYq1OGVIKHqGwrNONh1AHf3PFVE6iG1p1 SUXcVNmnbL66a24Rr/1b4qYphC8/3OC56FQUN8nAK62Fxhjto0kCyyU9D w==; X-CSE-ConnectionGUID: fEW1SkgTRiO+CLXOoQHQtA== X-CSE-MsgGUID: 8V4Cw/SGRFKS908f/sfZzg== X-IronPort-AV: E=McAfee;i="6800,10657,11548"; a="77256362" X-IronPort-AV: E=Sophos;i="6.18,253,1751266800"; d="scan'208";a="77256362" Received: from orviesa002.jf.intel.com ([10.64.159.142]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Sep 2025 02:22:25 -0700 X-CSE-ConnectionGUID: cBdMZC66SdWbnoOpHHhlBg== X-CSE-MsgGUID: wLv2eARwRnuaAw1fUcBlow== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.18,253,1751266800"; d="scan'208";a="204103417" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.238.14]) ([10.124.238.14]) by orviesa002-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Sep 2025 02:22:19 -0700 Message-ID: Date: Wed, 10 Sep 2025 17:22:15 +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 03/22] KVM: x86: Check XSS validity against guest CPUIDs To: Chao Gao , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: 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 References: <20250909093953.202028-1-chao.gao@intel.com> <20250909093953.202028-4-chao.gao@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20250909093953.202028-4-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: > Maintain per-guest valid XSS bits and check XSS validity against them > rather than against KVM capabilities. This is to prevent bits that are > supported by KVM but not supported for a guest from being set. > > Opportunistically return KVM_MSR_RET_UNSUPPORTED on IA32_XSS MSR accesses > if guest CPUID doesn't enumerate X86_FEATURE_XSAVES. Since > KVM_MSR_RET_UNSUPPORTED takes care of host_initiated cases, drop the > host_initiated check. > > Signed-off-by: Chao Gao Reviewed-by: Xiaoyao Li > @@ -4011,15 +4011,14 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > } > break; > case MSR_IA32_XSS: > - if (!msr_info->host_initiated && > - !guest_cpuid_has(vcpu, X86_FEATURE_XSAVES)) > - return 1; > + if (!guest_cpuid_has(vcpu, X86_FEATURE_XSAVES)) > + return KVM_MSR_RET_UNSUPPORTED; > /* > * KVM supports exposing PT to the guest, but does not support > * IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than > * XSAVES/XRSTORS to save/restore PT MSRs. > */ Not an issue of this patch, there seems not the proper place to put above comment. > - if (data & ~kvm_caps.supported_xss) > + if (data & ~vcpu->arch.guest_supported_xss) > return 1; > vcpu->arch.ia32_xss = data; > vcpu->arch.cpuid_dynamic_bits_dirty = true;