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X-CSE-ConnectionGUID: RAusM2ZmQsepLMp5pMtIJg== X-CSE-MsgGUID: 4e2LKv+PRnKP/oxLQiBwkw== X-IronPort-AV: E=McAfee;i="6800,10657,11770"; a="89019155" X-IronPort-AV: E=Sophos;i="6.23,204,1770624000"; d="scan'208";a="89019155" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2026 11:49:26 -0700 X-CSE-ConnectionGUID: 5ZDx2DgGR6uP7a/1foAwpg== X-CSE-MsgGUID: RzluhfUuSiGyItnX+We7hw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.23,204,1770624000"; d="scan'208";a="235792341" Received: from sghuge-mobl2.amr.corp.intel.com (HELO [10.125.108.208]) ([10.125.108.208]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Apr 2026 11:49:26 -0700 Message-ID: <0fa94f46-4cd8-4e28-a080-1517fccb1578@intel.com> Date: Tue, 28 Apr 2026 11:49:24 -0700 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 1/2] KVM: TDX: Allow TDs to read MSR_IA32_PLATFORM_ID To: Binbin Wu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org Cc: pbonzini@redhat.com, seanjc@google.com, kas@kernel.org, rick.p.edgecombe@intel.com, vishal.l.verma@intel.com, xiaoyao.li@intel.com, chao.gao@intel.com References: <20260428024746.1040531-1-binbin.wu@linux.intel.com> <20260428024746.1040531-2-binbin.wu@linux.intel.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/27/26 19:47, Binbin Wu wrote: > Linux kernel reads MSR_IA32_PLATFORM_ID during init since commit > d8630b67ca1e ("x86/cpu: Add platform ID to CPU info structure"). KVM > already supports this MSR on read for normal VMs by returning 0. > Without support for this MSR, TDs get unchecked MSR access errors. NAK from me on this. The platform ID is used for one thing and one thing only: microcode updates. Those updates are solely the domain of the bare-metal OS. The (guest) kernel code that's even trying to touch this MSR is buggy and insane. We need to turn that code it off when X86_FEATURE_HYPERVISOR==1. There's already a patch floating around to do that. Please don't add more smoke and mirrors.