From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.7]) (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 63B7F3D3324; Thu, 24 Sep 2026 02:05:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.7 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790215555; cv=none; b=jWdD662Fyhn6mBsiWjvhFfYOmL/evLkBoF2njoKsokMwA5SQbM43xyaPQFFQTmOXOS2CLLbS5dYgoqWbjmAtLpTP3djyH+IyWP35rQXvH3fBjz2815VOkmCtCE2OA6H8fqf2NzsZw1/I2baiuzUSlmdsSCLA/FkdggJCFGaJsPg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790215555; c=relaxed/simple; bh=E+8rml4eeQ1gQkwzsqlnlOO8AmrtYgESx0n8qBTNVMc=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=U4WHxRNzUmhpGsnyftGcPkFH34mb5kISCSFLcJ+Q3nFuGDkgM1MkzyRGRbHRCryT0igwS61Bm2Ni6psU418/PIy6V9ZYfpZyZw+gSiOofk1AQALXXMnHZXnk4WRvQWLm1Ca2eJKWcFbusmCmPGZTsK+XTY9FMoNPwqSFnu6T7VM= 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=gntvr7O8; arc=none smtp.client-ip=192.198.163.7 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="gntvr7O8" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790215553; x=1821751553; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=E+8rml4eeQ1gQkwzsqlnlOO8AmrtYgESx0n8qBTNVMc=; b=gntvr7O8CF6D+J7REa3e6U2n/IIuEGvrNmzduqRUNfO3D12wKD38st9t RTnRvRJaQE7SdLNRtSQpcvoDE6hv/mUYvwGMWRwTi7gCrWP+/gpDVvce7 YHpe916VqnmMD1nJiCRDL1cxYGJB2FISCoNij4dlRrAd/7iRUM+Fxg+x9 M04mzmw+dpO48qzhzRqfKz7LNSCq75oruyfHQTuCXCluilUA4OKJZZd89 sI5qb+nnZAOeTU6SP/7myIldZmq13RxmueEqipMuCEDIj6XA0NexgQbaN 0iZJCsKGkyG7EsTizttK0twW2aVMM9Qac8Ec67i1TxpH3b2ZJXkVtn5i5 Q==; X-CSE-ConnectionGUID: cGp6iO3FSaiI1dcornTyrQ== X-CSE-MsgGUID: v7VGGcUoSVWSl4mqp+h0HA== X-IronPort-AV: E=McAfee;i="6800,10657,11914"; a="116492718" X-IronPort-AV: E=Sophos;i="6.27,119,1787036400"; d="scan'208";a="116492718" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by fmvoesa101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2026 19:05:52 -0700 X-CSE-ConnectionGUID: zvsnqQR1T1OtYIoeUU+U3A== X-CSE-MsgGUID: O5S8Q6WyRjirXrSwPN0jhQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,119,1787036400"; d="scan'208";a="278601304" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.240.119]) ([10.124.240.119]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Sep 2026 19:05:48 -0700 Message-ID: <13ea0c8b-756e-4bf5-abf4-544ac2328bbc@intel.com> Date: Thu, 24 Sep 2026 10:05:43 +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 v4 1/4] KVM: TDX: Track configurable CPUID bits allowed by KVM To: "Edgecombe, Rick P" , "binbin.wu@linux.intel.com" Cc: "Gao, Chao" , "seanjc@google.com" , "dave.hansen@linux.intel.com" , "kas@kernel.org" , "Maloor, Kishen" , "linux-kernel@vger.kernel.org" , "tony.lindgren@linux.intel.com" , "kvm@vger.kernel.org" , "pbonzini@redhat.com" , "nik.borisov@suse.com" , "dedekind1@gmail.com" , "andrew.cooper3@citrix.com" References: <20260917072548.2314491-1-binbin.wu@linux.intel.com> <20260917072548.2314491-2-binbin.wu@linux.intel.com> <5ff81fc4-d144-4b2b-8375-d2f63e0dd618@linux.intel.com> <419b23f264af219da3be93a9d246b5401bbbaf13.camel@intel.com> <5168e058946a61f3be1cdb13f886dd632739d312.camel@intel.com> <2cc4bbc3-11d3-48bd-9a9b-a9659fc101a1@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/23/2026 10:25 PM, Edgecombe, Rick P wrote: >> But for TDX, >> there is not interface to report KVM's support capabilities. After this >> series, KVM_TDX_CAPABILITIES can serve as the interface. So it looks like a >> bug fix to me. > KVM needs to support all the bits that are 1 in the TD. Either directly > configurable or fixed-1 or whatever. Userspace doesn't find out which bits these > are until it does the KVM_TDX_GET_CPUID, at which point it finds out the > "support" in a heavy handed way. So I think userspace does learn everything it > needs already. And as long we don't have new fixed-1 bits, we will avoid KVM > being forced to support things too early. Do you mean after this series of before this series? Before this series, i.e. with current KVM, KVM_TDX_GET_CPUID can tell userspace the "support" bit for a given TD, but some of the "support" bits might not be supported by KVM. For example, current userspace can set RDT_A and RDT_M, and they will be reported as 1 on KVM_TDX_GET_CPUID. However, KVM doesn't support them. After this series, KVM will not report such bits like RDT_A and RDT_M any more, and userspace will no longer be able to set them for a TD neither.