From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.21]) (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 DD16B3783C3; Tue, 29 Sep 2026 00:19:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.21 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790641200; cv=none; b=WfG+GZX67zN+tx0RNg9XFUoxyEmlOvLnEWa2lK+j6Um2gQfzMGA3hSDRSRB4DBFJZgD92a+IPpxndiShG4wBNrcszEMicb+dJImQs0q6Be63owT5x5BZCMb5pKeSzxWqd6u+cor3OOHnmgmZRwjwO9DWFbo41tbzBMMQp6MSolU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790641200; c=relaxed/simple; bh=BwX/BkX3f9mp6+4BYNr1evnobdAgb5wrMhB8WZW8+kA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Wt3TfGisS7G0fQuZzpi6e6iEC2vsW6YAkia5ta3Xn5MxiOJrT0kT2Xxr4+rNRUGwsEUs5FIgEVBkSnqQvJJYvpaJoLadXnk1uWRCoeCmJ4enL2W178ytWe/fyRBNHSVyKbbyOD/sz0VQj9s55SLu5zmKhaN28J94TWN6coPqt8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=MiMYr9TV; arc=none smtp.client-ip=198.175.65.21 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="MiMYr9TV" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1790641195; x=1822177195; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=BwX/BkX3f9mp6+4BYNr1evnobdAgb5wrMhB8WZW8+kA=; b=MiMYr9TVJjcKAl7gB/drQLnVtyVMSIPOS8cqpEXLy3cqp17weVTWDTbs LQNLS3yyriecsRr0FFaHYhzKRDl4vPQDxM6X939EauKTOkb4d9GK5njYq +tmodC/KXaBQcD5k5SuSU//8b9PEJGWTa5eOTq28eiPqAX3qvHOYx/eDq aUAOt/8pnWNjIp0cJxNeUZ+gwaXNKQafAFAkp9Nq7OmGj6JglU3F0+iMk A5bz2OHphutTfS7rBIw/ZEtqO+dKvdaQTiQwux7xev8V78vpL7BOFRYDH X2ubrYXQBTt2TH1kTVWkPX/NfO8l5HK80JWXeeZSIv4t0OQnAbkHHs9ZZ A==; X-CSE-ConnectionGUID: vacoaxpLS6iE3F4MZtuCEw== X-CSE-MsgGUID: 9kKMZqG0SPWi14+rjOlNvA== X-IronPort-AV: E=McAfee;i="6800,10657,11919"; a="90217401" X-IronPort-AV: E=Sophos;i="6.27,129,1787036400"; d="scan'208";a="90217401" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by orvoesa113.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 17:19:50 -0700 X-CSE-ConnectionGUID: loBOEpsSSz+EoBHEJL2QQw== X-CSE-MsgGUID: Q37POYIVSFuGXM6GZHxmYQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,129,1787036400"; d="scan'208";a="275340580" Received: from binbinwu-mobl.ccr.corp.intel.com (HELO [10.124.245.162]) ([10.124.245.162]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2026 17:19:46 -0700 Message-ID: Date: Tue, 29 Sep 2026 08:19:43 +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" , "Li, Xiaoyao" Cc: "Gao, Chao" , "dedekind1@gmail.com" , "seanjc@google.com" , "dave.hansen@linux.intel.com" , "kas@kernel.org" , "linux-kernel@vger.kernel.org" , "Maloor, Kishen" , "tony.lindgren@linux.intel.com" , "andrew.cooper3@citrix.com" , "kvm@vger.kernel.org" , "nik.borisov@suse.com" , "pbonzini@redhat.com" References: <20260917072548.2314491-1-binbin.wu@linux.intel.com> <20260917072548.2314491-2-binbin.wu@linux.intel.com> <39047bbc-757d-4131-a25c-5a7743fd591a@intel.com> <062f5365-7eb5-4e04-9c84-f5ecd566f019@linux.intel.com> <8bcba51e-2a3b-44b8-89cd-aebfd1e50cfd@linux.intel.com> Content-Language: en-US From: Binbin Wu In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/29/2026 7:58 AM, Edgecombe, Rick P wrote: > >> >> My consideration was maybe some userspace could set this bit. >> >> But userspace is expected to consult KVM_TDX_CAPABILITIES for the configurable >> bits before invoking KVM_TDX_INIT_VM > > If a guest is already using it, then even if the bit disappears from > KVM_TDX_CAPABILITIES it could cause a regression when it doesn't get configured > in the guest. The precondition is these excluded features bits are not in kvm_cpu_caps[], i.e. these features are - Obsolete or - Not supported by KVM, there would have been issues if a guest is using them. I will add the precondition when describe it in the change log. > >> , regardless of this patch series, there is no risk to break userspace, except >> for CORE_CAPABILITIES, which is the only >> special case as it was defined as fixed-1. >> >> I think there is no need to add XTPR to the allow list either. >