From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 865B3C433F5 for ; Thu, 21 Apr 2022 14:53:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1389550AbiDUO4l (ORCPT ); Thu, 21 Apr 2022 10:56:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244846AbiDUO4l (ORCPT ); Thu, 21 Apr 2022 10:56:41 -0400 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9C6F265F2; Thu, 21 Apr 2022 07:53:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650552831; x=1682088831; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=Q334Y3bRjAYyNyCQa2C9eINciS6WLB37pPfz+kWVNHo=; b=b1CCgIxvMs2VCkD+bzfH3ZrydR91lzq7x1sGdje83uRyvrc4Q3XVZGt1 SZL/d3XJnV3nO641++RfF5+M5LX44nqvyWqL0Vky46QcbfNth0GAiDcon DmQF2u/OHTKF97UZqElSTDuAoEhAEhHgDYRvIVaXfENmEAhwfW+3y7uMz drJB8FzEg/lFb84o8L5tKGKjTCOIHVBzE9/Cr7uoA6dUCDK08O9aUHo07 2IfIwE2QAiYHAtBgJnECoiRrzwEqvjn6eqj2ZScCOwBV0eFbwiHo8XQEr fJEd/5iMKD1N6kzO75Fb4S47KJwEBn474Gi3M9K59/KkrLG5YL8KaLktH A==; X-IronPort-AV: E=McAfee;i="6400,9594,10324"; a="350810848" X-IronPort-AV: E=Sophos;i="5.90,279,1643702400"; d="scan'208";a="350810848" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Apr 2022 07:53:41 -0700 X-IronPort-AV: E=Sophos;i="5.90,279,1643702400"; d="scan'208";a="511098190" Received: from testes-mobl1.amr.corp.intel.com (HELO [10.212.210.35]) ([10.212.210.35]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Apr 2022 07:53:40 -0700 Message-ID: Date: Thu, 21 Apr 2022 07:53:39 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Firefox/91.0 Thunderbird/91.7.0 Subject: Re: [PATCH v3 4/4] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Content-Language: en-US To: Isaku Yamahata Cc: Kai Huang , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Hans de Goede , Mark Gross , "H . Peter Anvin" , "Kirill A . Shutemov" , Tony Luck , Andi Kleen , linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org References: <20220415220109.282834-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20220415220109.282834-5-sathyanarayanan.kuppuswamy@linux.intel.com> <420a4d689f73f9f7dc1ef71c61da75b7c9777a3f.camel@intel.com> <1e184b44-8024-b8ae-98a8-cf2b6f78df61@linux.intel.com> <20220421065707.GA1423762@private.email.ne.jp> From: Sathyanarayanan Kuppuswamy In-Reply-To: <20220421065707.GA1423762@private.email.ne.jp> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: platform-driver-x86@vger.kernel.org On 4/20/22 11:57 PM, Isaku Yamahata wrote: > On Wed, Apr 20, 2022 at 07:42:06PM -0700, > Sathyanarayanan Kuppuswamy wrote: > >> >> >> On 4/20/22 5:11 PM, Kai Huang wrote: >>> On Wed, 2022-04-20 at 16:45 -0700, Sathyanarayanan Kuppuswamy wrote: >>>> If we want to support multiple GetQuote requests in parallel, then we >>>> need some way to uniquely identify the GetQuote requests. So that when >>>> we get completion notification, we can understand which request is >>>> completed. This part is not mentioned/discussed in ABI spec. So we want >>>> to serialize the requests for now. >>>> >>> >>> Yes it's unfortunate that this part (whether concurrent GetQuote requests are >>> supported by TDX architecture) is not explicitly mentioned in GHCI spec. I am >>> fine with only supporting GetQuote requests one by one. AFAICT there's no >>> request to support concurrent GetQuote requests anyway. What concerns me is >>> exactly how explain this. >>> >>> As I said, we have GET_QUOTE_IN_FLIGHT flag now. Theoretically, you can queue >>> multiple GetQuote requests, and when you receive the interrupt, you check which >>> buffer has GET_QUOTE_IN_FLIGHT cleared. That buffer is the one with Quote >>> ready. However I am not 100% sure whether above will always work. Interrupt >>> can get lost when there are multiple Quotes ready in multiple buffer in very >>> short time period, etc? Perhaps Isaku can provide more input here. >> >> Either supported or not, it should be mentioned in the GHCI spec. Currently, >> there are no details related to it. If it is supported, the specification >> should include the protocol to use. >> >> I will check with Isaku about it. > > The spec says that TD can call multiple GetQuote requests in parallel. Sorry, I missed the above content. Thanks for pointing out. > > TDG.VP.VMCALL API allows one TD to issue multiple requests. It's > implementation specific that how many concurrent requests are allowed. The TD > should be able to handle TDG.VP.VMCALL_RETRY if it chooses to issue multiple > requests simultaneously Do you know why we should handle VMCALL_RETRY case? IIUC, as per above spec, if each request we send uses different GPA buffer, then we should not even worry about checking for IN_FLIGHT status. right? > > As Kai said, there is no requirement for multiple GetQuote in parallel, it's > okay to support only single request at the same time. For now I will leave it as single request at a time. > > While the status is GET_QUOTE_IN_FLIGHT, VMM owns the shared GPA. The > attestation driver should wait for GET_QUOTE_IN_FLIGHT to be cleared before > sending next request. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer