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 C75BFC433EF for ; Mon, 25 Apr 2022 03:06:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240541AbiDYDJY (ORCPT ); Sun, 24 Apr 2022 23:09:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35434 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240533AbiDYDJW (ORCPT ); Sun, 24 Apr 2022 23:09:22 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87F971A804; Sun, 24 Apr 2022 20:06:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1650855978; x=1682391978; h=subject:to:cc:references:from:message-id:date: mime-version:in-reply-to:content-transfer-encoding; bh=wzcfAC4EW6C554hMgwZb2AgCiWDyJSnxxuhCNsH2j+w=; b=j0fbmQbxQPdk/SJKW32asnhbyxQCQz2EZs25aNwMJjw3yr2+DLEVk56o q9FSIMWvi7gVIcCD9Py+wB0Oies/G/8KdYIbPjWB2tz1E9sykF+ZAi+// 53M9e4SKZGrx9ZXQuFSxDd3wADDtCSvmczF6aFwmMyVFhkEtrpnkPq6km B0rWsLfGyQVVg3dplm41kl3grQVXVF0kHPc9+SX6FztvYvC6kWbkCrWxy 3s8JEUprD+uWF3mOTwpo9ti4EdmWuR/HD8rfEXeGV5dTq3TReoj4pHpFg aShJt0skj/Q7K+Lxu5MGBDrPMRGf3NOjaFJMmGCIyduBR1wTHBJLUtdop Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10327"; a="264918601" X-IronPort-AV: E=Sophos;i="5.90,287,1643702400"; d="scan'208";a="264918601" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Apr 2022 20:06:17 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.90,287,1643702400"; d="scan'208";a="676148747" Received: from aubrey-app.sh.intel.com (HELO [10.239.53.25]) ([10.239.53.25]) by orsmga004.jf.intel.com with ESMTP; 24 Apr 2022 20:06:14 -0700 Subject: Re: [PATCH v3 2/4] x86/tdx: Add tdx_hcall_get_quote() API support To: Isaku Yamahata , Sathyanarayanan Kuppuswamy Cc: 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> <20220415220109.282834-3-sathyanarayanan.kuppuswamy@linux.intel.com> <9a72ac4d-bb39-0459-7989-2bd65db1a2c2@linux.intel.com> <20220422172422.GA2913259@ls.amr.corp.intel.com> From: Aubrey Li Message-ID: <485ad342-3752-0697-802c-f128de0061be@linux.intel.com> Date: Mon, 25 Apr 2022 11:06:15 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20220422172422.GA2913259@ls.amr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/4/23 上午1:24, Isaku Yamahata wrote: > On Wed, Apr 20, 2022 at 12:16:04AM -0700, > Sathyanarayanan Kuppuswamy wrote: > >> >> >> On 4/19/22 8:39 PM, Aubrey Li wrote: >>> On 2022/4/16 上午6:01, Kuppuswamy Sathyanarayanan wrote: >>>> Attestation is the process used by two un-trusted entities to prove to >>>> each other that it can be trusted. In TDX guest, attestation is mainly >>>> used to verify the trustworthiness of a TD to the 3rd party key >>>> servers. >>>> >>>> First step in the attestation process is to generate the TDREPORT data. >>>> This support is added using tdx_mcall_tdreport() API. The second stage >>>> in the attestation process is for the guest to request the VMM generate >>>> and sign a quote based on the TDREPORT acquired earlier. More details >>>> about the steps involved in attestation process can be found in TDX >>>> Guest-Host Communication Interface (GHCI) for Intel TDX 1.5, section >>>> titled "TD attestation" >>>> >>>> Add tdx_hcall_get_quote() helper function to implement the GetQuote >>>> hypercall. >>>> >>>> More details about the GetQuote TDVMCALL are in the Guest-Host >>>> Communication Interface (GHCI) Specification, sec 3.3, titled >>>> "VP.VMCALL". >>>> >>>> This will be used by the TD attestation driver in follow-on patches. >>>> >>>> Reviewed-by: Tony Luck >>>> Reviewed-by: Andi Kleen >>>> Acked-by: Kirill A. Shutemov >>>> Signed-off-by: Kuppuswamy Sathyanarayanan >>>> --- >>>> arch/x86/coco/tdx/tdx.c | 38 ++++++++++++++++++++++++++++++++++++++ >>>> arch/x86/include/asm/tdx.h | 2 ++ >>>> 2 files changed, 40 insertions(+) >>>> >>>> diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c >>>> index 3e409b618d3f..c259d81a5d7f 100644 >>>> --- a/arch/x86/coco/tdx/tdx.c >>>> +++ b/arch/x86/coco/tdx/tdx.c >>>> @@ -21,6 +21,7 @@ >>>> /* TDX hypercall Leaf IDs */ >>>> #define TDVMCALL_MAP_GPA 0x10001 >>>> +#define TDVMCALL_GET_QUOTE 0x10002 >>>> /* MMIO direction */ >>>> #define EPT_READ 0 >>>> @@ -144,6 +145,43 @@ long tdx_mcall_tdreport(void *data, void *reportdata) >>>> } >>>> EXPORT_SYMBOL_GPL(tdx_mcall_tdreport); >>>> +/* >>>> + * tdx_hcall_get_quote() - Generate TDQUOTE using TDREPORT_STRUCT. >>>> + * >>>> + * @data : Address of 8KB GPA memory which contains >>>> + * TDREPORT_STRUCT. >>>> + * @len : Length of the GPA in bytes. >>>> + * >>>> + * return 0 on success or failure error number. >>>> + */ >>>> +long tdx_hcall_get_quote(void *data, u64 len) >>>> +{ >>>> + u64 ret; >>>> + >>>> + /* >>>> + * Use confidential guest TDX check to ensure this API is only >>>> + * used by TDX guest platforms. >>>> + */ >>>> + if (!data || !cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) >>>> + return -EINVAL; >>>> + >>>> + /* >>>> + * Pass the physical address of tdreport data to the VMM >>>> + * and trigger the tdquote generation. Quote data will be >>>> + * stored back in the same physical address space. More info >>>> + * about ABI can be found in TDX Guest-Host-Communication >>>> + * Interface (GHCI), sec titled "TDG.VP.VMCALL". >>>> + */ >>>> + ret = _tdx_hypercall(TDVMCALL_GET_QUOTE, cc_mkdec(virt_to_phys(data)), >>>> + len, 0, 0); >>>> + >>> >>> I commented here in v2 but no response, so let me try again. >>> >>> IIUC, virt_to_phys(data) (GPA) will be stored in the register when >>> TDCALL brings the context back to the VMX root mode, and hypervisor(QEMU) >>> will find the mapped host virtual address(HVA) with the GPA in the register, >>> and the subsequent ops will be HVA<->HVA in hypervisor, EPT will not be >>> involved so no need to cc_mkdec() this GPA. >>> >>> Please help to correct me if I was wrong. >> >> It was done to meet the expectation from VMM. For shared GPA address, >> VMM expects shared bit set. All cc_mkdec() does is to set this bit. > > This is to conform to the guest-host communicate interface(GHCI) spec. > The input value is defined as "shared GPA as input". Shared GPA is GPA with > shared bit set. > > table TDG.VP.VMCALL - Input Operands > R12 Shared GPA as input – the memory contains a TDREPORT_STRUCT. > The same buffer is used as output – the memory contains a TD Quote. > > > Userspace VMM(qemu) can be implemented to accept GPA with shared bit set or not. > It's not a big issue. > OK, I checked other TDCALL like TDG.VP.VMCALL, the GPA parameter also has shared bit set. So the behavior is consistent. Thanks for the explanation. -Aubrey