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[23.128.96.18]) by mx.google.com with ESMTP id l13si18129158ilh.147.2021.07.12.17.45.59; Mon, 12 Jul 2021 17:46:24 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233792AbhGMArW (ORCPT + 99 others); Mon, 12 Jul 2021 20:47:22 -0400 Received: from mga03.intel.com ([134.134.136.65]:31965 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233517AbhGMArV (ORCPT ); Mon, 12 Jul 2021 20:47:21 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10043"; a="210119400" X-IronPort-AV: E=Sophos;i="5.84,235,1620716400"; d="scan'208";a="210119400" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2021 17:44:26 -0700 X-IronPort-AV: E=Sophos;i="5.84,235,1620716400"; d="scan'208";a="649090900" Received: from kpurma-mobl.amr.corp.intel.com (HELO [10.212.163.17]) ([10.212.163.17]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2021 17:44:23 -0700 Subject: Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver To: "Kuppuswamy, Sathyanarayanan" , Andi Kleen , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Peter Zijlstra , Hans de Goede , Mark Gross , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko Cc: Peter H Anvin , Tony Luck , Dan Williams , Kirill Shutemov , Sean Christopherson , Kuppuswamy Sathyanarayanan , x86@kernel.org, linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, bpf@vger.kernel.org, netdev@vger.kernel.org References: <20210707204249.3046665-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210707204249.3046665-6-sathyanarayanan.kuppuswamy@linux.intel.com> <06c85c19-e16c-3121-ed47-075cfa779b67@kernel.org> <169451ef-e8f6-5a07-f47a-61eaa085b4ef@intel.com> From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: 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 7/12/21 5:33 PM, Kuppuswamy, Sathyanarayanan wrote: > On 7/8/21 5:38 PM, Andi Kleen wrote: >>> Expensive and permanently fractures the direct map. >>> >>> I'm struggling to figure out why the direct map is even touched >>> here. >> I think Sathya did it this way because the TD interface requires a >> physical address. >>> Why not just use a vmalloc area mapping? You really just need >>> *a* decrypted mapping to the page. You don't need to make >>> *every* mapping to the page decrypted. >> >> Yes it would be possible to use vmap() on the page and only set >> the vmap encrypted by passing the right flags directly. > > Is it alright to have non coherent mappings? If yes, any > documentation reference for it? Do you mean non-cache-coherent mappings? I'm not sure what that has to do with creating "unencrypted" (shared) mappings. Are you asking exactly which arguments to pass to vmap() or to vmap_pfn()?