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[23.128.96.18]) by mx.google.com with ESMTP id b17si4511090edu.431.2021.07.08.15.39.21; Thu, 08 Jul 2021 15:39:44 -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 S230388AbhGHWiN (ORCPT + 99 others); Thu, 8 Jul 2021 18:38:13 -0400 Received: from mga05.intel.com ([192.55.52.43]:19171 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229497AbhGHWiN (ORCPT ); Thu, 8 Jul 2021 18:38:13 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10039"; a="295248108" X-IronPort-AV: E=Sophos;i="5.84,225,1620716400"; d="scan'208";a="295248108" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2021 15:35:26 -0700 X-IronPort-AV: E=Sophos;i="5.84,225,1620716400"; d="scan'208";a="646108012" Received: from kezheong-mobl.gar.corp.intel.com (HELO [10.212.152.178]) ([10.212.152.178]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2021 15:35:25 -0700 Subject: Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver To: Andy Lutomirski , Kuppuswamy Sathyanarayanan , 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 , Andi Kleen , 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> 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: <06c85c19-e16c-3121-ed47-075cfa779b67@kernel.org> 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 7/8/21 3:21 PM, Andy Lutomirski wrote: >> + ret = set_memory_decrypted((unsigned long)file->private_data, >> + 1UL << get_order(QUOTE_SIZE)); >> + if (ret) >> + break; > Now private_data is decrypted. (And this operation is *expensive*. Why > is it done at ioctl time?) Expensive and permanently fractures the direct map. I'm struggling to figure out why the direct map is even touched here. 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.