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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C7300C433EF for ; Tue, 8 Feb 2022 10:51:30 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3062C6B0074; Tue, 8 Feb 2022 05:51:30 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B5256B0075; Tue, 8 Feb 2022 05:51:30 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1A45B6B0078; Tue, 8 Feb 2022 05:51:30 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0103.hostedemail.com [216.40.44.103]) by kanga.kvack.org (Postfix) with ESMTP id 0A9BD6B0074 for ; Tue, 8 Feb 2022 05:51:30 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id BD85593D8B for ; Tue, 8 Feb 2022 10:51:29 +0000 (UTC) X-FDA: 79119296298.13.D76E005 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by imf07.hostedemail.com (Postfix) with ESMTP id 0E40540008 for ; Tue, 8 Feb 2022 10:51:28 +0000 (UTC) Received: from zn.tnic (dslb-088-067-221-104.088.067.pools.vodafone-ip.de [88.67.221.104]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id F0C0A1EC00F8; Tue, 8 Feb 2022 11:51:21 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1644317482; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=yxZ0nR15n7mkZeUUipZpTNufPRwpkzb7/Yfx2nthKHw=; b=T9Uwof1JPVAt8ASYSIUa3QaOxuvcwTqgS4A1/d8dSH3XsLJGSVDgzqkQEA3SpoBzGPKWbN qK1A+0n4DUJlXw9Oy3UzYqF5LJ2Bi/mjDuQKYD5N5jE0WdXS382dpSohbyviT6xPIP402H NxXMNHdzWIPMeDDmQa1BOpu9LiTkpxA= Date: Tue, 8 Feb 2022 11:51:16 +0100 From: Borislav Petkov To: Dov Murik Cc: Brijesh Singh , x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-efi@vger.kernel.org, platform-driver-x86@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Jim Mattson , Andy Lutomirski , Dave Hansen , Sergio Lopez , Peter Gonda , Peter Zijlstra , Srinivas Pandruvada , David Rientjes , Tobin Feldman-Fitzthum , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , "Dr . David Alan Gilbert" , brijesh.ksingh@gmail.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, Liam Merwick Subject: Re: [PATCH v9 42/43] virt: sevguest: Add support to derive key Message-ID: References: <20220128171804.569796-1-brijesh.singh@amd.com> <20220128171804.569796-43-brijesh.singh@amd.com> <1cb4fdf5-7c1e-6c8f-1db6-8c976d6437c2@amd.com> <20ba1ac2-83d1-6766-7821-c9c8184fb59b@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=alien8.de header.s=dkim header.b=T9Uwof1J; dmarc=pass (policy=none) header.from=alien8.de; spf=pass (imf07.hostedemail.com: domain of bp@alien8.de designates 5.9.137.197 as permitted sender) smtp.mailfrom=bp@alien8.de X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0E40540008 X-Stat-Signature: ruuce1dc79eankyz8dg4jqez85erbymg X-HE-Tag: 1644317488-685412 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Feb 08, 2022 at 09:56:52AM +0200, Dov Murik wrote: > Just to be clear, I didn't mean necessarily "leak the key to the > untrusted host" (even if a page is converted back from private to > shared, it is encrypted, so host can't read its contents). But even > *inside* the guest, when dealing with sensitive data like keys, we > should minimize the amount of copies that float around (I assume this is > the reason for most of the uses of memzero_explicit() in the kernel). I don't know about Brijesh but I understood you exactly as you mean it. And yap, I agree we should always clear such sensitive buffers. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette