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 X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F0120C4321D for ; Fri, 24 Aug 2018 15:50:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A97512152B for ; Fri, 24 Aug 2018 15:50:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A97512152B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727360AbeHXTZe (ORCPT ); Fri, 24 Aug 2018 15:25:34 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:35368 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726268AbeHXTZe (ORCPT ); Fri, 24 Aug 2018 15:25:34 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4B0547A7E7; Fri, 24 Aug 2018 15:50:20 +0000 (UTC) Received: from [10.36.116.27] (ovpn-116-27.ams2.redhat.com [10.36.116.27]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 89D8316878; Fri, 24 Aug 2018 15:50:17 +0000 (UTC) Subject: Re: SEV guest regression in 4.18 To: Brijesh Singh , Sean Christopherson Cc: Borislav Petkov , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "Lendacky, Thomas" , Thomas Gleixner References: <20ad6cd5-394c-d3ae-d99c-b656d7ef8293@amd.com> <20180821083911.GF24940@nazgul.tnic> <3d46f44c-dd78-8fa9-02ac-8206676ffde9@amd.com> <20180821151938.GA31212@nazgul.tnic> <92e2b80c-0dcc-94be-8d3a-5e11e5cf2370@amd.com> <20180822081417.GB4069@nazgul.tnic> <20180822150033.GA14200@linux.intel.com> <4d6ee892-a34f-28b3-18b7-1c663eb281c6@amd.com> <9635ebf0-7c99-6edf-1240-8dec28036a70@redhat.com> <20180823152907.GA1488@linux.intel.com> <60acb594-abe3-912f-9702-2f34961e575d@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; 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Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 24 Aug 2018 15:50:20 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Fri, 24 Aug 2018 15:50:20 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'pbonzini@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/08/2018 17:41, Brijesh Singh wrote: >>> >>> Wouldn't that result in exposing/leaking whatever code/data happened >>> to reside on the same 2M page (or corrupting it if the entire page >>> isn't decrypted)?  Or are you suggesting that we'd also leave the >>> encrypted mapping intact? >> >> Yes, exactly the latter, because... > > > Hardware does not enforce coherency between the encrypted and > unencrypted mapping for the same physical page. So, creating a > two mapping of same physical address will lead a possible data > corruption. > > Note, SME creates two mapping of the same physical address to perform > in-place encryption of kernel and initrd images; this is a special case > and APM documents steps on how to do this. Ah, so that's what I was thinking about. But a single cache line would never be used both encrypted and unencrypted, would it? Paolo