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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 BAA0BC49ED7 for ; Fri, 20 Sep 2019 09:37:24 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 93D992086A for ; Fri, 20 Sep 2019 09:37:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 93D992086A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57158 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBFLv-0006vA-C6 for qemu-devel@archiver.kernel.org; Fri, 20 Sep 2019 05:37:23 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53006) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iBFDS-0005Ax-GY for qemu-devel@nongnu.org; Fri, 20 Sep 2019 05:28:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iBFDR-0008Hx-Dz for qemu-devel@nongnu.org; Fri, 20 Sep 2019 05:28:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43006) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iBFDR-0008Hb-9k for qemu-devel@nongnu.org; Fri, 20 Sep 2019 05:28:37 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6B05E641C7; Fri, 20 Sep 2019 09:28:36 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-120-165.rdu2.redhat.com [10.10.120.165]) by smtp.corp.redhat.com (Postfix) with ESMTP id 83B0F60C80; Fri, 20 Sep 2019 09:28:23 +0000 (UTC) Subject: Re: [edk2-devel] [Qemu-devel] [PATCH 1/2] q35: implement 128K SMRAM at default SMBASE address To: Igor Mammedov References: <20190917130708.10281-1-imammedo@redhat.com> <20190917130708.10281-2-imammedo@redhat.com> <561f4440-7c06-10d7-80ce-bbfa810fec59@redhat.com> <20190920102855.3fe2b689@redhat.com> From: Laszlo Ersek Message-ID: Date: Fri, 20 Sep 2019 11:28:22 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20190920102855.3fe2b689@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Fri, 20 Sep 2019 09:28:36 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: yingwen.chen@intel.com, Brijesh Singh , devel@edk2.groups.io, phillip.goerl@oracle.com, qemu-devel@nongnu.org, alex.williamson@redhat.com, jiewen.yao@intel.com, jun.nakajima@intel.com, michael.d.kinney@intel.com, pbonzini@redhat.com, boris.ostrovsky@oracle.com, rfc@edk2.groups.io, joao.m.martins@oracle.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 09/20/19 10:28, Igor Mammedov wrote: > On Thu, 19 Sep 2019 19:02:07 +0200 > "Laszlo Ersek" wrote: > >> Hi Igor, >> >> (+Brijesh) >> >> long-ish pondering ahead, with a question at the end. > [...] > >> Finally: can you please remind me why we lock down 128KB (32 pages) at >> 0x3_0000, and not just half of that? What do we need the range at >> [0x4_0000..0x4_FFFF] for? > > > If I recall correctly, CPU consumes 64K of save/restore area. > The rest 64K are temporary RAM for using in SMI relocation handler, > if it's possible to get away without it then we can drop it and > lock only 64K required for CPU state. It won't help with SEV > conflict though as it's in the first 64K. OK. Let's go with 128KB for now. Shrinking the area is always easier than growing it. > On QEMU side, we can drop black-hole approach and allocate > dedicated SMRAM region, which explicitly gets mapped into > RAM address space and after SMI hanlder initialization, gets > unmapped (locked). So that SMRAM would be accessible only > from SMM context. That way RAM at 0x30000 could be used as > normal when SMRAM is unmapped. I prefer the black-hole approach, introduced in your current patch series, if it can work. Way less opportunity for confusion. I've started work on the counterpart OVMF patches; I'll report back. Thanks Laszlo