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=-5.2 required=3.0 tests=BAYES_00, 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 0FE52C388F2 for ; Fri, 6 Nov 2020 18:24:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9900208FE for ; Fri, 6 Nov 2020 18:24:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727918AbgKFSY3 (ORCPT ); Fri, 6 Nov 2020 13:24:29 -0500 Received: from verein.lst.de ([213.95.11.211]:52626 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727872AbgKFSY3 (ORCPT ); Fri, 6 Nov 2020 13:24:29 -0500 Received: by verein.lst.de (Postfix, from userid 2407) id 9DA7368B02; Fri, 6 Nov 2020 19:24:24 +0100 (CET) Date: Fri, 6 Nov 2020 19:24:24 +0100 From: Christoph Hellwig To: Konrad Rzeszutek Wilk Cc: Ashish Kalra , hch@lst.de, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, luto@kernel.org, peterz@infradead.org, dave.hansen@linux-intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, brijesh.singh@amd.com, Thomas.Lendacky@amd.com, ssg.sos.patches@amd.com Subject: Re: [PATCH v3] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests. Message-ID: <20201106182424.GA9330@lst.de> References: <20201104220804.21026-1-Ashish.Kalra@amd.com> <20201104221452.GA26079@char.us.oracle.com> <20201104223913.GA25311@ashkalra_ubuntu_server> <20201105174317.GA4294@char.us.oracle.com> <20201105184115.GA25261@ashkalra_ubuntu_server> <20201105190649.GB5366@char.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201105190649.GB5366@char.us.oracle.com> User-Agent: Mutt/1.5.17 (2007-11-01) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 05, 2020 at 02:06:49PM -0500, Konrad Rzeszutek Wilk wrote: > . > > > Right, so I am wondering if we can do this better. > > > > > > That is you are never going to get any 32-bit devices with SEV right? That > > > is there is nothing that bounds you to always use the memory below 4GB? > > > > > > > We do support 32-bit PCIe passthrough devices with SEV. > > Ewww.. Which devices would this be? There is still some new broken shit like that that keeps appearing. GPU is pretty famouts for supporting less than 64-bit addressing, even if it isn't all the way down to 32-bit.