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, URIBL_BLOCKED,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 1F34DC2D0E4 for ; Thu, 19 Nov 2020 07:54:34 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 896A1246BB for ; Thu, 19 Nov 2020 07:54:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 896A1246BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 054F087383; Thu, 19 Nov 2020 07:54:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Z2HEeB9Hxq-k; Thu, 19 Nov 2020 07:54:31 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 146138736C; Thu, 19 Nov 2020 07:54:31 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id EC609C163C; Thu, 19 Nov 2020 07:54:30 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 976FCC0891 for ; Thu, 19 Nov 2020 07:54:29 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 9380585C08 for ; Thu, 19 Nov 2020 07:54:29 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BYIAcV8jhELt for ; Thu, 19 Nov 2020 07:54:28 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 0B808859CF for ; Thu, 19 Nov 2020 07:54:27 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 5338667373; Thu, 19 Nov 2020 08:54:23 +0100 (CET) Date: Thu, 19 Nov 2020 08:54:22 +0100 From: Christoph Hellwig To: Ashish Kalra Subject: Re: [PATCH v5] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests. Message-ID: <20201119075422.GA15840@lst.de> References: <20201118201243.18510-1-Ashish.Kalra@amd.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20201118201243.18510-1-Ashish.Kalra@amd.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Thomas.Lendacky@amd.com, jon.grimm@amd.com, brijesh.singh@amd.com, dave.hansen@linux-intel.com, konrad.wilk@oracle.com, peterz@infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, mingo@redhat.com, bp@alien8.de, luto@kernel.org, hpa@zytor.com, rientjes@google.com, tglx@linutronix.de, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, Nov 18, 2020 at 08:12:43PM +0000, Ashish Kalra wrote: > From: Ashish Kalra > > For SEV, all DMA to and from guest has to use shared > (un-encrypted) pages. SEV uses SWIOTLB to make this > happen without requiring changes to device drivers. > However, depending on workload being run, the default > 64MB of SWIOTLB might not be enough and SWIOTLB > may run out of buffers to use for DMA, resulting > in I/O errors and/or performance degradation for > high I/O workloads. FYI, you can use up 73 chars for your commit log. This looks rather compressed. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu