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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 F3C28C282C3 for ; Thu, 24 Jan 2019 08:42:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF04121872 for ; Thu, 24 Jan 2019 08:42:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727388AbfAXImY (ORCPT ); Thu, 24 Jan 2019 03:42:24 -0500 Received: from verein.lst.de ([213.95.11.211]:47436 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725939AbfAXImX (ORCPT ); Thu, 24 Jan 2019 03:42:23 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id 059B468DD3; Thu, 24 Jan 2019 09:42:22 +0100 (CET) Date: Thu, 24 Jan 2019 09:42:21 +0100 From: Christoph Hellwig To: Joerg Roedel Cc: Christoph Hellwig , "Michael S . Tsirkin" , Jason Wang , Konrad Rzeszutek Wilk , Jens Axboe , virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jfehlig@suse.com, jon.grimm@amd.com, brijesh.singh@amd.com, jroedel@suse.de Subject: Re: [PATCH 5/5] virtio-blk: Consider virtio_max_dma_size() for maximum segment size Message-ID: <20190124084221.GB19441@lst.de> References: <20190123163049.24863-1-joro@8bytes.org> <20190123163049.24863-6-joro@8bytes.org> <20190123213139.GD9032@lst.de> <20190124084011.GJ32526@8bytes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190124084011.GJ32526@8bytes.org> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 24, 2019 at 09:40:11AM +0100, Joerg Roedel wrote: > > I wonder if we should just move the dma max segment size check > > into blk_queue_max_segment_size so that all block drivers benefit > > from it. Even if not I think at least the SCSI midlayer should > > be updated to support it. > > In that case the limit would also apply to virtio-blk even if it doesn't > use the DMA-API. If that is acceptable we can move the check to > blk_queue_max_segment_size(). Yes. But more importantly it would fix the limit for all other block drivers that set large segment sizes when running over swiotlb.