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=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 5E454C282C3 for ; Thu, 24 Jan 2019 15:00:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A22321872 for ; Thu, 24 Jan 2019 15:00:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728208AbfAXPAC (ORCPT ); Thu, 24 Jan 2019 10:00:02 -0500 Received: from 8bytes.org ([81.169.241.247]:59616 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728203AbfAXPAC (ORCPT ); Thu, 24 Jan 2019 10:00:02 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id 1A641269; Thu, 24 Jan 2019 16:00:00 +0100 (CET) Date: Thu, 24 Jan 2019 16:00:00 +0100 From: Joerg Roedel To: Christoph Hellwig Cc: "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 2/5] swiotlb: Add is_swiotlb_active() function Message-ID: <20190124150000.GN32526@8bytes.org> References: <20190123163049.24863-1-joro@8bytes.org> <20190123163049.24863-3-joro@8bytes.org> <20190123212755.GA9032@lst.de> <20190124082923.GI32526@8bytes.org> <20190124084107.GA19441@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190124084107.GA19441@lst.de> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Jan 24, 2019 at 09:41:07AM +0100, Christoph Hellwig wrote: > On Thu, Jan 24, 2019 at 09:29:23AM +0100, Joerg Roedel wrote: > > > As I've just introduced and fixed a bug in this area in the current > > > cycle - I don't think no_iotlb_memory is what your want (and maybe > > > not useful at all): if the arch valls swiotlb_exit after previously > > > initializing a buffer it won't be set. You probably want to check > > > for non-zero io_tlb_start and/or io_tlb_end. > > > > Okay, but that requires that I also set io_tlb_start and friends back to > > zero in the failure path of swiotlb_init(). Otherwise it could be left > > non-zero in case swiotlb_init_with_tbl() returns an error. > > Indeed, and we'll need to do that anyway as otherwise the dma mapping > path might cause problems similar to the one when swiotlb_exit is > called that I fixed. Turns out the the error path in swiotlb_init() is redundant because it will never be executed. If the function returns it will always return 0 because in case of failure it will just panic (through memblock_alloc). I'll clean that up in a separate patch-set. There are more users of that function and all of them panic when the function fails. Joerg