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 45F4FC43381 for ; Thu, 28 Feb 2019 12:19:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1EA30214D8 for ; Thu, 28 Feb 2019 12:19:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731126AbfB1MTx (ORCPT ); Thu, 28 Feb 2019 07:19:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35896 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726066AbfB1MTx (ORCPT ); Thu, 28 Feb 2019 07:19:53 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 46C4112E517; Thu, 28 Feb 2019 12:19:53 +0000 (UTC) Received: from localhost (unknown [10.43.2.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id BECC618379; Thu, 28 Feb 2019 12:19:50 +0000 (UTC) Date: Thu, 28 Feb 2019 13:19:48 +0100 From: Stanislaw Gruszka To: Joerg Roedel Cc: Lorenzo Bianconi , Rosen Penev , linux-wireless , Samuel Sieb , Alexander Duyck , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: MT76x2U crashes XHCI driver on AMD Ryzen system Message-ID: <20190228121948.GD6072@redhat.com> References: <20190114091841.GA23045@localhost.localdomain> <20190115090400.GA2267@localhost.localdomain> <20190218143742.GA11872@redhat.com> <20190226100535.GA20740@8bytes.org> <20190226103450.GA2989@redhat.com> <20190226104413.GH20740@8bytes.org> <20190226112407.GB2989@redhat.com> <20190228090411.GA24938@redhat.com> <20190228104223.GA2749@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190228104223.GA2749@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Thu, 28 Feb 2019 12:19:53 +0000 (UTC) Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org On Thu, Feb 28, 2019 at 11:42:24AM +0100, Stanislaw Gruszka wrote: > On Thu, Feb 28, 2019 at 10:04:12AM +0100, Stanislaw Gruszka wrote: > > On Tue, Feb 26, 2019 at 12:24:08PM +0100, Stanislaw Gruszka wrote: > > > On Tue, Feb 26, 2019 at 11:44:13AM +0100, Joerg Roedel wrote: > > > > On Tue, Feb 26, 2019 at 11:34:51AM +0100, Stanislaw Gruszka wrote: > > > > > On Tue, Feb 26, 2019 at 11:05:36AM +0100, Joerg Roedel wrote: > > > > > If sg->offset > PAGE_SIZE is fine then most likely we have problem with > > > > > alignment. > > > > > > > > The map_sg implementation in the AMD IOMMU driver uses sg_phys() which > > > > handles the sg->page + sg->offset calculation fine. > > > > > > > > > Note hat issue is with dma_map_sg(), switching to dma_map_single() > > > > > by using urb->transfer_buffer instead of urb->sg make things work > > > > > on AMD IOMMU. > > > > > > > > On the other hand this points to a bug in the driver, I'll look further > > > > if I can spot something there. > > > > > > I think so too. And I have done some changes that avoid strange allocation > > > scheme and use usb synchronous messages instead of allocating buffers > > > with unaligned sizes. However things work ok on Intel IOMMU and > > > there is no documentation what are dma_map_sg() requirement versus > > > dma_map_single() which works. I think there are some unwritten > > > requirements and things can work on some platforms and fails on others > > > (different IOMMUs, no-IOMMU on some ARCHes) > > > > For the record: we have another bug report with this issue: > > https://bugzilla.kernel.org/show_bug.cgi?id=202673 > > > > I provided there patch that change alignment for page_frag_alloc() and > > it did not fixed the problem. So this is not alignment issue. > > Now I think it could be page->refcount issue ... > > I looked at the map_sg() in amd_iommu.c code and one line looks suspicious > to me, seems we can use not correctly initialized s->dma_address (should be 0, > but I think can be non-zero if SG was reused). The code also seems do > not do correct thing if there is more than one SG with multiple pages > on individual segments. Something like in below patch seems to be more > appropriate to me (not tested nor compiled). Nevermind, the patch is wrong, s->dma_address is initalized in sg_num_pages(). Stanislaw