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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07B34C433F5 for ; Sun, 5 Dec 2021 12:48:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233817AbhLEMwA (ORCPT ); Sun, 5 Dec 2021 07:52:00 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:44946 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233720AbhLEMv7 (ORCPT ); Sun, 5 Dec 2021 07:51:59 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id A3B96B80E3F for ; Sun, 5 Dec 2021 12:48:31 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDC66C341C1; Sun, 5 Dec 2021 12:48:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638708510; bh=/imDibze4+Ir42NwsjTzw/XZJFZq7yjaSO2qKrwHYZk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TY7PiGfHLEfU8tWBTdrnGSzNRcAwOuNPK4YJAx+4HVOwY9eNiqVWR8gj20ka7bK1G rUTzcxSxYiFpqacMSatT3xDo///SNBG6fD4zhgobOe9w6Im94MeoQe+O8p26+Slzjm AM87YVELEerw62xYqMfsH54EZLf4mi4qsnpqCeoc= Date: Sun, 5 Dec 2021 13:48:18 +0100 From: Greg Kroah-Hartman To: Hans de Goede Cc: Mathias Nyman , Pavankumar Kondeti , linux-usb Subject: Re: Regression: "xhci: Fix command ring pointer corruption while aborting a command" breaks USB on Intel controllers Message-ID: References: <0a4d723c-221f-a42a-434c-34283a4cdab7@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sun, Dec 05, 2021 at 09:20:00AM +0100, Greg Kroah-Hartman wrote: > On Sat, Dec 04, 2021 at 03:15:15PM +0100, Hans de Goede wrote: > > Hi All, > > > > There are several bug reports (arch and Fedora) about USB problems > > starting with kernel 5.14.14 (5.14.13 is ok): > > > > https://bugzilla.redhat.com/show_bug.cgi?id=2019788 > > https://bbs.archlinux.org/viewtopic.php?pid=2006862 > > > > And 5.16.6, which has the hub address0_mutex fixes does not > > fix these problems for some users. > > > > Looking at the history between those 2 commit ff0e50d3564f > > ("xhci: Fix command ring pointer corruption while aborting a command"): > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ff0e50d3564f > > > > stood out to me as a possible cause of this. So I've build > > a test 5.15.6 kernel for Fedora users with that commit reverted > > and 2 users have now reported that this fixes things for them > > (see https://bugzilla.redhat.com/show_bug.cgi?id=2019788). > > > > The reason why this stood out to me is because doing a 32 bit > > write over a possibly 64 bit databus to the xHCI controller may > > result in the hw doing a 64 bit read + modify 32 bit + 64 bit write, > > so I think that the following is happening after the commit: > > > > sw: read 32 bit > > hw: read 64 bit, return 32 bit > > sw: modify it > > sw: write 32 bit > > hw: read 64 bit > > hw: modify 32 bit of 64 bit wor5d > > hw: write 64 bit > > > > Which actually makes the chances of hitting the problem the commit > > tries to fix larger on controllers using a 64 bit data bus. > > > > Note this is just a theory, but it seems plausible to me. > > > > All problem reports are people using integrated Intel xHCI controllers > > which I believe are likely to use a 64 bit data-bus. > > I think this is fixed by 09f736aa9547 ("xhci: Fix commad ring abort, > write all 64 bits to CRCR register.") in linux-next and I'll be sending > it to Linus in a few hours. Pull request is here: https://lore.kernel.org/r/Yayq/Xdb/pHSS7/l@kroah.com