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 30FA7C433EF for ; Sun, 5 Dec 2021 08:20:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232279AbhLEIYJ (ORCPT ); Sun, 5 Dec 2021 03:24:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232292AbhLEIYI (ORCPT ); Sun, 5 Dec 2021 03:24:08 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 407A9C061751 for ; Sun, 5 Dec 2021 00:20:41 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id CE59F60AD3 for ; Sun, 5 Dec 2021 08:20:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8409DC341C1; Sun, 5 Dec 2021 08:20:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1638692440; bh=iqzD/gY69nd+o8dPTjt/1u2nLN6g5BniUv04ICgJODU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=z4l4ywpzhC9RsIvABLniCNAPkmuu5bS5kIfct4E/ckcnGQQ3S6leduFNamqg8SMix 9KUQOQ3ypn1hfJ0aOa+pgeegSuxFY0BCtY/30HXEwLljoAPBQsdeaqD/l/DiQIfdUQ 9MFeim/kkvRHQ9p+m4Uaecu8lrPymtIlEJR7AJLA= Date: Sun, 5 Dec 2021 09:20:36 +0100 From: Greg Kroah-Hartman To: Thorsten Leemhuis Cc: Hans de Goede , 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> <3a5e7a4d-9986-9862-b601-cd7e8bd06855@leemhuis.info> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3a5e7a4d-9986-9862-b601-cd7e8bd06855@leemhuis.info> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sun, Dec 05, 2021 at 07:46:39AM +0100, Thorsten Leemhuis wrote: > Hi, this is your Linux kernel regression tracker speaking. > > On 04.12.21 15:15, 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. > > FWIW, the commit is known to cause problems, one of them is found here: > > https://lore.kernel.org/lkml/35f7428b39f996c793f5b4a6a314772681c73d7a.camel@apache.org/ > > This commit should improve the situation (and afaics hopefully fix all > problems related to it): > > https://lore.kernel.org/stable/20211126122340.1193239-2-mathias.nyman@linux.intel.com/ > > Greg wants to sent it upstream today: > > https://lore.kernel.org/lkml/YatGfEzzniH%2FSrn4@kroah.com/ > > Guess he soon after will backport it to the stable trees as well. > > HTH, Ciao, Thorsten > > #regzbot ^backmonitor > https://lore.kernel.org/lkml/35f7428b39f996c793f5b4a6a314772681c73d7a.camel@apache.org/ Ah, I should have read the whole thread, yes, this should be the fix for this. thanks, greg k-h