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 gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 73EF6C7618D for ; Mon, 20 Mar 2023 13:28:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E792510E03B; Mon, 20 Mar 2023 13:28:11 +0000 (UTC) Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by gabe.freedesktop.org (Postfix) with ESMTPS id D375B10E03B for ; Mon, 20 Mar 2023 13:28:09 +0000 (UTC) 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 26F22614F0; Mon, 20 Mar 2023 13:28:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64EF4C4339C; Mon, 20 Mar 2023 13:28:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1679318889; bh=+4hfR7FRnWoFkcY5muup1dYEccZSPx9x35eXcItS+kE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=K8FaPs4wClF5CAKIi8KriQHi/KRlajW//XNMPdJivW+sdFbkXB3/z2TwPiMJPIvQs 7en4PpSO9XF8TsZ40GGzEkvO6b+Mmm51t8+1Yzv8DC2JU5ad4bZdhLr1mlAID45h6d 4Q6cA5o1SdALaYV6boD82uEYsmQW0ztyIECKBsbs= Date: Mon, 20 Mar 2023 14:28:01 +0100 From: Greg KH To: John Harrison Message-ID: References: <167820543971229@kroah.com> <20230314022211.1393031-1-John.C.Harrison@Intel.com> <5ed286b7-c2df-9e63-d85a-be9994f93eec@intel.com> <17301b8c-19e0-4364-3e4c-c1c3d8cc45aa@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <17301b8c-19e0-4364-3e4c-c1c3d8cc45aa@intel.com> Subject: Re: [Intel-gfx] [PATCH 5.4.y] drm/i915: Don't use BAR mappings for ring buffers with LLC X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jani Nikula , intel-gfx@lists.freedesktop.org, stable@vger.kernel.org, Rodrigo Vivi Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" On Fri, Mar 17, 2023 at 09:07:50PM -0700, John Harrison wrote: > On 3/17/2023 05:58, Greg KH wrote: > > On Thu, Mar 16, 2023 at 01:58:35PM -0700, John Harrison wrote: > > > On 3/15/2023 10:57, Greg KH wrote: > > > > On Wed, Mar 15, 2023 at 10:07:53AM -0700, John Harrison wrote: > > > > > On 3/15/2023 00:51, Greg KH wrote: > > > > > > On Mon, Mar 13, 2023 at 07:22:11PM -0700, John.C.Harrison@Intel.com wrote: > > > > > > > From: John Harrison > > > > > > > > > > > > > > Direction from hardware is that ring buffers should never be mapped > > > > > > > via the BAR on systems with LLC. There are too many caching pitfalls > > > > > > > due to the way BAR accesses are routed. So it is safest to just not > > > > > > > use it. > > > > > > > > > > > > > > Signed-off-by: John Harrison > > > > > > > Fixes: 9d80841ea4c9 ("drm/i915: Allow ringbuffers to be bound anywhere") > > > > > > > Cc: Chris Wilson > > > > > > > Cc: Joonas Lahtinen > > > > > > > Cc: Jani Nikula > > > > > > > Cc: Rodrigo Vivi > > > > > > > Cc: Tvrtko Ursulin > > > > > > > Cc: intel-gfx@lists.freedesktop.org > > > > > > > Cc: # v4.9+ > > > > > > > Tested-by: Jouni Högander > > > > > > > Reviewed-by: Daniele Ceraolo Spurio > > > > > > > Link: https://patchwork.freedesktop.org/patch/msgid/20230216011101.1909009-3-John.C.Harrison@Intel.com > > > > > > > (cherry picked from commit 65c08339db1ada87afd6cfe7db8e60bb4851d919) > > > > > > > Signed-off-by: Jani Nikula > > > > > > > (cherry picked from commit 85636167e3206c3fbd52254fc432991cc4e90194) > > > > > > > Signed-off-by: John Harrison > > > > > > > --- > > > > > > > drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 ++-- > > > > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > Also queued up for 5.10.y, you forgot that one :) > > > > > I'm still working through the backlog of them. > > > > > > > > > > Note that these patches must all be applied as a pair. The 'don't use > > > > > stolen' can be applied in isolation but won't totally fix the problem. > > > > > However, applying 'don't use BAR mappings' without applying the stolen patch > > > > > first will results in problems such as the failure to boot that was recently > > > > > reported and resulted in a revert in one of the trees. > > > > I do not understand, you only submitted 1 patch here, what is the > > > > "pair"? > > > The original patch series was two patches - > > > https://patchwork.freedesktop.org/series/114080/. One to not use stolen > > > memory and the other to not use BAR mappings. If the anti-BAR patch is > > > applied without the anti-stolen patch then the i915 driver will attempt to > > > access stolen memory directly which will fail. So both patches must be > > > applied and in the correct order to fix the problem of cache aliasing when > > > using BAR accesses on LLC systems. > > > > > > As above, I am working my way through the bunch of 'FAILED patch' emails. > > > The what-to-do instructions in those emails explicitly say to send the patch > > > individually in reply to the 'FAILED' message rather than as part of any > > > original series. > > So what commits exactly in Linus's tree should be in these stable > > branches? Sorry, I still do not understand if we are missing one or if > > we need to revert something. > > > > confused, > > > > greg k-h > As far as I can tell, I have replied to all the "FAILED: patch" emails now. > There should be a versions of these two patches available for all trees > (being 4.14, 4.19, 5.4, 5.10 and 5.15): >     690e0ec8e63d drm/i915: Don't use stolen memory for ring buffers with LLC Your backports of this are all now queued up, thanks. greg k-h