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[209.132.180.67]) by mx.google.com with ESMTP id e20si1157598oig.199.2020.02.27.04.17.11; Thu, 27 Feb 2020 04:17:24 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail (test mode) header.i=@shipmail.org header.s=mail header.b=gLbEzXfu; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728950AbgB0MQw (ORCPT + 99 others); Thu, 27 Feb 2020 07:16:52 -0500 Received: from ste-pvt-msa1.bahnhof.se ([213.80.101.70]:60677 "EHLO ste-pvt-msa1.bahnhof.se" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728856AbgB0MQw (ORCPT ); Thu, 27 Feb 2020 07:16:52 -0500 Received: from localhost (localhost [127.0.0.1]) by ste-pvt-msa1.bahnhof.se (Postfix) with ESMTP id 620A23FD5F; Thu, 27 Feb 2020 13:16:49 +0100 (CET) Authentication-Results: ste-pvt-msa1.bahnhof.se; dkim=pass (1024-bit key; unprotected) header.d=shipmail.org header.i=@shipmail.org header.b=gLbEzXfu; dkim-atps=neutral X-Virus-Scanned: Debian amavisd-new at bahnhof.se X-Spam-Flag: NO X-Spam-Score: -2.099 X-Spam-Level: X-Spam-Status: No, score=-2.099 tagged_above=-999 required=6.31 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, URIBL_BLOCKED=0.001] autolearn=ham autolearn_force=no Received: from ste-pvt-msa1.bahnhof.se ([127.0.0.1]) by localhost (ste-pvt-msa1.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rfGpzPSC_Tad; Thu, 27 Feb 2020 13:16:48 +0100 (CET) Received: from mail1.shipmail.org (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) (Authenticated sender: mb878879) by ste-pvt-msa1.bahnhof.se (Postfix) with ESMTPA id B73293F622; Thu, 27 Feb 2020 13:16:46 +0100 (CET) Received: from localhost.localdomain (h-205-35.A357.priv.bahnhof.se [155.4.205.35]) by mail1.shipmail.org (Postfix) with ESMTPSA id 07765360058; Thu, 27 Feb 2020 13:16:46 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=shipmail.org; s=mail; t=1582805806; bh=HS94RJPImzDoQLY2q4Ne/b5a9NMsxYAfRk+4BrMewsw=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=gLbEzXfuzrAyw9EoRIHV1y36EvZXgzqWODh7uN9Np4P9BOcC3coXG7IQxrWeJsq3B bmwBK/ss7x+uwsleuEHkleUDcAYo5ayY+0hUiPO6JEA3VFA6oCzv8nIz467Mo9yiL7 6hul+ss9vMywmIcQvCaux0tUk+2Pynh9sJKcBeTU= Subject: Re: [PATCH v5 1/3] drm/shmem: add support for per object caching flags. To: Gerd Hoffmann Cc: dri-devel@lists.freedesktop.org, Guillaume.Gardet@arm.com, David Airlie , open list , stable@vger.kernel.org, gurchetansingh@chromium.org, tzimmermann@suse.de References: <20200226154752.24328-1-kraxel@redhat.com> <20200226154752.24328-2-kraxel@redhat.com> <20200227075321.ki74hfjpnsqv2yx2@sirius.home.kraxel.org> <41ca197c-136a-75d8-b269-801db44d4cba@shipmail.org> <20200227105643.h4klc3ybhpwv2l3x@sirius.home.kraxel.org> From: =?UTF-8?Q?Thomas_Hellstr=c3=b6m_=28VMware=29?= Organization: VMware Inc. Message-ID: <68a05ace-40bc-76d6-5464-2c96328874b9@shipmail.org> Date: Thu, 27 Feb 2020 13:16:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20200227105643.h4klc3ybhpwv2l3x@sirius.home.kraxel.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/27/20 11:56 AM, Gerd Hoffmann wrote: > Hi, > >> I think it might be safe for some integrated graphics where the driver >> maintainers can guarantee that it's safe on all particular processors used >> with that driver, but then IMO it should be moved out to those drivers. >> >> Other drivers needing write-combine shouldn't really use shmem. >> >> So again, to fix the regression, could we revert 0be895893607f ("drm/shmem: >> switch shmem helper to &drm_gem_object_funcs.mmap") or does that have other >> implications? > This patch isn't a regression. The old code path has the > pgprot_writecombine() call in drm_gem_mmap_obj(), so the behavior > is the same before and afterwards. OK. I wasn't checking where this all came from from the start... > But with the patch in place we can easily have shmem helpers do their > own thing instead of depending on whatever drm_gem_mmap_obj() is doing. > Just using cached mappings unconditionally would be perfectly fine for > virtio-gpu. > > Not sure about the other users though. I'd like to fix the virtio-gpu > regression (coming from ttm -> shmem switch) asap, and I don't feel like > changing the behavior for other drivers in 5.6-rc is a good idea. > > So I'd like to push patches 1+2 to -fixes and sort everything else later > in -next. OK? OK with me. Do we have any idea what drivers are actually using write-combine and decrypted? /Thomas > > cheers, > Gerd