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 7C74FC43334 for ; Wed, 6 Jul 2022 07:02:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231226AbiGFHCS (ORCPT ); Wed, 6 Jul 2022 03:02:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55354 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231180AbiGFHCQ (ORCPT ); Wed, 6 Jul 2022 03:02:16 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e5ab]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D503205DD; Wed, 6 Jul 2022 00:02:15 -0700 (PDT) Received: from [192.168.2.145] (109-252-119-232.nat.spd-mgts.ru [109.252.119.232]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id 032266601824; Wed, 6 Jul 2022 08:02:11 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1657090933; bh=3kFIlo73JPC7k/gbRqw+WxdlGeaZ8IxSG90hClRzzNw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=PqIJtSXmD51oSDnhPr7cbQ3HgaDU2VJvXoQA9lI06vBnDG8++5DkjbQ0zfgstkebX Bhz9kmfxSmZXElA9X1M30fK8vd3DB8gIiZs+2JrdniTHTN9R73jQPhkfMI73jLXYt6 1IpiM0aMkRVDA+7yEeuOIl/hTXWIl3qocO2GDA/46JXb5nXoyjMPLHj4zvCeFeKh0L SfPQkBm0s2JCZzAwk4r+dN5gGF7ORUKOuq0L5TN/b5Kaw2bAbroGhwAnmzrNm3YPJR Zxa5hBOoIUCmZg9mRAoEnLZzU9gfOXVsL5O6ZLz+UonU4Yh+EW/pnx+SYBhucehaS+ JpYgWgnItX2Pw== Message-ID: <2a646ce4-c2ec-3b11-77a0-cc720afd6fe1@collabora.com> Date: Wed, 6 Jul 2022 10:02:07 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v8 2/2] drm/gem: Don't map imported GEMs Content-Language: en-US To: Rob Clark , =?UTF-8?Q?Christian_K=c3=b6nig?= Cc: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Emil Velikov , =?UTF-8?Q?Thomas_Hellstr=c3=b6m?= , Linux Kernel Mailing List , dri-devel , "open list:VIRTIO GPU DRIVER" , linux-tegra@vger.kernel.org, Dmitry Osipenko , kernel@collabora.com References: <20220701090240.1896131-1-dmitry.osipenko@collabora.com> <20220701090240.1896131-3-dmitry.osipenko@collabora.com> <2bb95e80-b60a-36c0-76c8-a06833032c77@amd.com> From: Dmitry Osipenko In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/6/22 00:48, Rob Clark wrote: > On Tue, Jul 5, 2022 at 4:51 AM Christian König wrote: >> >> Am 01.07.22 um 11:02 schrieb Dmitry Osipenko: >>> Drivers that use drm_gem_mmap() and drm_gem_mmap_obj() helpers don't >>> handle imported dma-bufs properly, which results in mapping of something >>> else than the imported dma-buf. On NVIDIA Tegra we get a hard lockup when >>> userspace writes to the memory mapping of a dma-buf that was imported into >>> Tegra's DRM GEM. >>> >>> Majority of DRM drivers prohibit mapping of the imported GEM objects. >>> Mapping of imported GEMs require special care from userspace since it >>> should sync dma-buf because mapping coherency of the exporter device may >>> not match the DRM device. Let's prohibit the mapping for all DRM drivers >>> for consistency. >>> >>> Suggested-by: Thomas Hellström >>> Signed-off-by: Dmitry Osipenko >> >> I'm pretty sure that this is the right approach, but it's certainly more >> than possible that somebody abused this already. > > I suspect that this is abused if you run deqp cts on android.. ie. all > winsys buffers are dma-buf imports from gralloc. And then when you > hit readpix... > > You might only hit this in scenarios with separate gpu and display (or > dGPU+iGPU) because self-imports are handled differently in > drm_gem_prime_import_dev().. and maybe not in cases where you end up > with a blit from tiled/compressed to linear.. maybe that narrows the > scope enough to just fix it in userspace? Given that that only drivers which use DRM-SHMEM potentially could've map imported dma-bufs (Panfrost, Lima) and they already don't allow to do that, I think we're good. -- Best regards, Dmitry