From patchwork Mon Feb 27 20:40:00 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Andr=C3=A9_Almeida?= X-Patchwork-Id: 13154173 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 1F338C64ED6 for ; Mon, 27 Feb 2023 20:40:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2779F10E429; Mon, 27 Feb 2023 20:40:16 +0000 (UTC) Received: from fanzine2.igalia.com (fanzine2.igalia.com [213.97.179.56]) by gabe.freedesktop.org (Postfix) with ESMTPS id 086CD10E418; Mon, 27 Feb 2023 20:40:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=igalia.com; s=20170329; h=Content-Transfer-Encoding:Content-Type:MIME-Version:References: In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=PCbb2BiC5iSOL8kwHoBIumUlWcLk+H657ge7raRiJao=; b=kTSICWqflGTdsSt539NcYACUrW vjripr70AuX6Pr9oATfuY/txFwIPQELz0KLA1yEOEpkryga+NjalEfXWx4FZU75N6YQJH+7PCTuXR xuoUhUqFb+KjkKO5AFKphB/icMd+IEWlP7hxVWJtDFtdRXaEW8VzbqAg0Z9jXCiVgw7jkTwheWMla 6VOG2/7S9Q8ckGbsY4OTJSoW0L38Cq3gVuWYyQ551pvqBJhpQG0eNj4CFa3h+mEcbn5uPegg6K5ag E39dm7+WDMwAeX15uBd2cICUmmELP7JxGgxbR7lJdMUg6G7FwbBni97gkmTDMA3muUZrxiMvAyXnM p5bz8HxA==; Received: from [181.199.58.72] (helo=localhost.localdomain) by fanzine2.igalia.com with esmtpsa (Cipher TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim) id 1pWkI6-00H62x-3e; Mon, 27 Feb 2023 21:40:10 +0100 From: =?utf-8?q?Andr=C3=A9_Almeida?= To: dri-devel@lists.freedesktop.org, amd-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 1/1] drm/doc: Document DRM device reset expectations Date: Mon, 27 Feb 2023 15:40:00 -0500 Message-Id: <20230227204000.56787-2-andrealmeid@igalia.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230227204000.56787-1-andrealmeid@igalia.com> References: <20230227204000.56787-1-andrealmeid@igalia.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pierre-eric.pelloux-prayer@amd.com, =?utf-8?q?Andr=C3=A9_Almeida?= , =?utf-8?b?TWFyZWsg?= =?utf-8?b?T2zFocOhaw==?= , amaranath.somalapuram@amd.com, Pekka Paalanen , kernel-dev@igalia.com, alexander.deucher@amd.com, contactshashanksharma@gmail.com, christian.koenig@amd.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Create a section that specifies how to deal with DRM device resets for kernel and userspace drivers. Signed-off-by: André Almeida --- Documentation/gpu/drm-uapi.rst | 51 ++++++++++++++++++++++++++++++++++ 1 file changed, 51 insertions(+) diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst index 65fb3036a580..3d6c3ed392ea 100644 --- a/Documentation/gpu/drm-uapi.rst +++ b/Documentation/gpu/drm-uapi.rst @@ -285,6 +285,57 @@ for GPU1 and GPU2 from different vendors, and a third handler for mmapped regular files. Threads cause additional pain with signal handling as well. +Device reset +============ + +The GPU stack is really complex and is prone to errors, from hardware bugs, +faulty applications and everything in the many layers in between. To recover +from this kind of state, sometimes is needed to reset the GPU. Unproper handling +of GPU resets can lead to an unstable userspace. This section describes what's +the expected behaviour from DRM drivers to do in those situations, from usermode +drivers and compositors as well. The end goal is to have a seamless experience +as possible, either the stack being able to recover itself or resetting to a new +stable state. + +Robustness +---------- + +First of all, application robust APIs, when available, should be used. This +allows the application to correctly recover and continue to run after a reset. +Apps that doesn't use this should be promptly killed when the kernel driver +detects that it's in broken state. Specifically guidelines for some APIs: + +- OpenGL: KMD signals the abortion of submitted commands and the UMD should then + react accordingly and abort the application. + +- Vulkan: Assumes that every app is able to deal with ``VK_ERROR_DEVICE_LOST``. + If it doesn't do it right, it's considered a broken application and UMD will + deal with it, aborting it. + +Kernel mode driver +------------------ + +The KMD must be able to detect that something is wrong with the application +and that a reset is needed to take place to recover the device (e.g. an endless +wait). It needs to properly track the context that is broken and mark it as +dead, so any other syscalls to that context should be further rejected. The +other contexts should be preserved when possible, avoid crashing the rest of +userspace. KMD can ban a file descriptor that keeps causing resets, as it's +likely in a broken loop. + +User mode driver +---------------- + +During a reset, UMD should be aware that rejected syscalls indicates that the +context is broken and for robust apps the recovery should happen for the +context. Non-robust apps must be terminated. + +Compositors +----------- + +Compositors should be robust as well to properly deal with its errors. + + .. _drm_driver_ioctl: IOCTL Support on Device Nodes