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 74563C19F2E for ; Thu, 27 Feb 2025 15:53:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 40E0310EB27; Thu, 27 Feb 2025 15:53:57 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="AuGc0kcn"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.20]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4AFB710E396 for ; Thu, 27 Feb 2025 15:53:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1740671630; x=1772207630; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=2La0W433SRLcI9DUlz9CyGOgQaYYHYYeekSLrRR0QxA=; b=AuGc0kcngxvWgPJh4TB3htSPxHPdiPLnr92XIXDX/OQ5wn+cQCNSveRR Xlq6vBGKnccUHeyTnWojLFLOSUR24h2F6vviegPxECdVy8iaQ+xPx/K44 OgPJ6hUEk3R8owaNHcaE3OPuBI50+fPiEkWdKd3c9MTrLv4EcPhwXnBA8 DEW2cbNtwxu3As3QmnZ/sGlnHrYo8+XQFeVYKGjAVhjuGQYtlVyUz2+Za vjCY4X8CtekqFvQII3pD2BjnNWn7Opgqhq83bSa9EHmfsa+KsgexdD/rP Or+MlffcwvzdOxSrfRi+2zOycRAkmbLn4MuMtAgnp7A0WzZdbv92w+hQV Q==; X-CSE-ConnectionGUID: i0jOTP+SSMaFif0dzpAniw== X-CSE-MsgGUID: uMafwip7QLijp4dTac0Aww== X-IronPort-AV: E=McAfee;i="6700,10204,11358"; a="41273510" X-IronPort-AV: E=Sophos;i="6.13,320,1732608000"; d="scan'208";a="41273510" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa112.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Feb 2025 07:53:50 -0800 X-CSE-ConnectionGUID: gR5/uwgBQhev9q2XYKgsiA== X-CSE-MsgGUID: pkD4T5+WSR69HoZfTXN6cA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.12,224,1728975600"; d="scan'208";a="121188672" Received: from szeng-desk.jf.intel.com ([10.165.21.160]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Feb 2025 07:53:49 -0800 From: Oak Zeng To: intel-xe@lists.freedesktop.org Cc: Thomas.Hellstrom@linux.intel.com, matthew.brost@intel.com, jonathan.cavitt@intel.com Subject: [PATCH v6 0/3] Allow scratch page under fault mode for certain platform Date: Thu, 27 Feb 2025 11:09:49 -0500 Message-Id: <20250227160952.807885-1-oak.zeng@intel.com> X-Mailer: git-send-email 2.26.3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" Normally scratch page is not allowed when a vm is operate under page fault mode, i.e., in the existing codes, DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE and DRM_XE_VM_CREATE_FLAG_FAULT_MODE are mutual exclusive. The reason is fault mode relies on recoverable page to work, while scratch page can mute recoverable page fault. On xe2 and xe3, out of bound prefetch can cause page fault and further system hang because xekmd can't resolve such page fault. SYCL and OCL language runtime requires out of bound prefetch to be silently dropped without causing any functional problem, thus the existing behavior doesn't meet language runtime requirement. At the same time, HW prefetching can cause page fault interrupt. Due to page fault interrupt overhead (i.e., need Guc and KMD involved to fix the page fault), HW prefetching can be slowed by many orders of magnitude. Fix those problems by allowing scratch page under fault mode for xe2 and xe3. With scratch page in place, HW prefetching could always hit scratch page instead of causing interrupt. A side effect is, scratch page could hide application program error. Application out of bound accesses are hided by scratch page mapping, instead of get reported to user. igt test: https://patchwork.freedesktop.org/series/144907/, Test result on BMG: root@DUT1130BMGFRD:/home/szeng/dii-tools/igt-public/build/tests# ./xe_exec_fault_mode --run-subtest scratch-fault IGT-Version: 1.30-gde1a3cb42 (x86_64) (Linux: 6.13.0-xe x86_64) Using IGT_SRANDOM=1738684805 for randomisation Opened device: /dev/dri/card0 Starting subtest: scratch-fault Subtest scratch-fault: SUCCESS (0.080s) Oak Zeng (3): drm/xe: Introduced needs_scratch bit in device descriptor drm/xe: Clear scratch page on vm_bind drm/xe: Allow scratch page under fault mode for certain platform drivers/gpu/drm/xe/xe_device_types.h | 2 + drivers/gpu/drm/xe/xe_pci.c | 5 ++ drivers/gpu/drm/xe/xe_pt.c | 93 ++++++++++++++++++---------- drivers/gpu/drm/xe/xe_vm.c | 32 ++++++++-- drivers/gpu/drm/xe/xe_vm_types.h | 2 + include/uapi/drm/xe_drm.h | 6 +- 6 files changed, 101 insertions(+), 39 deletions(-) -- 2.26.3