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 2E9F5C282DE for ; Sat, 8 Mar 2025 00:02:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CB96510EBBB; Sat, 8 Mar 2025 00:02:20 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="Di7273GE"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.14]) by gabe.freedesktop.org (Postfix) with ESMTPS id 21DB110EC51 for ; Sat, 8 Mar 2025 00:02:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1741392139; x=1772928139; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=wK3GVZzhziijazLabdBsnWr6nEMLLB1zlDjXG/Spqm4=; b=Di7273GE5D/oVqnFJ5shlp/Socmvf7aTsjqpyeagP4E5GnhhMFf2vGsJ BvMKwEEhW4FCNlxOIoXjFUR5xVIY6pj16IkPc/t5LBy9pctE0e+TcAkpO SKaYDJWdIHrbHEGX2Z+lATIv50nBOsGka9U5FTkjF7sIgqNaabyjchlCz ZPjbghTK2XVy4CwqztL7lh4XFSNot/j5TjW2eGJfq+WMvOPx1IJ0zvnbn GjjN76GybcSyOgAIvD+xzkvqoldIFKbjrB0oDqpys9OXcjp1CNfz1ANuR H2XR8QPIpTTRVAw5+EtQQkadOj2Kq9WKL/2E5uTdvLK38qnl+6I+E8hwh A==; X-CSE-ConnectionGUID: dWFBkNWVRFWW83yVSPoDiA== X-CSE-MsgGUID: xOru/VI0SwOpXGXTSTFfvQ== X-IronPort-AV: E=McAfee;i="6700,10204,11366"; a="42680419" X-IronPort-AV: E=Sophos;i="6.14,230,1736841600"; d="scan'208";a="42680419" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by fmvoesa108.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2025 16:02:16 -0800 X-CSE-ConnectionGUID: NvkgSHnfSQis0ysv6QKXfA== X-CSE-MsgGUID: GioDAiD3SZm0DNeBaHBg/g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,230,1736841600"; d="scan'208";a="119283091" Received: from szeng-desk.jf.intel.com ([10.165.21.160]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Mar 2025 16:02:16 -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 v8 3/3] drm/xe: Allow scratch page under fault mode for certain platform Date: Fri, 7 Mar 2025 19:18:29 -0500 Message-Id: <20250308001829.1459320-4-oak.zeng@intel.com> X-Mailer: git-send-email 2.26.3 In-Reply-To: <20250308001829.1459320-1-oak.zeng@intel.com> References: <20250308001829.1459320-1-oak.zeng@intel.com> MIME-Version: 1.0 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. v2: Refine commit message (Thomas) v3: Move the scratch page flag check to after scratch page wa (Thomas) v4: drop NEEDS_SCRATCH macro (matt) Add a comment to DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE Signed-off-by: Oak Zeng Reviewed-by: Matthew Brost --- drivers/gpu/drm/xe/xe_vm.c | 3 ++- include/uapi/drm/xe_drm.h | 6 +++++- 2 files changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c index 3e5dfce6f18a..f33ec3f1ac11 100644 --- a/drivers/gpu/drm/xe/xe_vm.c +++ b/drivers/gpu/drm/xe/xe_vm.c @@ -2049,7 +2049,8 @@ int xe_vm_create_ioctl(struct drm_device *dev, void *data, return -EINVAL; if (XE_IOCTL_DBG(xe, args->flags & DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE && - args->flags & DRM_XE_VM_CREATE_FLAG_FAULT_MODE)) + args->flags & DRM_XE_VM_CREATE_FLAG_FAULT_MODE && + !xe->info.needs_scratch)) return -EINVAL; if (XE_IOCTL_DBG(xe, !(args->flags & DRM_XE_VM_CREATE_FLAG_LR_MODE) && diff --git a/include/uapi/drm/xe_drm.h b/include/uapi/drm/xe_drm.h index 616916985e3f..9c08738c3b91 100644 --- a/include/uapi/drm/xe_drm.h +++ b/include/uapi/drm/xe_drm.h @@ -917,7 +917,11 @@ struct drm_xe_gem_mmap_offset { * struct drm_xe_vm_create - Input of &DRM_IOCTL_XE_VM_CREATE * * The @flags can be: - * - %DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE + * - %DRM_XE_VM_CREATE_FLAG_SCRATCH_PAGE - Map the whole virtual address + * space of the VM to scratch page. A vm_bind would overwrite the scratch + * page mapping. This flag is mutually exclusive with the + * %DRM_XE_VM_CREATE_FLAG_FAULT_MODE flag, with an exception of on x2 and + * xe3 platform. * - %DRM_XE_VM_CREATE_FLAG_LR_MODE - An LR, or Long Running VM accepts * exec submissions to its exec_queues that don't have an upper time * limit on the job execution time. But exec submissions to these -- 2.26.3