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 DACBDCD8CB2 for ; Wed, 10 Jun 2026 13:35:27 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 7BEC810E06B; Wed, 10 Jun 2026 13:35:27 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="maBV4ucP"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.15]) by gabe.freedesktop.org (Postfix) with ESMTPS id 41A5689F35 for ; Wed, 10 Jun 2026 13:35:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1781098526; x=1812634526; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=rovOE6ZlHkILxYp8p6BMF1ESlZyGUX3cWZWYFYRohjU=; b=maBV4ucPURhuQBhrWmupovgA54fEGluiuj2m+exXuYI/YOOG9jpaIeDu gMM2CXjlCYpirgIhK1eM+WBn98oWLKDrAtluG0Glx2X937l6bfocDQ24E zl9U4ARML/C6nULKMVa5P5Z6rZaETYatSSXHLr43HQ4HecpKMs21xWsBp 8Ovsax06fuwgfv89irgO7/gHByQk4vfbOf6okAeAKgK7f+szg6rJa8rYE gmiOZVovfBM5H0NG+/abQ9oBbrQRSi2UVG5oF44//9WW789Nm9ji7ivCW tLzhhtQO0eZ8xfTL7HjVNG+BulyjeYAyAFTu5/9CydhUlcr8h1bDAFH/w w==; X-CSE-ConnectionGUID: 9jrBBhmhTlCSDmYPOBlvdg== X-CSE-MsgGUID: 0VbOjcwUTxCiYzx8BCM3Bg== X-IronPort-AV: E=McAfee;i="6800,10657,11812"; a="82000104" X-IronPort-AV: E=Sophos;i="6.24,197,1774335600"; d="scan'208";a="82000104" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa109.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2026 06:35:26 -0700 X-CSE-ConnectionGUID: 4dPihA+2Q4uEOMYJzzFaGg== X-CSE-MsgGUID: XGNp2b2iT9e1UQTp3YMN2w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,197,1774335600"; d="scan'208";a="245326417" Received: from egrumbac-mobl6.ger.corp.intel.com (HELO fedora) ([10.245.244.27]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 10 Jun 2026 06:35:25 -0700 From: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= To: intel-xe@lists.freedesktop.org Cc: =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= Subject: [RFC PATCH 1/2] drm/gpusvm: Add a DMA-mapping accounting callback Date: Wed, 10 Jun 2026 15:34:50 +0200 Message-ID: <20260610133451.8930-1-thomas.hellstrom@linux.intel.com> X-Mailer: git-send-email 2.54.0 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" Drivers that use the GPU SVM core to DMA-map system memory for GPU access may want to keep track of how many pages they have mapped, for example to expose statistics or to detect leaks. Doing this accounting in the driver around drm_gpusvm_get_pages() / drm_gpusvm_unmap_pages() is error prone: the number, order and kind of the dma_addr[] entries can change between map and unmap (migration, partial unmaps, the iova vs non-iova paths), which makes symmetric accounting hard to get right. Add an optional @dma_map_account callback to struct drm_gpusvm_ops and invoke it once per &drm_pagemap_addr entry at the exact points where the entry is DMA-mapped (sign == +1) in drm_gpusvm_get_pages() and unmapped (sign == -1) in __drm_gpusvm_unmap_pages(). Since the map error path and every unmap/free path funnel through __drm_gpusvm_unmap_pages() for the entries that were actually mapped, the accounting is symmetric by construction. The callback receives the full &drm_pagemap_addr so the driver can use the order and the proto field to distinguish system memory mappings from device interconnect mappings. The callback must also be usable by the core drm_gpusvm_pages-only API (mm == NULL), as used e.g. for userptr-style mappings. Relax drm_gpusvm_init() to allow such users to pass a restricted @ops that only implements the page-level hooks; the full-SVM hooks (@invalidate) and the chunk configuration must still be unset in that mode. Assisted-by: GitHub_Copilot:claude-opus-4.8 Signed-off-by: Thomas Hellström --- drivers/gpu/drm/drm_gpusvm.c | 17 +++++++++++++++-- include/drm/drm_gpusvm.h | 19 +++++++++++++++++++ 2 files changed, 34 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c index 958cb605aedd..c18f15c77e94 100644 --- a/drivers/gpu/drm/drm_gpusvm.c +++ b/drivers/gpu/drm/drm_gpusvm.c @@ -393,8 +393,15 @@ int drm_gpusvm_init(struct drm_gpusvm *gpusvm, return -EINVAL; mmgrab(mm); } else { - /* No full SVM mode, only core drm_gpusvm_pages API. */ - if (ops || num_chunks || mm_range || notifier_size) + /* + * No full SVM mode, only core drm_gpusvm_pages API. A + * restricted @ops that only implements the page-level hooks + * (e.g. @dma_map_account) is allowed; the full-SVM hooks must + * not be set. + */ + if (num_chunks || mm_range || notifier_size) + return -EINVAL; + if (ops && ops->invalidate) return -EINVAL; } @@ -1162,6 +1169,8 @@ static void __drm_gpusvm_unmap_pages(struct drm_gpusvm *gpusvm, else if (dpagemap && dpagemap->ops->device_unmap) dpagemap->ops->device_unmap(dpagemap, dev, addr); + if (gpusvm->ops && gpusvm->ops->dma_map_account) + gpusvm->ops->dma_map_account(gpusvm, addr, -1); i += 1 << addr->order; } @@ -1584,6 +1593,10 @@ int drm_gpusvm_get_pages(struct drm_gpusvm *gpusvm, (addr, DRM_INTERCONNECT_SYSTEM, order, dma_dir); } + if (gpusvm->ops && gpusvm->ops->dma_map_account) + gpusvm->ops->dma_map_account(gpusvm, + &svm_pages->dma_addr[j], + 1); i += 1 << order; num_dma_mapped = i; flags.has_dma_mapping = true; diff --git a/include/drm/drm_gpusvm.h b/include/drm/drm_gpusvm.h index 8a4d7134a9a7..87ad2dcaa7c4 100644 --- a/include/drm/drm_gpusvm.h +++ b/include/drm/drm_gpusvm.h @@ -75,6 +75,25 @@ struct drm_gpusvm_ops { void (*invalidate)(struct drm_gpusvm *gpusvm, struct drm_gpusvm_notifier *notifier, const struct mmu_notifier_range *mmu_range); + + /** + * @dma_map_account: Account a DMA-mapping change (optional) + * @gpusvm: Pointer to the GPU SVM + * @addr: The address descriptor of the chunk being (un)mapped + * @sign: +1 when @addr has just been DMA-mapped, -1 when it is being + * unmapped + * + * Called once per &drm_pagemap_addr entry, when the entry is + * DMA-mapped by drm_gpusvm_get_pages() (@sign == +1) and when it is + * unmapped (@sign == -1), so the driver can keep symmetric accounting + * of the pages it has mapped for GPU access. The @addr->proto field + * can be used to distinguish system-memory mappings from device + * interconnect mappings. May be provided in both full SVM mode and the + * core drm_gpusvm_pages-only mode. + */ + void (*dma_map_account)(struct drm_gpusvm *gpusvm, + const struct drm_pagemap_addr *addr, + int sign); }; /** -- 2.54.0