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 8F735CCD1AB for ; Tue, 21 Oct 2025 11:31:02 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 04D7A10E5B8; Tue, 21 Oct 2025 11:31:00 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="jkEGlLvJ"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 11F7010E5B8; Tue, 21 Oct 2025 11:30:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1761046257; bh=KOWDNuw2RyynKmJ4ZsE60XfwYk9U21BJtK/dnqbhV5M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jkEGlLvJpL5ipkJhIbJS1NwsbTwZgBAiguvdFmT0Nrqj06FOVmUzTIWBEcuNmQBk8 GEDWAi9ffa5cUQhGgT5n7+VowfmdGSL99UAfy4SCACh7QyOhfvA+q+Sx4VNM6vah1p TZyULGL0sK0Gf8OSBJDt1Z6OSbOo1x5ck3NP+Go821cvK0Cp22bfiYQ1T9QI65iGXT KT90nErM0JkINFpGUfL1KglP4AaAgr1ukN37aLDcsHac/I3VzPt9Bx+cLChW1OjxSa rZRTmqatrZkOTx02CzNmrOSNrtB0O7nhwSis/C/pHb6G6jeTfn993Bl0m+kSqjot2q z5hExxJfWZ56g== Received: from debian-rockchip-rock5b-rk3588.. (unknown [IPv6:2a01:e0a:5e3:6100:826d:bc07:e98c:84a]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: loicmolinari) by bali.collaboradmins.com (Postfix) with ESMTPSA id BB76A17E1404; Tue, 21 Oct 2025 13:30:56 +0200 (CEST) From: =?UTF-8?q?Lo=C3=AFc=20Molinari?= To: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , Boris Brezillon , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?q?Ma=C3=ADra=20Canal?= , Hugh Dickins , Baolin Wang , Andrew Morton , =?UTF-8?q?Lo=C3=AFc=20Molinari?= , Al Viro , =?UTF-8?q?Miko=C5=82aj=20Wasiak?= , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, kernel@collabora.com Subject: [PATCH v5 02/12] drm/shmem-helper: Implement map_pages fault-around handler Date: Tue, 21 Oct 2025 13:30:39 +0200 Message-ID: <20251021113049.17242-3-loic.molinari@collabora.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251021113049.17242-1-loic.molinari@collabora.com> References: <20251021113049.17242-1-loic.molinari@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" This gives the mm subsystem the ability to increase fault handling performance by proposing the insertion of a range of pages around the faulty address in a single batch. v4: - implement map_pages instead of huge_fault v5: - improve patch series progression - use dma_resv_trylock() in map_pages (many thanks to Matthew Wilcox) - validate map_pages range based on end_pgoff instead of start_pgoff Signed-off-by: Loïc Molinari --- drivers/gpu/drm/drm_gem_shmem_helper.c | 72 ++++++++++++++++++++++---- 1 file changed, 62 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index be89be1c804c..2a9fbc9c3712 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -567,31 +567,82 @@ int drm_gem_shmem_dumb_create(struct drm_file *file, struct drm_device *dev, } EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create); -static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) +static bool drm_gem_shmem_fault_is_valid(struct drm_gem_object *obj, + pgoff_t pgoff) +{ + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); + + if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages) || + pgoff >= (obj->size >> PAGE_SHIFT) || + shmem->madv < 0) + return false; + + return true; +} + +static vm_fault_t drm_gem_shmem_map_pages(struct vm_fault *vmf, + pgoff_t start_pgoff, + pgoff_t end_pgoff) { struct vm_area_struct *vma = vmf->vma; struct drm_gem_object *obj = vma->vm_private_data; struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); - loff_t num_pages = obj->size >> PAGE_SHIFT; + struct page **pages = shmem->pages; + unsigned long addr, pfn; vm_fault_t ret; - struct page *page; + + start_pgoff -= vma->vm_pgoff; + end_pgoff -= vma->vm_pgoff; + addr = vma->vm_start + (start_pgoff << PAGE_SHIFT); + + /* map_pages is called with the RCU lock for reading (sleep isn't + * allowed) so just fall through to the more heavy-weight fault path. + */ + if (unlikely(!dma_resv_trylock(shmem->base.resv))) + return 0; + + if (unlikely(!drm_gem_shmem_fault_is_valid(obj, end_pgoff))) { + ret = VM_FAULT_SIGBUS; + goto out; + } + + /* Map a range of pages around the faulty address. */ + do { + pfn = page_to_pfn(pages[start_pgoff]); + ret = vmf_insert_pfn(vma, addr, pfn); + addr += PAGE_SIZE; + } while (++start_pgoff <= end_pgoff && ret == VM_FAULT_NOPAGE); + + out: + dma_resv_unlock(shmem->base.resv); + + return ret; +} + +static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct drm_gem_object *obj = vma->vm_private_data; + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); + struct page **pages = shmem->pages; pgoff_t page_offset; + unsigned long pfn; + vm_fault_t ret; /* Offset to faulty address in the VMA (without the fake offset). */ page_offset = vmf->pgoff - vma->vm_pgoff; dma_resv_lock(shmem->base.resv, NULL); - if (page_offset >= num_pages || - drm_WARN_ON_ONCE(obj->dev, !shmem->pages) || - shmem->madv < 0) { + if (unlikely(!drm_gem_shmem_fault_is_valid(obj, page_offset))) { ret = VM_FAULT_SIGBUS; - } else { - page = shmem->pages[page_offset]; - - ret = vmf_insert_pfn(vma, vmf->address, page_to_pfn(page)); + goto out; } + pfn = page_to_pfn(pages[page_offset]); + ret = vmf_insert_pfn(vma, vmf->address, pfn); + + out: dma_resv_unlock(shmem->base.resv); return ret; @@ -632,6 +683,7 @@ static void drm_gem_shmem_vm_close(struct vm_area_struct *vma) } const struct vm_operations_struct drm_gem_shmem_vm_ops = { + .map_pages = drm_gem_shmem_map_pages, .fault = drm_gem_shmem_fault, .open = drm_gem_shmem_vm_open, .close = drm_gem_shmem_vm_close, -- 2.47.3