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 12FB7CCD1BA for ; Tue, 21 Oct 2025 11:31:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id C6F1610E5C1; Tue, 21 Oct 2025 11:31:06 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=collabora.com header.i=@collabora.com header.b="JBo247+a"; dkim-atps=neutral Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0277C10E5B4; Tue, 21 Oct 2025 11:31:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1761046258; bh=b5DjKy8Ku5W6YjxLJ5sbdp7mTOI5CNz17N4tCTUcgu8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JBo247+aL1JX25fByWt1HEwt3SEbx1YeMbAdQ0IqQ67eXRvH9z9JYIOkfGwTd+U8l QiIDDrF74o723OS5FwS7yv15E72pHMPEq4cdEVkVsxqkLq4zTH/K0PFuHLNWwb0i6r jwrMmgi5KWer3/K585iB6n3sFieDrCdYYINNW7Qkaz9F4AXfUL1reEx00L+3Vu8kT7 hzKIdP4jN24BBm25ssnHeSV9uVYyn33s/mYOtZgxkhLnoFjzu65AHsB25SIlYwL3FX g9jSs0j2u6AsE/oI/z4fSiiKG06CTZQtgtO78ervT37fjs3alX+3CkWciZc4HxbHWA mTb0hr/n2bIvQ== 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 BFFB917E1407; Tue, 21 Oct 2025 13:30:57 +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 03/12] drm/shmem-helper: Map huge pages in fault handlers Date: Tue, 21 Oct 2025 13:30:40 +0200 Message-ID: <20251021113049.17242-4-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" Check whether the starting address in the fault-around handler or the faulty address in the fault handler is part of a huge page in order to attempt a PMD sized PFN insertion into the VMA. On builds with CONFIG_TRANSPARENT_HUGEPAGE enabled, if the mmap() user address is PMD size aligned, if the GEM object is backed by shmem buffers on mountpoints setting the 'huge=' option and if the shmem backing store manages to allocate a huge folio, CPU mapping would then benefit from significantly increased memcpy() performance. When these conditions are met on a system with 2 MiB huge pages, an aligned copy of 2 MiB would raise a single page fault instead of 4096. v4: - implement map_pages instead of huge_fault Signed-off-by: Loïc Molinari --- drivers/gpu/drm/drm_gem_shmem_helper.c | 30 ++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 2a9fbc9c3712..b7238448d4f9 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -580,6 +580,26 @@ static bool drm_gem_shmem_fault_is_valid(struct drm_gem_object *obj, return true; } +static bool drm_gem_shmem_map_pmd(struct vm_fault *vmf, unsigned long addr, + struct page *page) +{ +#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP + unsigned long pfn = page_to_pfn(page); + unsigned long paddr = pfn << PAGE_SHIFT; + bool aligned = (addr & ~PMD_MASK) == (paddr & ~PMD_MASK); + + if (aligned && + pmd_none(*vmf->pmd) && + folio_test_pmd_mappable(page_folio(page))) { + pfn &= PMD_MASK >> PAGE_SHIFT; + if (vmf_insert_pfn_pmd(vmf, pfn, false) == VM_FAULT_NOPAGE) + return true; + } +#endif + + return false; +} + static vm_fault_t drm_gem_shmem_map_pages(struct vm_fault *vmf, pgoff_t start_pgoff, pgoff_t end_pgoff) @@ -606,6 +626,11 @@ static vm_fault_t drm_gem_shmem_map_pages(struct vm_fault *vmf, goto out; } + if (drm_gem_shmem_map_pmd(vmf, addr, pages[start_pgoff])) { + ret = VM_FAULT_NOPAGE; + goto out; + } + /* Map a range of pages around the faulty address. */ do { pfn = page_to_pfn(pages[start_pgoff]); @@ -639,6 +664,11 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) goto out; } + if (drm_gem_shmem_map_pmd(vmf, vmf->address, pages[page_offset])) { + ret = VM_FAULT_NOPAGE; + goto out; + } + pfn = page_to_pfn(pages[page_offset]); ret = vmf_insert_pfn(vma, vmf->address, pfn); -- 2.47.3