From nobody Wed Dec 17 12:14:25 2025 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 295F8C4167B for ; Sun, 26 Nov 2023 16:37:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230209AbjKZQht (ORCPT ); Sun, 26 Nov 2023 11:37:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229437AbjKZQhs (ORCPT ); Sun, 26 Nov 2023 11:37:48 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 22BB0D7 for ; Sun, 26 Nov 2023 08:37:55 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2236C433C7; Sun, 26 Nov 2023 16:37:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701016674; bh=14LKXLMt/+5p7qNVS51zb2f8quhJJfzs+4w5ju16qQE=; h=From:To:Cc:Subject:Date:From; b=mt7oHGf9eqanTX1nkP81wW4zCU1I2igViCVsXynMsPOkiJ6FEJmGV3NY3UUTdBhbj 1Pj5QIjP6KqCyvS7c2o5SObZ73Os35SJblEnA86rrUC2Pq/Q6cRqf/pLj2r8cvXTKI J9ojaEZvebtfR1eAn00K/dtPAx6ldxX9WhHRCOP7ZYJ4D5xWD/dd2sk0MTqLmpR2sf y0FH0hkb9xRAWaNDFq91uV+HkipxIhLnGdQGEZe4pCGvxQaVoyrhPSsE07JFRUwqTa icYlYgsGQWf5zPKFq/5j2XdxddlL7yX5q4BjVli5kdSgsECw7Dtbrwfta+pHqpCYXi yfPhtdRPfHtjw== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] riscv: mm: still create swiotlb buffer for kmalloc() bouncing if required Date: Mon, 27 Nov 2023 00:25:28 +0800 Message-Id: <20231126162528.2411-1-jszhang@kernel.org> X-Mailer: git-send-email 2.40.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" After commit f51f7a0fc2f4 ("riscv: enable DMA_BOUNCE_UNALIGNED_KMALLOC for !dma_coherent"), for non-coherent platforms with less than 4GB memory, we rely on users to pass "swiotlb=3Dmmnn,force" kernel parameters to enable DMA bouncing for unaligned kmalloc() buffers. Now let's go further: If no bouncing needed for ZONE_DMA, let kernel automatically allocate 1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing on non-coherent platforms, so that no need to pass "swiotlb=3Dmmnn,force" any more. The math of "1MB swiotlb buffer per 1GB of RAM for kmalloc() bouncing" is taken from arm64. Users can still force smaller swiotlb buffer by passing "swiotlb=3Dmmnn". Signed-off-by: Jisheng Zhang --- arch/riscv/mm/init.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 2e011cbddf3a..cbcb9918f721 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -162,11 +162,25 @@ static void print_vm_layout(void) { } =20 void __init mem_init(void) { + bool swiotlb =3D max_pfn > PFN_DOWN(dma32_phys_limit); #ifdef CONFIG_FLATMEM BUG_ON(!mem_map); #endif /* CONFIG_FLATMEM */ =20 - swiotlb_init(max_pfn > PFN_DOWN(dma32_phys_limit), SWIOTLB_VERBOSE); + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb && + dma_cache_alignment !=3D 1) { + /* + * If no bouncing needed for ZONE_DMA, allocate 1MB swiotlb + * buffer per 1GB of RAM for kmalloc() bouncing on + * non-coherent platforms. + */ + unsigned long size =3D + DIV_ROUND_UP(memblock_phys_mem_size(), 1024); + swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); + swiotlb =3D true; + } + + swiotlb_init(swiotlb, SWIOTLB_VERBOSE); memblock_free_all(); =20 print_vm_layout(); --=20 2.42.0