From patchwork Tue Oct 27 10:18:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 1388411 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4CL78x0Ksxz9sSf for ; Tue, 27 Oct 2020 21:24:01 +1100 (AEDT) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 4CL78w6JtvzDqQy for ; Tue, 27 Oct 2020 21:24:00 +1100 (AEDT) X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.ru (client-ip=107.174.27.60; helo=ozlabs.ru; envelope-from=aik@ozlabs.ru; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from ozlabs.ru (ozlabs.ru [107.174.27.60]) by lists.ozlabs.org (Postfix) with ESMTP id 4CL7385N4SzDqGb for ; Tue, 27 Oct 2020 21:19:00 +1100 (AEDT) Received: from fstn1-p1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id A3EA6AE80277; Tue, 27 Oct 2020 06:18:10 -0400 (EDT) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH kernel v2 1/2] dma: Allow mixing bypass and normal IOMMU operation Date: Tue, 27 Oct 2020 21:18:40 +1100 Message-Id: <20201027101841.96056-2-aik@ozlabs.ru> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201027101841.96056-1-aik@ozlabs.ru> References: <20201027101841.96056-1-aik@ozlabs.ru> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , iommu@lists.linux-foundation.org, Christoph Hellwig , linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" At the moment we allow bypassing DMA ops only when we can do this for the entire RAM. However there are configs with mixed type memory where we could still allow bypassing IOMMU in most cases; POWERPC with persistent memory is one example. This adds another check for the bus limit to determine where bypass can still work and we invoke direct DMA API; when DMA handle is outside that limit, we fall back to DMA ops. This adds a CONFIG_DMA_OPS_BYPASS_BUS_LIMIT config option which is off by default and will be enable for PPC_PSERIES in the following patch. Signed-off-by: Alexey Kardashevskiy --- kernel/dma/mapping.c | 61 ++++++++++++++++++++++++++++++++++++++++++-- kernel/dma/Kconfig | 4 +++ 2 files changed, 63 insertions(+), 2 deletions(-) diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 51bb8fa8eb89..0f4f998e6c72 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -137,6 +137,18 @@ static inline bool dma_map_direct(struct device *dev, return dma_go_direct(dev, *dev->dma_mask, ops); } +#ifdef CONFIG_DMA_OPS_BYPASS_BUS_LIMIT +static inline bool can_map_direct(struct device *dev, phys_addr_t addr) +{ + return dev->bus_dma_limit >= phys_to_dma(dev, addr); +} + +static inline bool dma_handle_direct(struct device *dev, dma_addr_t dma_handle) +{ + return dma_handle >= dev->archdata.dma_offset; +} +#endif + dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, size_t offset, size_t size, enum dma_data_direction dir, unsigned long attrs) @@ -151,6 +163,11 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, if (dma_map_direct(dev, ops)) addr = dma_direct_map_page(dev, page, offset, size, dir, attrs); +#ifdef CONFIG_DMA_OPS_BYPASS_BUS_LIMIT + else if (dev->bus_dma_limit && + can_map_direct(dev, (phys_addr_t) page_to_phys(page) + offset + size)) + addr = dma_direct_map_page(dev, page, offset, size, dir, attrs); +#endif else addr = ops->map_page(dev, page, offset, size, dir, attrs); debug_dma_map_page(dev, page, offset, size, dir, addr); @@ -167,6 +184,10 @@ void dma_unmap_page_attrs(struct device *dev, dma_addr_t addr, size_t size, BUG_ON(!valid_dma_direction(dir)); if (dma_map_direct(dev, ops)) dma_direct_unmap_page(dev, addr, size, dir, attrs); +#ifdef CONFIG_DMA_OPS_BYPASS_BUS_LIMIT + else if (dev->bus_dma_limit && dma_handle_direct(dev, addr + size)) + dma_direct_unmap_page(dev, addr, size, dir, attrs); +#endif else if (ops->unmap_page) ops->unmap_page(dev, addr, size, dir, attrs); debug_dma_unmap_page(dev, addr, size, dir); @@ -190,6 +211,23 @@ int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, if (dma_map_direct(dev, ops)) ents = dma_direct_map_sg(dev, sg, nents, dir, attrs); +#ifdef CONFIG_DMA_OPS_BYPASS_BUS_LIMIT + else if (dev->bus_dma_limit) { + struct scatterlist *s; + bool direct = true; + int i; + + for_each_sg(sg, s, nents, i) { + direct = can_map_direct(dev, sg_phys(s) + s->offset + s->length); + if (!direct) + break; + } + if (direct) + ents = dma_direct_map_sg(dev, sg, nents, dir, attrs); + else + ents = ops->map_sg(dev, sg, nents, dir, attrs); + } +#endif else ents = ops->map_sg(dev, sg, nents, dir, attrs); BUG_ON(ents < 0); @@ -207,9 +245,28 @@ void dma_unmap_sg_attrs(struct device *dev, struct scatterlist *sg, BUG_ON(!valid_dma_direction(dir)); debug_dma_unmap_sg(dev, sg, nents, dir); - if (dma_map_direct(dev, ops)) + if (dma_map_direct(dev, ops)) { dma_direct_unmap_sg(dev, sg, nents, dir, attrs); - else if (ops->unmap_sg) + return; + } +#ifdef CONFIG_DMA_OPS_BYPASS_BUS_LIMIT + if (dev->bus_dma_limit) { + struct scatterlist *s; + bool direct = true; + int i; + + for_each_sg(sg, s, nents, i) { + direct = dma_handle_direct(dev, s->dma_address + s->length); + if (!direct) + break; + } + if (direct) { + dma_direct_unmap_sg(dev, sg, nents, dir, attrs); + return; + } + } +#endif + if (ops->unmap_sg) ops->unmap_sg(dev, sg, nents, dir, attrs); } EXPORT_SYMBOL(dma_unmap_sg_attrs); diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index c99de4a21458..02fa174fbdec 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -20,6 +20,10 @@ config DMA_OPS config DMA_OPS_BYPASS bool +# IOMMU driver limited by a DMA window size may switch between bypass and window +config DMA_OPS_BYPASS_BUS_LIMIT + bool + config NEED_SG_DMA_LENGTH bool