From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: [PATCH 1/7] core, dma-direct: add a flag 32-bit dma limits Date: Fri, 25 May 2018 16:35:06 +0200 Message-ID: <20180525143512.1466-2-hch@lst.de> References: <20180525143512.1466-1-hch@lst.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-ia64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Thomas Gleixner , Ingo Molnar , Tony Luck , Fenghua Yu , Greg Kroah-Hartman Return-path: In-Reply-To: <20180525143512.1466-1-hch-jcswGhMUV9g@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: netdev.vger.kernel.org Various PCI bridges (VIA PCI, Xilinx PCIe) limit DMA to only 32-bits even if the device itself supports more. Add a single bit flag to struct device (to be moved into the dma extension once we around it) to flag such devices and reject larger DMA to them. Signed-off-by: Christoph Hellwig --- include/linux/device.h | 3 +++ lib/dma-direct.c | 6 ++++++ 2 files changed, 9 insertions(+) diff --git a/include/linux/device.h b/include/linux/device.h index 477956990f5e..fa317e45f5e6 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -904,6 +904,8 @@ struct dev_links_info { * @offline: Set after successful invocation of bus type's .offline(). * @of_node_reused: Set if the device-tree node is shared with an ancestor * device. + * @dma_32bit_limit: bridge limited to 32bit DMA even if the device itself + * indicates support for a higher limit in the dma_mask field. * * At the lowest level, every device in a Linux system is represented by an * instance of struct device. The device structure contains the information @@ -992,6 +994,7 @@ struct device { bool offline_disabled:1; bool offline:1; bool of_node_reused:1; + bool dma_32bit_limit:1; }; static inline struct device *kobj_to_dev(struct kobject *kobj) diff --git a/lib/dma-direct.c b/lib/dma-direct.c index bbfb229aa067..0151a7b2bc87 100644 --- a/lib/dma-direct.c +++ b/lib/dma-direct.c @@ -165,6 +165,12 @@ int dma_direct_supported(struct device *dev, u64 mask) if (mask < DMA_BIT_MASK(32)) return 0; #endif + /* + * Various PCI/PCIe bridges have broken support for > 32bit DMA even + * if the device itself might support it. + */ + if (dev->dma_32bit_limit && mask > DMA_BIT_MASK(32)) + return 0; return 1; } -- 2.17.0