On Tue, Nov 05, 2019 at 08:56:27AM +0100, Christian Zigotzky wrote: > Hi All, > > We still have DMA problems with some PCI devices. Since the PowerPC updates > 4.21-1 [1] we need to decrease the RAM to 3500MB (mem=3500M) if we want to > work with our PCI devices. The FSL P5020 and P5040 have these problems > currently. > > Error message: > > [ 25.654852] bttv 1000:04:05.0: overflow 0x00000000fe077000+4096 of DMA > mask ffffffff bus mask df000000 > > All 5.x Linux kernels can't initialize a SCSI PCI card anymore so booting > of a Linux userland isn't possible. > > PLEASE check the DMA changes in the PowerPC updates 4.21-1 [1]. The kernel > 4.20 works with all PCI devices without limitation of RAM. Can you send me the .config and a dmesg? And in the meantime try the patch below? --- >From 4d659b7311bd4141fdd3eeeb80fa2d7602ea01d4 Mon Sep 17 00:00:00 2001 From: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> Date: Fri, 18 Oct 2019 13:00:43 +0200 Subject: dma-direct: check for overflows on 32 bit DMA addresses As seen on the new Raspberry Pi 4 and sta2x11's DMA implementation it is possible for a device configured with 32 bit DMA addresses and a partial DMA mapping located at the end of the address space to overflow. It happens when a higher physical address, not DMAable, is translated to it's DMA counterpart. For example the Raspberry Pi 4, configurable up to 4 GB of memory, has an interconnect capable of addressing the lower 1 GB of physical memory with a DMA offset of 0xc0000000. It transpires that, any attempt to translate physical addresses higher than the first GB will result in an overflow which dma_capable() can't detect as it only checks for addresses bigger then the maximum allowed DMA address. Fix this by verifying in dma_capable() if the DMA address range provided is at any point lower than the minimum possible DMA address on the bus. Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx> --- include/linux/dma-direct.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h index adf993a3bd58..6ad9e9ea7564 100644 --- a/include/linux/dma-direct.h +++ b/include/linux/dma-direct.h @@ -3,6 +3,7 @@ #define _LINUX_DMA_DIRECT_H 1 #include <linux/dma-mapping.h> +#include <linux/memblock.h> /* for min_low_pfn */ #include <linux/mem_encrypt.h> #ifdef CONFIG_ARCH_HAS_PHYS_TO_DMA @@ -27,6 +28,13 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size) if (!dev->dma_mask) return false; +#ifndef CONFIG_ARCH_DMA_ADDR_T_64BIT + /* Check if DMA address overflowed */ + if (min(addr, addr + size - 1) < + __phys_to_dma(dev, (phys_addr_t)(min_low_pfn << PAGE_SHIFT))) + return false; +#endif + return addr + size - 1 <= min_not_zero(*dev->dma_mask, dev->bus_dma_mask); } -- 2.20.1
