Messages in this thread | | | Subject | Re: Bug 205201 - overflow of DMA mask and bus mask | From | Robin Murphy <> | Date | Wed, 6 Nov 2019 14:09:26 +0000 |
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On 05/11/2019 16:28, Christoph Hellwig wrote: > 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
Hmm, that bus mask looks pretty wacky - are you able to figure out where that's coming from?
Robin.
>> 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@suse.de> > 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@suse.de> > --- > 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); > } >
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