Bug 205201 - overflow of DMA mask and bus mask

Thu Nov 7 20:53:10 AEDT 2019

On 05 November 2019 at 5:28 pm, 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
>>
>> 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 at 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 at 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);
>   }
Hello Christoph,

Thanks a lot for your patch! Unfortunately this patch doesn't solve the 
issue.

Error messages:

[    6.041163] bttv: driver version 0.9.19 loaded
[    6.041167] bttv: using 8 buffers with 2080k (520 pages) each for capture
[    6.041559] bttv: Bt8xx card found (0)
[    6.041609] bttv: 0: Bt878 (rev 17) at 1000:04:05.0, irq: 19, 
latency: 128, mmio: 0xc20001000
[    6.041622] bttv: 0: using: Typhoon TView RDS + FM Stereo / KNC1 TV 
Station RDS [card=53,insmod option]
[    6.042216] bttv: 0: tuner type=5
[    6.111994] bttv: 0: audio absent, no audio device found!
[    6.176425] bttv: 0: Setting PLL: 28636363 => 35468950 (needs up to 
100ms)
[    6.200005] bttv: PLL set ok
[    6.209351] bttv: 0: registered device video0
[    6.211576] bttv: 0: registered device vbi0
[    6.214897] bttv: 0: registered device radio0
[  114.218806] bttv 1000:04:05.0: overflow 0x00000000ff507000+4096 of 
DMA mask ffffffff bus mask df000000
[  114.218848] Modules linked in: rfcomm bnep tuner_simple tuner_types 
tea5767 tuner tda7432 tvaudio msp3400 bttv tea575x tveeprom 
videobuf_dma_sg videobuf_core rc_core videodev mc btusb btrtl btbcm 
btintel bluetooth uio_pdrv_genirq uio ecdh_generic ecc
[  114.219012] [c0000001ecddf720] [80000000008ff6e8] 
.buffer_prepare+0x150/0x268 [bttv]
[  114.219029] [c0000001ecddf860] [80000000008fff6c] 
.bttv_qbuf+0x50/0x64 [bttv]

-----

Trace:

[  462.783184] Call Trace:
[  462.783187] [c0000001c6c67420] [c0000000000b3358] 
.report_addr+0xb8/0xc0 (unreliable)
[  462.783192] [c0000001c6c67490] [c0000000000b351c] 
.dma_direct_map_page+0xf0/0x128
[  462.783195] [c0000001c6c67530] [c0000000000b35b0] 
.dma_direct_map_sg+0x5c/0xac
[  462.783205] [c0000001c6c675e0] [8000000000862e88] 
.__videobuf_iolock+0x660/0x6d8 [videobuf_dma_sg]
[  462.783220] [c0000001c6c676b0] [8000000000854274] 
.videobuf_iolock+0x98/0xb4 [videobuf_core]
[  462.783271] [c0000001c6c67720] [80000000008686e8] 
.buffer_prepare+0x150/0x268 [bttv]
[  462.783276] [c0000001c6c677c0] [8000000000854afc] 
.videobuf_qbuf+0x2b8/0x428 [videobuf_core]
[  462.783288] [c0000001c6c67860] [8000000000868f6c] 
.bttv_qbuf+0x50/0x64 [bttv]
[  462.783383] [c0000001c6c678e0] [80000000007bf208] .v4l_qbuf+0x54/0x60 
[videodev]
[  462.783402] [c0000001c6c67970] [80000000007c1eac] 
.__video_do_ioctl+0x30c/0x3f8 [videodev]
[  462.783421] [c0000001c6c67a80] [80000000007c3c08] 
.video_usercopy+0x18c/0x3dc [videodev]
[  462.783440] [c0000001c6c67c00] [80000000007bb14c] 
.v4l2_ioctl+0x60/0x78 [videodev]
[  462.783460] [c0000001c6c67c90] [80000000007d3c48] 
.v4l2_compat_ioctl32+0x9b4/0x1850 [videodev]
[  462.783468] [c0000001c6c67d70] [c0000000001ad9cc] 
.__se_compat_sys_ioctl+0x284/0x127c
[  462.783473] [c0000001c6c67e20] [c00000000000067c] system_call+0x60/0x6c
[  462.783475] Instruction dump:
[  462.783477] 40fe0044 60000000 892255d0 2f890000 40fe0020 3c82ffc5 
39200001 60000000
[  462.783483] 38842029 992255d0 485ad0d9 60000000 <0fe00000> 38210070 
e8010010 7c0803a6
[  462.783490] ---[ end trace b677d4a00458e277 ]---

-----

dmesg fsl p5040: https://bugzilla.kernel.org/attachment.cgi?id=285813

Kernel 5.4-rc6 config for the Cyrus+ board and for the QEMU ppce500 
board (CPU: P5040 and P5020): 
https://bugzilla.kernel.org/attachment.cgi?id=285815

Bug report: https://bugzilla.kernel.org/show_bug.cgi?id=205201

Thanks for your help,

Christian