Bug 205201 - overflow of DMA mask and bus mask

Mon Nov 11 19:12:10 AEDT 2019

On 10 November 2019 at 08:27 am, Christian Zigotzky wrote:
> On 07 November 2019 at 10:53 am, Christian Zigotzky wrote:
>> On 05 November 2019 at 05:28 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
>
> Christoph,
>
> Do you have another patch for testing or shall I bisect?
>
> Thanks,
> Christian

Hi Christoph,

I have seen that I have activated the kernel config option 
CONFIG_ARCH_DMA_ADDR_T_64BIT. That means your code in your patch won't 
work if this kernel option is enabled.

+#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

I will delete the lines with ifndef and endif and will try it again.

Cheers,
Christian