Re: [Xen-devel] [PATCH RFC] p2m: p2m_mmio_direct set RW permissions

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.01.15 at 16:11, <elena.ufimtseva@xxxxxxxxxx> wrote:
> ----- JBeulich@xxxxxxxx wrote:
>> A fundamental question is what business devices have to DMA their
>> own (or other devices') MMIO space. I could remotely see a need
>> for this for e.g. frame buffers, but I have difficulty understanding
>> this for USB devices. Please at the very least provide details on the
>> MMIO regions that those devices have, and which of them you
>> observed IOMMU faults on.
> 
> The IOMMU Page fault addresses are 0xd5d45 and 0xd5d46 in case of 
> ThinkCentre machine.
> If you would like to see any other details I am happy to send them as well.

Yes, the two numbers alone don't tell me anything - I can't even
judge whether they're MFNs, GFNs, or host/guest physical
addresses that way. I also specifically asked for providing the
BAR values of the USB controller in question, to be able to match
up the numbers. Logs and/or lspci output will be most useful for
this purpose.

Jan


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