Re: [Qemu-devel] [PATCH] pci: add standard bridge device

[Wen Congyang]

At 08/22/2011 02:23 PM, Avi Kivity Write:
> On 08/22/2011 06:13 AM, Wen Congyang wrote:
>> At 08/19/2011 11:26 PM, Avi Kivity Write:
>> >  On 08/18/2011 10:12 PM, Wen Congyang wrote:
>> >>  >>
>> >>  >>   The following patch can fix this problem, but I'm not sure
>> whether it
>> >>  >>   is right.
>> >>  >
>> >>  >   It's correct but insufficient, the filtering code
>> (pci_bridge_filter)
>> >>  >   needs to be updated to use the memory API.
>> >>
>> >>  I read the function pci_bridge_filter(), and the function only read
>> >>  PCI bridge's config space(command, base and limit). If base>   limit,
>> >>  it will set addr to PCI_BAR_UNMAPPED.
>> >>
>> >>  I do not find anything that needs to updated to use the memory API.
>> >
>> >  Currently it doesn't do any filtering at all.  Bridges need to
>> create a
>> >  new address space, then attach aliases of this region
>> (corresponding to
>> >  the filtered area and to the legacy vga space) to the parent bus'
>> >  address space.
>>
>> Hmm, does this problem exist before memory API is introduced?
> 
> Yes.  There was code to handle it, but I don't think it was correct.
> 
>>
>> >
>> >>  I add a scsi controller on pci bus1, and a scsi disk on this
>> controller.
>> >>  I can read and write this disk, and I do not meet any problem.
>> >>
>> >
>> >  However, filtering doesn't work.  You could put a BAR outside the
>> >  filtered area and it would be visible to the guest.
>>
>> How to put a BAR outside the filtered area and confirm whether it
>> would be
>> virible to the guest?
>>
>>
> 
> 
> You could use something like kvm-unit-tests.git to write a simple test
> that sets up a BAR (say from hw/ivshmem.c), writes and reads to see that
> it is visible, programs the bridge to filter part of the BAR out, then
> writes and reads again to verify that the correct part is filtered out.

I am testing ivshmem now. But I do not know how to access the memory
specified in the BAR.

Thanks
Wen Congyang

>