RE: [Xen-devel][PATCH] VT-d: Fix PCI-X device assignment

["Han, Weidong" <weidong.han@xxxxxxxxx>]

For PCI-X device, the requester-id "may" come from PCI-X device or its bridge.  
software must consider the possibility of requests arriving with the source-id 
in the original PCI-X transaction or the source-id provided by the bridge. You 
can refer to the 3.6.1.1 Devices Behind PCI Express to PCI/PCI-X Bridges in 
VT-d specification.

BTW, I met DMA page faults when I assigned PCI-X device without my patch.

Regards,
Weidong


Espen Skoglund wrote:
> Hmm... so the bridge does not take ownership of the request coming
> from PCI-X devices?  As far as I remember, this was not my experience
> when I tried mapping a PCI-X device (or does my memory serve me
> wrong?)  I guess different chipsets behaves differently then.  Do you
> know if there is a way to detect how the bridge behaves?  If the
> bridge does not take ownership of the requests then we don't want to
> also map devfn 0 of the bus.
> 
>       eSk
> 
> 
> [Weidong Han]
>> When assign PCI device, current code just map its bridge and its
>> secondary bus number and devfn 0. It doesn't work for PCI-x device
>> assignment, because the request may be the source-id in the original
>> PCI-X transaction or the source-id provided by the bridge. It needs
>> to map the device itself, and its upstream bridges till
>> PCIe-to-PCI/PCI-x bridge.  In addition, add description for
>> DEV_TYPE_PCIe_BRIDGE and DEV_TYPE_PCI_BRIDGE for understandability.
> 
>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel


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