[Xen-devel] RE: [PATCH] xend: passthrough: check if a device is behind PCIe switch that lacks ACS

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

Attached patch fixes following xend error caused by the ACS patch.

Signed-off-by: Allen Kay <allen.m.kay@xxxxxxxxx>

===========

xend start
Traceback (most recent call last):
  File "/usr/sbin/xend", line 36, in <module>
    from xen.xend.server import SrvDaemon
  File "usr/lib64/python2.5/site-packages/xen/xend/server/SrvDaemon.py", line 
26, in <module>
  File "usr/lib64/python2.5/site-packages/xen/xend/server/relocate.py", line 
28, in <module>
  File "usr/lib64/python2.5/site-packages/xen/xend/XendDomain.py", line 35, in 
<module>
  File "usr/lib64/python2.5/site-packages/xen/xend/XendCheckpoint.py", line 23, 
in <module>
  File "usr/lib64/python2.5/site-packages/xen/xend/XendConfig.py", line 28, in 
<module>
  File "usr/lib64/python2.5/site-packages/xen/xend/XendPPCI.py", line 23, in 
<module>
  File "/usr/lib64/python2.5/site-packages/xen/util/pci.py", line 1006
    PCI_EXT_CAP_ACS_ENABLED
                          ^
SyntaxError: invalid syntax



-----Original Message-----
From: Cui, Dexuan 
Sent: Tuesday, August 18, 2009 7:27 PM
To: Keir Fraser; xen-devel@xxxxxxxxxxxxxxxxxxx
Cc: Kay, Allen M
Subject: [PATCH] xend: passthrough: check if a device is behind PCIe switch 
that lacks ACS

Imagine a PCIe switch, which doesn't support ACS (Access Control Services),
has 2 downstream ports: A and B, according to PCIe spec, the PCIe switch
should directly route the transaction that is from A and to a device under
B -- the Root Complex and IOMMU engine are bypassed -- this doesn't work at
all in the case of hvm guest and can even incur potential security issue, so
we should not allow such kind of device assignment.

If all the intermediate PCIe swiches between a device and Root Complex support
and enable ACS, we can safely asssign the device to guest.
Allen Kay will enable ACS later.

Thanks,
-- Dexuan

Attachment: xend_acs_fix.patch
Description: xend_acs_fix.patch

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