[Xen-devel] panic("queue invalidate wait descriptor was not executed\n")

["Zytaruk, Kelly" <Kelly.Zytaruk@xxxxxxx>]

During Xen boot I am seeing the panic in the subject line from 
.../xen/drivers/passthrough/vgt/qinval.c

From the Fault Status Register (= 0x40 (ITE)). I am seeing a hardware timeout 
on the invalidate

Disabling queued invalidation is not an option.  I need to find out why the 
operation is timing out and fix it.  

I found two timeouts; one in software and one in hardware. 
After the invalidate is submitted there is a wait packet submitted and the boot 
software waits for the wait packet to complete in a loop with a software 
timeout.  At the end of the software timeout it issues the panic.  I can 
increase the software timeout but it still doesn't solve the problem.  Just 
before the panic I dump the value of the Fault Status Register and I see that 
the hardware has already timed out (FSTS_REG = 0x40 = ITE = "Invalidation 
Timeout Error").  As a first step in solving this I would like to increase the 
hardware timeout value.

I have the Intel spec and I was reading from the spec...

" Hardware starts an invalidation completion timer for this ITag, and issues 
the invalidation request message to the specified endpoint. If the invalidation 
command from software is for a first-level mapping, the invalidation request 
message is generated with the appropriate PASID prefix to identify the target 
PASID. The invalidation completion time-out value is recommended to be 
sufficiently larger than the PCI-Express read completion time-outs. "

The above leads me to believe that there should be some way of setting the 
invalidation completion time-out value.  Unfortunately I couldn't find anything 
in the Intel spec that tells me how to set the "invalidation completion 
time-out".   Can someone point me in the right direction to setting the 
completion timer?

Thanks,
Kelly

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