RE: [Xen-devel] Bug when disabling/enabling a PT device with MSI enabled

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

This should be about qemu's MSI support. The code is in qemu/hw/pt-msi.c for 
all MSI emulation. 
Windows XP does not support MSI if I remember correctly. SO this issue should 
be about MSI translation, i.e. guest is using IOAPIC while host is using MSI. 
Xen hypervisor will translate the MSI to guest's IOAPIC. 

--jyh
________________________________________
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
[xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tom Rotenberg 
[tom.rotenberg@xxxxxxxxx]
Sent: Wednesday, November 25, 2009 1:27 AM
To: Kamala Narasimhan
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Bug when disabling/enabling a PT device with MSI       
enabled

Well, just tested it with the 2.6.18 latest kernel, and the bug still exists.
Also, i think that iit's more related to how qemu handles the
"disable/enable" of domU for PT devices with MSI... but i don't know
where to start from? it looks like when re-enabling a PT device with
MSI, we need qemu to re-initialize the device according to it's
original MSI state (and not to what it was resetted before).

Does anyone has any clue about it?

On Wed, Nov 25, 2009 at 4:25 AM, Kamala Narasimhan
<Kamala.Narasimhan@xxxxxxxxxx> wrote:
>
> Couple of questions -
>
> 1) What kind of device are you referring to below?  Display by any chance?
> 2) Which tree is your dom0 kernel based on?
>
> There is a chance you are missing some msi patches in your dom0 kernel.  You 
> might want to do a quick search for msi patches in 
> http://xenbits.xen.org/staging/linux-2.6.18-xen.hg?rev=msi and see if you are 
> missing anything obvious.  I recently encountered a similar issue in a 
> slightly different situation, a subset of the problem was caused because of 
> missing msi patches.
>
> Kamala
>
>> -----Original Message-----
>> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
>> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tom Rotenberg
>> Sent: Tuesday, November 24, 2009 1:43 PM
>> To: xen-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: [Xen-devel] Bug when disabling/enabling a PT device with MSI
>> enabled
>>
>> Hi,
>>
>> I am using the xen-3,4, and i am doing pass-through for a device with
>> MSI enabled (the device of-course supports MSI) to a domU with Windows
>> XP. When i disable and then re-enable the device using Windows device
>> manager, everything looks like it's working fine, but the device seems
>> to malfunction.
>> After digging a little bit, i saw that the problem is, because the bit
>> of the interrupt-status (bit 3) in the status register (offset 0x6 in
>> the PCI config space) was turned on somehow -  this proibably caused
>> the MSI to malfunction (because the IntX assertion was enabled - thus
>> disabling the MSI) - and this lead to the problem i experienced.
>>
>> Any ideas on how to solve this issue?
>>
>> Tom
>>
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>

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