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

[Tom Rotenberg <tom.rotenberg@xxxxxxxxx>]

Well, to try and see if the problem is msi related or not, i
registered the device with the option of 'msi_translate=0' to force
the use of intx instead of MSI, and i still got the problem... so i
guess it's not related to the MSI.

It looks like the IntX bit (bit 3 of status word) is runed on somehow
outside qemu, and that's the problem... could that be?

On Wed, Nov 25, 2009 at 11:17 AM, Jiang, Yunhong
<yunhong.jiang@xxxxxxxxx> wrote:
> Sorry send out the mail too quickly.
> I realized it is MSI translation when I finished first section but forgot 
> remove it, so please ignore  first section.
> You only need care about MSI translation, the code is in hw/pass-through.c. 
>  You can check qemu's changelog at a8d1bd66.
>
> --jyh
> ________________________________________
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Jiang, Yunhong 
> [yunhong.jiang@xxxxxxxxx]
> Sent: Wednesday, November 25, 2009 2:10 AM
> To: Tom Rotenberg; Kamala Narasimhan
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] Bug when disabling/enabling a PT device with MSI     
>   enabled
>
> 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
>>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel