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

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

Tom Rotenberg wrote:
> Well, you are correct... however, the situation is that the bgefore
> the disable the intx bit was turned off, and only after disable and
> then re-enable it was turned on, and that's the strange part of it...

You mean even if the msi_translate == 0? That's strange. If this happens only 
under msi_translate, it is reasonable and maybe something wrong. So can you 
give me a confirmation?

--jyh

> 
> On Wed, Nov 25, 2009 at 11:38 AM, Jiang, Yunhong
> <yunhong.jiang@xxxxxxxxx> wrote:
>> If the msi_translate=0, why IntX bit is turned on is wrong?
> I assume guest should use intX in such situation.
>> 
>> --jyh
>> ________________________________________
>> From: Tom Rotenberg [tom.rotenberg@xxxxxxxxx]
>> Sent: Wednesday, November 25, 2009 2:29 AM
>> To: Jiang, Yunhong
>> Cc: Kamala Narasimhan; xen-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: Re: [Xen-devel] Bug when disabling/enabling a PT device
>> with MSI       enabled 
>> 
>> 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
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>>> http://lists.xensource.com/xen-devel
>>> 
>>> _______________________________________________
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