Re: [Xen-devel] Issue about domU missing interrupt

["G.R." <firemeteor@xxxxxxxxxxxxxxxxxxxxx>]

> I had a quick look, and it doesn't look that hard to backport that patch.

Thanks, Mat.
I'm glad to report that the patch do fix my problem.

And yest it is really easy to port since the code did not change across the two release.
The only change would be line numbers (3841 vs 3803) and one extra comments before this line:
 static int pt_msix_update_one(struct pt_dev *dev, int entry_nr)
I'm not sure if you are going to release another maintenance version that include this patch,
but I'll report this to Debain maintainer since it's about to freeze for v7.0 release and v4.2.0 will not make it.

On Mon, Dec 3, 2012 at 9:58 PM, Mats Petersson <mats.petersson@xxxxxxxxxx> wrote:

On 03/12/12 13:19, Mats Petersson wrote:

On 03/12/12 13:14, G.R. wrote:

On Mon, Dec 3, 2012 at 6:15 PM, Mats Petersson
<mats.petersson@xxxxxxxxxx <mailto:mats.petersson@citrix.com>> wrote:

     On 03/12/12 03:47, G.R. wrote:

         Hi developers,
         I met some domU issues and the log suggests missing interrupt.
         Details from here:
         http://www.gossamer-threads.com/lists/xen/users/263938#263938
         In summary, this is the suspicious log:

         (XEN) vmsi.c:122:d32767 Unsupported delivery mode 3

         I've checked the code in question and found that mode 3 is an
         'reserved_1' mode.
         I want to trace down the source of this mode setting to
         root-cause the issue.
         But I'm not an xen developer, and am even a newbie as a xen user.
         Could anybody give me instructions about how to enable
         detailed debug log?
         It could be better if I can get advice about experiments to
         perform / switches to try out etc.

         My SW config:
         dom0: Debian wheezy (3.6 experimental kernel, xen 4.1.3-4)
         domU: Debian wheezy 3.2.x stock kernel.

         Thanks,
         Timothy

     Are you passing hardware (PCI Passthrough) to the HVM guest?
     What are the exact messages in the DomU?


Yes, I'm doing PCI passthrough (the IGD, audio && USB controller).
But this is actually a PVHVM guest since debian stock kernel has PVOP
enabled.
And when I tried another PVOP disabled linux distro (openelec v2.0), I
did not see such msi related error message.
Actually, with that domU I do not see anything obvious wrong from the
log, but I also see nothing from panel (panel receive no signal and go
power-saving) :-(


Back to the issue I was reporting, the domU log looks like this:

Dec 2 21:52:44 debvm kernel: [ 1085.604071]
[drm:i915_hangcheck_ring_idle]
*ERROR* Hangcheck timer elapsed... blt ring idle [waiting on 3354, at
3354], missed IRQ?
Dec 2 21:56:50 debvm kernel: [ 1332.076071]
[drm:i915_hangcheck_ring_idle]
*ERROR* Hangcheck timer elapsed... render ring idle [waiting on 11297, at
11297], missed IRQ?
Dec 2 22:32:48 debvm kernel: [ 7.220073] hda-intel: azx_get_response
timeout, switching to polling mode: last cmd=0x000f0000
Dec 2 22:45:32 debvm kernel: [ 776.392084] hda-intel: No response from
codec, disabling MSI: last cmd=0x002f0600
Dec 2 22:45:33 debvm kernel: [ 777.400075] hda_intel: azx_get_response
timeout, switching to single_cmd mode: last cmd=0x002f0600


Thanks,
Timothy

It does sound like there is a fix in 4.2.0, as indicated by Jan, that
fixes this. I'm not fully clued up to what the policy for backporting
fixes are, and I haven't looked at the complexity of the fix itself, but
either updating to the 4.2.0 or a (personal) backport sounds like the
right solution here.

I had a quick look, and it doesn't look that hard to backport that patch.

--
Mats

Unfortunately, I hadn't seen Jan's reply by the time I wrote my response
to your original email.

--
Mats

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