Re: [Xen-devel] Xen-unstable: AMD-Vi: update_paging_mode Try to access pdev_list without aquiring pcidevs_lock.

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 31/10/2019 10:18, Jan Beulich wrote:
> On 31.10.2019 09:35, Sander Eikelenboom wrote:
>> Platform is perhaps what specific (older AMD 890FX chipset) and I need the 
>> bios workaround:
>> ivrs_ioapic[6]=00:14.0 iommu=on.
> 
> Shouldn't matter here.
> 
>> On the other hand, this has ran like this for quite some time.
>>
>> I have 3 guests (HVM) for which i use PCI passthrough and 
>> for each of those 3 guests I get this message *once* on start of the guest.
>>      One guest has a soundcard passed through,
>>      One guest has a USB2 card passed through,
>>      One guest has a USB3 card passed through.
>>
>> Another observation is that both the soundcard and USB2 card
>> still seem to function despite the message.
> 
> Reality is - this message is benign as long as you don't do PCI
> hot (un)plug.

I don't use any of:
 pci-attach
 pci-detach
 pci-list
 pci-assignable-add
 pci-assignable-remove
 pci-assignable-list

Only shutting down and (re)starting VMs with the devices specified in
the vm cfg file.

>> The USB3 controller goes haywire though (a lot of driver messages in the 
>> guest during init).
> 
> As a consequence I don't think there's a connection between this
> and the observed message.

Ok, although it functions fine when (with same kernel etc. reverting to
the commit I referenced to below), if so, that would be another issue then.

CC'ed Juergen as release manager so he is aware.

>> I could try to bisect, but that would be somewhere next week before I can 
>> get to that.
>>
>> At present I run with a tree with as latest commit 
>> ee7170822f1fc209f33feb47b268bab35541351d,
>> which is stable for me. This predates some of the IOMMU changes and 
>> Anthony's QMP work that had
>> some issues, but that would be the last known real good point for me to 
>> start a bisect from.
> 
> I.e. at that point you didn't observe this message, yet?

With ee7170822f1fc209f33feb47b268bab35541351d, nor this message, nor the
"INVALID_DEV_REQUEST", even with longer uptimes.

--
Sander

> Jan
> 


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