[libvirt] [RFC PATCH v2 REBASE 00/18] Introduce vGPU mdev framework to libvirt

[Chen, Xiaoguang]

>-----Original Message-----
>From: Erik Skultety [mailto:eskultet at redhat.com]
>Sent: Thursday, March 16, 2017 10:41 PM
>To: Chen, Xiaoguang <xiaoguang.chen at intel.com>
>Cc: libvir-list at redhat.com; He, Yongli <yongli.he at intel.com>
>Subject: Re: [libvirt] [RFC PATCH v2 REBASE 00/18] Introduce vGPU mdev
>framework to libvirt
>
>> [2] 2005
>> ubuntu at z-nuc-11:~/vgpu-meta/libvirt-stage$
>> ***************************************************
>> start libvirt-d
>> 2017-03-09 19:04:57.211+0000: 2059: info : libvirt version: 3.1.0
>> 2017-03-09 19:04:57.211+0000: 2059: info : hostname: z-nuc-11.maas
>> 2017-03-09 19:04:57.211+0000: 2059: error : qemuMonitorOpenUnix:367 :
>> failed to connect to monitor socket: No such process
>> 2017-03-09 19:04:57.213+0000: 2059: error :
>> virMediatedDeviceGetIOMMUGroupDev:153 : internal error: IOMMU group
>> file
>> /sys/bus/mdev/devices/894f3983-1a36-42b3-b52c-
>1024aca216be/iommu_group
>> is not a symlink
>
>When I saw this error message for the first time in the original thread, I got
>confused, since this just checks whether the symlink exists, if it doesn't, the vfio
>device probably also doesn't exist (but take this with a grain of salt, I haven't
>investigated that deep) and libvirt needs it to pass it onto qemu command line. I
>hit this issue once by accident in the past and at that time I didn't understand
>what caused it, but after a reboot it was gone.
>So seeing it here it caught my eye and I investigated it last week. What I found
>out was that it's caused by the vfio-mdev module not being loaded automatically
>as a dependency. I solved it by autoloading the module on system boot. So this is
>not a libvirt issue, but just for a reference, there is a BZ on this [1].
>
>> 2017-03-09 19:04:57.213+0000: 2003: info : libvirt version: 3.1.0
>> 2017-03-09 19:04:57.213+0000: 2003: info : hostname: z-nuc-11.maas
>> 2017-03-09 19:04:57.213+0000: 2003: error : virNetSocketReadWire:1800 :
>> End of file while reading data: Input/output error
>
>I suppose this corresponds to the problem above, do you hit this error if you work
>around the vfio-mdev module problem described above?
Based on the KVMGT setup guide we should add kvmgt, vfio-iommu-type1 and vfio-mdev modules into initfamfs.
So I don't think it is the same problem. But we will double confirm it later. Yong li is on vacation this week when he come back we will do the test again.

>
>>
>> the screen call trace while start the VM (same for Ubuntu, Win10 etc)
>> ======================================================
>>
>> ubuntu at z-nuc-11:~/vgpu-meta/libvirt-stage$ myvirsh start vgpu-ubuntu
>> 2017-03-09 19:06:50.483+0000: 2232: info : libvirt version: 3.1.0
>> 2017-03-09 19:06:50.483+0000: 2232: info : hostname: z-nuc-11.maas
>> 2017-03-09 19:06:50.483+0000: 2232: warning : qemuDomainObjTaint:4056 :
>> Domain id=1 name='vgpu-ubuntu'
>> uuid=972b5e38-0437-11e7-8f97-d36dba74552d
>> is tainted: high-privileges
>> 2017-03-09 19:06:50.819+0000: 2204: info : libvirt version: 3.1.0
>> 2017-03-09 19:06:50.819+0000: 2232: warning :
>> virDomainAuditHostdev:456
>> : Unexpected hostdev type while encoding audit message: 4
>
>This one's interesting, again, are you able to hit the error when you work around
>the missing vfio-mdev module? I'll have a look at this if you actually can hit the
>error, even if the XML is correct.
>
>I posted v3 of the series and also created a new branch 'mdev-next' on my github
>[2]. I dropped the attribute 'type' from the source address element, so follow the
>example in the updated docs.
Will test the v3 when yong li back from vacation.


>
>Thanks for giving it a try.
>Erik
>
>[1] https://bugzilla.redhat.com/show_bug.cgi?id=1420572
>[2] https://github.com/eskultety/libvirt/commits/mdev-next