Live Migration with GVT-g (mdev) passthrough device?

[n1nj4888]

Hi There,

I currently have a 2-node Proxmox 6.1 cluster (3rd node is qdevice) where both nodes are the same hardware spec and support Intel GVT-g (mediated device) Passthrough.

I know live migration between nodes is not possible with standard GPU device Passthrough but, if GVT-g enables the presentation of a “virtual GPU” to the VM, is there anyway of replicating the state of this GVT-g mediated device between nodes to enable live migration of such a VM with GVT-g Passthrough?

thanks!

 

[wolfgang]

Hi,

a precondition for it is a kernel >= 5.4.

 

[n1nj4888]

Ok thanks. So sounds like it is theoretically possible, just that we have to wait until PVE updates to kernel 5.4+?

 

[dcsapak]

afaics, there is still support missing in the upstream kernel (even 5.6)
at least i cannot find anything from this news post https://phoronix.com/scan.php?page=news_item&px=Intel-GVT-g-Live-Migration-QEMU
in the upstream kernel repository...

also i do not see anything related to this in the qemu master branch...

 

[n1nj4888]

Hi @dcsapak,

Are there any specific URLs you can share where I could check the status of this exciting feature?

I’ve posted the same question at the phoronix article above but that article is 1yr old now...

Thanks!

 

[dcsapak]

Are there any specific URLs you can share where I could check the status of this exciting feature?

not that i am aware of, but you can search on the kernel, kvm and qemu mailing lists

 

[n1nj4888]

Just following up on this, looks like the qemu patches have been applied to qemu v5.2 and kernel patches are work in progress - https://github.com/intel/gvt-linux/issues/175#issuecomment-792516421

 

[dcsapak]

as soon as there are released kernels with that working, we can look into that, but not sooner.
also it may take longer since this will probably not work on every hardware, so we'll have to see if we have the hardware to test this out

 

[telvenes]

update?

 

[codgician]

It seems to be still missing in mainline as of today. I doubt this will ever happen since the latest intel gpus are switching to SR-IOV based solutions instead of GVT-g.