Comment 11 for bug 1867519

I regularly before a release pull in fixes that were posted for qemu-stable.
This is one of them, I'll again do such a build and retest this issue with it.

I identified and backported (only one needed modification) 33 patches.
But as usual there might be some context needed on top - I have build that over night in [1]

Testing that on my reproducer

Attach-host:
[84652.671123] vfio-pci 0000:08:00.2: enabling device (0000 -> 0002)

Attach-guest:
[ 45.199920] pci 0000:00:08.0: [15b3:1016] type 00 class 0x020000
[ 45.200374] pci 0000:00:08.0: reg 0x10: [mem 0x00000000-0x000fffff 64bit pref]
[ 45.201358] pci 0000:00:08.0: enabling Extended Tags
[ 45.202726] pci 0000:00:08.0: 0.000 Gb/s available PCIe bandwidth, limited by Unknown speed x0 link at 0000:00:08.0 (capable of 63.008 Gb/s with 8 GT/s x8 link)
[ 45.208316] pci 0000:00:08.0: BAR 0: assigned [mem 0x100000000-0x1000fffff 64bit pref]
[ 45.256566] mlx5_core 0000:00:08.0: enabling device (0000 -> 0002)
[ 45.262103] mlx5_core 0000:00:08.0: firmware version: 14.27.1016
[ 45.544010] mlx5_core 0000:00:08.0: MLX5E: StrdRq(0) RqSz(1024) StrdSz(256) RxCqeCmprss(0)
[ 45.710123] mlx5_core 0000:00:08.0 ens8: renamed from eth0
[ 60.992547] random: crng init done
[ 60.992552] random: 3 urandom warning(s) missed due to ratelimiting

Detach-host:
[84926.767411] mlx5_core 0000:08:00.2: enabling device (0000 -> 0002)
[84926.767514] mlx5_core 0000:08:00.2: firmware version: 14.27.1016
[84927.036146] mlx5_core 0000:08:00.2: MLX5E: StrdRq(0) RqSz(1024) StrdSz(256) RxCqeCmprss(0)
[84927.208523] mlx5_core 0000:08:00.2 ens1v1: renamed from eth0

Detach-guest:
<nothing>

So yes, these changes fix the issue here (and a bunch of others).
I'll open up an MP to get these changes into Ubuntu 20.04.

[1]: https://launchpad.net/~ci-train-ppa-service/+archive/ubuntu/3981