Sorry to email directly but I've tried reportbug but it doesn't seem to
work with the kernel packages.
The 5.6.0-1 kernel in Sid when used in conjunction with VFIO (PCI
passthrough) guests in Qemu-KVM causes KVM to crash with no useful logs
- the guest partially starts. Eventually the host slows down and needs
to be powered off. Doesn't affect non-VFIO guests using spice/headless,
only when passing through a PCIe graphics card or USB keyboard/mouse.
5.6.0-2 that just landed makes this infinitely worse - as soon as you
start a VFIO guest the host hard crashes.
5.3/5.4/5.5 kernels do not have this problem with the same version of
Qemu and reverting from qemu 5.0 to 4.2 doesn't help, so it must be the
5.6 kernel causing the issue.
Not sure what logs or any useful information I can supply you, there's
some interesting comments on this reddit thread suggesting a couple of
bugs that have fixes upstream:
https://www.reddit.com/r/VFIO/comments/glfgqs/qemu_5_vfio_no_longer_works_on_debian/
I'm using macos catalina and win10 guests to reproduce the issue, and
using Intel not AMD chips.
Cheers.
--
Simon John
