5.6 kernel crashes host when using VFIO on KVM guests

From	Simon John <debian@the-jedi.co.uk>
Newsgroups	linux.debian.kernel
Subject	5.6 kernel crashes host when using VFIO on KVM guests
Date	2020-05-25 22:40 +0200
Message-ID	<Aas37-1ux-7@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

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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

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5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-05-25 22:40 +0200
  Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Salvatore Bonaccorso <carnil@debian.org> - 2020-05-27 21:40 +0200
    Processed: Re: 5.6 kernel crashes host when using VFIO on KVM guests "Debian Bug Tracking System" <owner@bugs.debian.org> - 2020-05-27 21:40 +0200
    Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-05-27 22:50 +0200
      Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-06-12 00:30 +0200
        Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-06-14 00:50 +0200
          Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-06-28 02:00 +0200
            Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-06-28 02:10 +0200
              Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Salvatore Bonaccorso <carnil@debian.org> - 2020-06-28 10:50 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <simon@the-jedi.co.uk> - 2020-06-28 12:10 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-07-03 23:50 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-07-19 00:20 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-07-19 01:40 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-07-19 01:50 +0200
                Bug#961676: 5.6 kernel crashes host when using VFIO on KVM guests Simon John <debian@the-jedi.co.uk> - 2020-07-19 18:00 +0200
    Bug#961676: marked as done (5.6 kernel crashes host when using  VFIO on KVM guests) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2020-07-19 18:20 +0200

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