[Qemu-devel] [Bug 1671677] [NEW] vfio-pci passthrough issue after resume from suspend

[Max Ehrlich]

Public bug reported:


I'm running into a weird issue with the vfio-pci driver through qemu

I use it on a laptop and I passthrough an external GPU connected via PCI
express. In general this works well, however if the laptop has *ever*
suspended since its last boot, then the windows guest reports an error
43 on the card and I get no output on the monitor that it is connected
to. This is really weird to me since it works fine if I boot the latop
from power-off, and hotplug the card. It's only if the laptop has ever
suspended since it's last boot that I see this issue. Even if it was
suspended before the card was ever hotplugged.

In other words:
laptop off -> boot -> hotplug GPU : works great
laptop off -> boot -> do stuff (GPU *NOT* connected) -> sleep -> resume -> 
hotplug GPU: problem
laptop off -> boot -> hotplug GPU -> unplug GPU -> hotplug GPU : works great
laptop off -> boot -> hotplug GPU -> unplug GPU -> sleep -> resume -> hotplug 
GPU: problem

Weird stuff...

I'm honestly not sure that vfio-pci/qemu is to blame here since there
are so many moving parts, but im not really sure where else to report
this to

What I have tried is using the sysfs interface to
remove/rescan/poweroff/etc the PCI devices in questions (graphics card
and it's HDMI audio) and this also does help.

QEMU version: 2.6.1

Please let me know what other information I can provide

** Affects: qemu
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1671677

Title:
  vfio-pci passthrough issue after resume from suspend

Status in QEMU:
  New

Bug description:
  
  I'm running into a weird issue with the vfio-pci driver through qemu

  I use it on a laptop and I passthrough an external GPU connected via
  PCI express. In general this works well, however if the laptop has
  *ever* suspended since its last boot, then the windows guest reports
  an error 43 on the card and I get no output on the monitor that it is
  connected to. This is really weird to me since it works fine if I boot
  the latop from power-off, and hotplug the card. It's only if the
  laptop has ever suspended since it's last boot that I see this issue.
  Even if it was suspended before the card was ever hotplugged.

  In other words:
  laptop off -> boot -> hotplug GPU : works great
  laptop off -> boot -> do stuff (GPU *NOT* connected) -> sleep -> resume -> 
hotplug GPU: problem
  laptop off -> boot -> hotplug GPU -> unplug GPU -> hotplug GPU : works great
  laptop off -> boot -> hotplug GPU -> unplug GPU -> sleep -> resume -> hotplug 
GPU: problem

  Weird stuff...

  I'm honestly not sure that vfio-pci/qemu is to blame here since there
  are so many moving parts, but im not really sure where else to report
  this to

  What I have tried is using the sysfs interface to
  remove/rescan/poweroff/etc the PCI devices in questions (graphics card
  and it's HDMI audio) and this also does help.

  QEMU version: 2.6.1

  Please let me know what other information I can provide

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