control/shutdown node removed on suspend?

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

Hi,

I've just got an interesting bug report - it seems Windows PV drivers (or
something else?) remove control/shutdown xenstore node on suspend,
instead of just writing empty string there (to ack the request).
This makes subsequent suspend to fail, because toolstack does not adjust
permissions of that node when writing to it (assuming it was set
correctly during domain construction), which means domU has no longer
write access to it and cannot acknowledge the request.

TBH, I'm not sure where exactly this happens, could be also outside of
PV drivers. But the issue doesn't apply for Linux VMs - that's why I
think it is related to Windows PV drivers.
https://xenbits.xen.org/gitweb/?p=pvdrivers/win/xeniface.git;a=blob;f=src/xenagent/service.cpp;h=9bc5c20767454eaeae4760308d7655580a08e4cb;hb=5c6adcaa423c465de279158c4cc42500627c20a0
seems to use StoreWrite("control/shutdown", ""), which sounds correct
(if it really does what it suggests to do). But that's just cursory look
at the code, I'm not sure if that's even the correct file.

The system is using official build of 8.2.2 drivers.

Original bug report can be found here:
https://github.com/QubesOS/qubes-issues/issues/7404#issuecomment-1117231111
(see subsequent comments for details)

Any idea?

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

Attachment: signature.asc
Description: PGP signature