[Qemu-devel] virtio device error reporting best practice?

[Dave Airlie]

So I'm looking at how best to do virtio gpu device error reporting,
and how to deal with illegal stuff,

I've two levels of errors I want to support,

a) unrecoverable or bad guest kernel programming errors,

b) per 3D context errors from the renderer backend,

(b) I can easily report in an event queue and the guest kernel can in
theory blow away the offenders, this is how GL works with some
extensions,

For (a) I can expect a response from every command I put into the main
GPU control queue, the response should always be no error, but in some
cases it will be because the guest hit some host resource error, or
asked for something insane, (guest kernel drivers would be broken in
most of these cases).

Alternately I can use the separate event queue to send async errors
when the guest does something bad,

I'm also considering adding some sort of flag in config space saying
the device needs a reset before it will continue doing anything,

The main reason I'm considering this stuff is for security reasons if
the guest asks for something really illegal or crazy what should the
expected behaviour of the host be? (at least secure I know that).

Dave.