[Qemu-devel] Re: kvm crashes with spice while loading qxl

[xming]

Oops forgot to send this to the list too, here we go

> That's a spice bug. In fact, there are a lot of
> qemu_mutex_lock/unlock_iothread in that subsystem. I bet at least a few
> of them can cause even more subtle problems.

Just tried spice 0.7.3 (was using 0.6.x) and still the same, should I
file a bug against spice?

> Two general issues with dropping the global mutex like this:
>  - The caller of mutex_unlock is responsible for maintaining
>   cpu_single_env across the unlocked phase (that's related to the
>   abort above).
>  - Dropping the lock in the middle of a callback is risky. That may
>   enable re-entrances of code sections that weren't designed for this
>   (I'm skeptic about the side effects of
>   qemu_spice_vm_change_state_handler - why dropping the lock here?).
>
> Spice requires a careful review regarding such issues. Or it should
> pioneer with introducing its own lock so that we can handle at least
> related I/O activities over the VCPUs without holding the global mutex
> (but I bet it's not the simplest candidate for such a new scheme).
>
> Jan