Re: [PATCH v5 0/2] XSA-343 followup patches

[Jan Beulich <jbeulich@xxxxxxxx>]

On 09.11.2020 07:41, Juergen Gross wrote:
> The patches for XSA-343 produced some fallout, especially the event
> channel locking has shown to be problematic.
> 
> Patch 1 is targeting fifo event channels for avoiding any races for the
> case that the fifo queue has been changed for a specific event channel.
> 
> The second patch is modifying the per event channel locking scheme in
> order to avoid deadlocks and problems due to the event channel lock
> having been changed to require IRQs off by the XSA-343 patches.
> 
> Changes in V5:
> - moved evtchn_write_[un]lock() to event_channel.c (Jan Beulich)
> - used normal read_lock() in some cases (Jan Beulich)
> 
> Changes in V4:
> - switched to real rwlock
> 
> Changes in V3:
> - addressed comments
> 
> Juergen Gross (2):
>   xen/events: access last_priority and last_vcpu_id together
>   xen/evtchn: rework per event channel lock

Didn't you mean to add a 3rd patch here to drop the 2nd call to
xsm_evtchn_send() again?

Jan