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

[Jürgen Groß]

On 09.11.20 13:00, Jan Beulich wrote:

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?

I wanted to that after this series has been accepted, but I can include
it here, of course.


Juergen

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