Re: [PATCH 2/8] xen/evtchn: modify evtchn_alloc_unbound to allocate specified port

[Julien Grall <julien@xxxxxxx>]

Hi,

On 22/06/2022 15:37, Rahul Singh wrote:
> evtchn_alloc_unbound() always allocates the next available port. Static
> event channel support for dom0less domains requires allocating a
> specified port.
>
> Modify the evtchn_alloc_unbound() to accept the port number as an
> argument and allocate the specified port if available. If the port
> number argument is zero, the next available port will be allocated.
I haven't yet fully reviewed this series. But I would like to point out 
that this opening a security hole (which I thought I had mention before) 
that could be exploited by a guest at runtime.
You would need [1] or similar in order to fix the issue. I am wrote 
"similar" because the patch could potentially be a problem if you allow 
a guest to use FIFO (you may need to allocate a lot of memory to fill 
the hole).
Cheers,

[1] 
https://xenbits.xen.org/gitweb/?p=people/julieng/xen-unstable.git;a=commit;h=2d89486fcf11216331e58a21b367b8a9be1af725
--
Julien Grall