Re: [PATCH] ioreq_broadcast(): accept partial broadcast success

[Julien Grall <julien@xxxxxxx>]

Hi,

On 25/11/2022 14:15, Per Bilse wrote:
> A change to XAPI varstored causes
For those unfamiliar with XAPI (like me), can you explain what was the 
change made?
> an unnecessary error message
> to be logged in hypervisor.log whenever an RTC timeoffset update
> is broadcast.
>  In extreme cases this could flood the log file.
Which should be ratelimited as this is using guest error loglevel. But I 
think this is irrelevant here. It would be more relevant to explain why 
it is OK to allow a partial broadcast.
> This patch modifies ioreq_broadcast() to allow partial success.
The commit message is quite vague, so it is hard to know what you are 
trying to solve exactly. AFAIU, there are two reasons for 
ioreq_broadcast to fails:
 1) The IOREQ server didn't register the bufioreq
 2) The IOREQ buffer page is full

While I would agree that the error message is not necessary for 1) (the 
IOREQ server doesn't care about the event), I would disagree for 2) 
because it would indicate something went horribly wrong in the IOREQ 
server and there is a chance your domain may misbehave afterwards.
Cheers,

--
Julien Grall