Re: [PATCH v5 4/7] x86/sev: Add support to perform RMP optimizations asynchronously

[Kalra, Ashish]

On 5/28/2026 6:52 PM, Kalra, Ashish wrote:
> Hello Ackerley,

>>> +	/*
>>> +	 * RMPOPT scans the RMP table, stores the result of the scan in the
>>> +	 * reserved processor memory. The RMP scan is the most expensive
>>> +	 * part. If a second RMPOPT occurs, it can skip the expensive scan
>>> +	 * if they can see a cached result in the reserved processor memory.
>>> +	 *
>>> +	 * Do RMPOPT on one CPU alone. Then, follow that up with RMPOPT
>>> +	 * on every other primary thread. This potentially allows the
>>
>> I like the leader and follower comments below, thanks! With this
>> leader/follower setup, will the followers definitely see the cached scan
>> results, or might the followers still potentially not benefit from the
>> caching? If it's still only "potentially", why?
> 
> I am verifying with the H/W architects if this is always going to be true or not,
> will the followers always benefit from the scan results cached by the leader (first CPU)
> or there is a possibility that the followers cannot see/access/get the cached results
> and instead do full RMP scanning ?
> 

Following up on this, i have checked with the H/W architects, and the feedback is that
the: followers are "designed to" skip the scan if they see a cached result.

Thanks,
Ashish