Re: [PATCH v2 2/7] x86/sev: add support for enabling RMPOPT

[Kalra, Ashish]

On 3/2/2026 5:00 PM, Dave Hansen wrote:
> On 3/2/26 14:55, Kalra, Ashish wrote:
>>> What's wrong with:
>>>
>>> 	u64 rmpopt_base = pa_start | MSR_AMD64_RMPOPT_ENABLE;
>>> 	...
>>> 	for_each_online_cpu(cpu)
>>> 		wrmsrq_on_cpu(cpu, MSR_AMD64_RMPOPT_BASE, rmpopt_base);
>>>
>>> Then there's at least no ugly casting.
>>>
>> RMOPT_BASE MSRs don't need to be set serially, therefore, by
>> using the cpu_online_mask and on_each_cpu_mask(), we can setup the MSRs
>> concurrently and in parallel. Using for_each_online_cpu() will be slower than
>> doing on_each_cpu_mask() as it doesn't send IPIs in parallel, right.
> 
> If that's the case and you *need* performance, then please go add a
> wrmsrq_on_cpumask() function to do things in parallel.

Sure.

Thanks,
Ashish