Re: [PATCH v10 2/6] x86/sev: Initialize RMPOPT configuration MSRs

[K Prateek Nayak]

Hello Boris,

On 7/23/2026 6:40 AM, Borislav Petkov wrote:
>> +	/*
>> +	 * The RMPOPT_BASE MSR is per-core, so only one thread per core needs
>> +	 * to set up the RMPOPT_BASE MSR.
>> +	 *
>> +	 * Note: only online primary threads are included.  If a core's
>> +	 * primary thread is offline, that core is not covered.  CPU hotplug
> 
> So what happens if not all cores are online?
> 
> This should check that and fail if that is the case instead of blindly
> continuing here.

The offline cores will remain offline since hotplug is disabled. RMPOPT
is simply a performance optimization for RMP checks and leaving the
offline cores (that will never exit idle) unoptimized should be
acceptable.

When hotplug is enabled again, the platform would have already executed
SNP_SHUTDOWN and SnpEn would go back to 0 and RMP checks are disabled
entirely by then.

> 
>> +	 * is not currently supported with SNP enabled.
>> +	 */

-- 
Thanks and Regards,
Prateek