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

[K Prateek Nayak]

Hello Boris,

On 7/23/2026 10:44 AM, Borislav Petkov wrote:
> On Thu, Jul 23, 2026 at 10:23:56AM +0530, K Prateek Nayak wrote:
>> 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.
> 
> What happens if you boot with a subset of cores, the boot flow enables RMPOPT
> and then you online the rest?

RMPOPT happens at __sev_snp_init_locked() for all online cores. Until
then, SnpEn is still 0 and we don't need RMPOPT because RMP checks
haven't been enabled yet.

> 
> Have we tried that?

That said, Ashish, should snp_rmptable_init() do a
snp_rmpopt_all_physmem() (or something equivalent) when it finds SNP_EN
set in MSR_AMD64_SYSCFG after a kexec?

-- 
Thanks and Regards,
Prateek