Re: [PATCH v11 3/6] x86/sev: Initialize RMPOPT configuration MSRs

[Borislav Petkov]

On Mon, Jul 27, 2026 at 07:04:57PM +0000, Ashish Kalra wrote:
> @@ -705,10 +760,12 @@ bool snp_probe_rmptable_info(void)
>  	if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP))
>  		rdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg);
>  
> -	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED)
> +	if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED) {
>  		return probe_segmented_rmptable_info();
> -	else
> +	} else {
> +		setup_clear_cpu_cap(X86_FEATURE_RMPOPT);

That looks a bit squirreled away in a probing function. Let's make that a bit
more obvious:

bool snp_probe_rmptable_info(void)
{
        if (cpu_feature_enabled(X86_FEATURE_SEGMENTED_RMP)) {
                rdmsrq(MSR_AMD64_RMP_CFG, rmp_cfg);

                if (rmp_cfg & MSR_AMD64_SEG_RMP_ENABLED)
                        return probe_segmented_rmptable_info();
        } else {
                /* RMPOPT is supported only with a segmented RMP table. */
                setup_clear_cpu_cap(X86_FEATURE_RMPOPT);

                return probe_contiguous_rmptable_info();
        }       
}

> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index ca473ca198b8..c002a7ca26a8 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -1477,6 +1477,9 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
>  	}
>  
>  	snp_hv_fixed_pages_state_update(sev, HV_FIXED);
> +
> +	snp_setup_rmpopt();

Why is this thing here and not at the end?

SEV-TIO is supposed to always run last or it doesn't matter?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette