Re: [PATCH 3/4] crypto/ccp: support setting RAPL_DIS in SNP_INIT_EX

[Sean Christopherson <seanjc@google.com>]

On Mon, Feb 23, 2026, Tycho Andersen wrote:
> From: "Tycho Andersen (AMD)" <tycho@kernel.org>
> 
> The kernel allows setting the RAPL_DIS policy bit, but had no way to set

Please actually say what RAPL_DIS is and does, and explain why this is the
correct approach.  I genuinely have no idea what the impact of this patch is,
(beyond disabling something, obviously).

> the RAPL_DIS bit during SNP_INIT_EX. Setting the policy bit would always
> result in:
> 
>     [  898.840286] ccp 0000:a9:00.5: sev command 0xa0 failed (0x00000007)
> 
> Allow setting the RAPL_DIS bit during SNP_INIT_EX via a module parameter.
> If the hardware does not support RAPL_DIS, log and disable the module
> parameter.
> 
> Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
> ---
>  drivers/crypto/ccp/sev-dev.c | 14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 096f993974d1..362126453ef0 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -75,6 +75,10 @@ static bool psp_init_on_probe = true;
>  module_param(psp_init_on_probe, bool, 0444);
>  MODULE_PARM_DESC(psp_init_on_probe, "  if true, the PSP will be initialized on module init. Else the PSP will be initialized on the first command requiring it");
>  
> +static bool rapl_disable;
> +module_param(rapl_disable, bool, 0444);
> +MODULE_PARM_DESC(rapl_disable, "  if true, the RAPL_DIS bit will be set during INIT_EX if supported");
> +
>  #if IS_ENABLED(CONFIG_PCI_TSM)
>  static bool sev_tio_enabled = true;
>  module_param_named(tio, sev_tio_enabled, bool, 0444);
> @@ -1428,6 +1432,16 @@ static int __sev_snp_init_locked(int *error, unsigned int max_snp_asid)
>  			data.max_snp_asid = max_snp_asid;
>  		}
>  
> +		if (rapl_disable) {
> +			if (sev->snp_feat_info_0.ecx & SNP_RAPL_DISABLE_SUPPORTED) {
> +				data.rapl_dis = 1;
> +			} else {
> +				dev_info(sev->dev,
> +					"SEV: RAPL_DIS requested, but not supported");
> +				rapl_disable = false;
> +			}
> +		}
> +
>  		data.init_rmp = 1;
>  		data.list_paddr_en = 1;
>  		data.list_paddr = __psp_pa(snp_range_list);
> -- 
> 2.53.0
>