Re: [PATCH v7 2/2] x86 KVM:SVM: Provide "nosnp" boot option for sev kernel command line

[Paluri, PavanKumar]

Hello Boris,

On 10/14/2024 10:40 AM, Borislav Petkov wrote:
> On Mon, Oct 14, 2024 at 08:09:48AM -0500, Pavan Kumar Paluri wrote:
>> @@ -25,6 +26,12 @@ static int __init init_sev_config(char *str)
>>  			continue;
>>  		}
>>  
>> +		if (!strcmp(s, "nosnp")) {
>> +			setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
>> +			cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
>> +			continue;
>> +		}
> 
> Well, if it is a HV-only option, then it better be such:
> 
> @@ -25,6 +26,17 @@ static int __init init_sev_config(char *str)
>  			continue;
>  		}
>  
> +		if (!strcmp(s, "nosnp")) {
> +			if (!cpu_feature_enabled(X86_FEATURE_HYPERVISOR)) {

Sure, it does make sense to add this check since nosnp is only a HV option.

Thanks,
Pavan

> +				setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
> +				cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
> +				continue;
> +			} else {
> +				goto warn;
> +			}
> +		}
> +
> +warn:
>  		pr_info("SEV command-line option '%s' was not recognized\n", s);
>  	}
>  
>