Re: [PATCH v36 07/24] x86/cpu/intel: Add nosgx kernel parameter

[Darren Kenny]

On Thursday, 2020-07-16 at 16:52:46 +03, Jarkko Sakkinen wrote:
> Add kernel parameter to disable Intel SGX kernel support.
>
> Tested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Reviewed-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>

Reviewed-by: Darren Kenny <darren.kenny@xxxxxxxxxx>

> ---
>  Documentation/admin-guide/kernel-parameters.txt | 2 ++
>  arch/x86/kernel/cpu/feat_ctl.c                  | 9 +++++++++
>  2 files changed, 11 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index fb95fad81c79..e747bd9ca911 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -3314,6 +3314,8 @@
>  
>  	nosep		[BUGS=X86-32] Disables x86 SYSENTER/SYSEXIT support.
>  
> +	nosgx		[X86-64,SGX] Disables Intel SGX kernel support.
> +
>  	nosmp		[SMP] Tells an SMP kernel to act as a UP kernel,
>  			and disable the IO APIC.  legacy for "maxcpus=0".
>  
> diff --git a/arch/x86/kernel/cpu/feat_ctl.c b/arch/x86/kernel/cpu/feat_ctl.c
> index c3afcd2e4342..1837df39527f 100644
> --- a/arch/x86/kernel/cpu/feat_ctl.c
> +++ b/arch/x86/kernel/cpu/feat_ctl.c
> @@ -101,6 +101,15 @@ static void clear_sgx_caps(void)
>  	setup_clear_cpu_cap(X86_FEATURE_SGX2);
>  }
>  
> +static int __init nosgx(char *str)
> +{
> +	clear_sgx_caps();
> +
> +	return 0;
> +}
> +
> +early_param("nosgx", nosgx);
> +
>  void init_ia32_feat_ctl(struct cpuinfo_x86 *c)
>  {
>  	bool tboot = tboot_enabled();
> -- 
> 2.25.1