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

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Message-ID: <m2wo2brjzi.fsf@oracle.com>
Date:   Thu, 06 Aug 2020 14:18:09 +0100
From:   Darren Kenny <darren.kenny@...cle.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>, x86@...nel.org,
        linux-sgx@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        akpm@...ux-foundation.org, andriy.shevchenko@...ux.intel.com,
        asapek@...gle.com, bp@...en8.de, cedric.xing@...el.com,
        chenalexchen@...gle.com, conradparker@...gle.com,
        cyhanish@...gle.com, dave.hansen@...el.com, haitao.huang@...el.com,
        josh@...htriplett.org, kai.huang@...el.com, kai.svahn@...el.com,
        kmoy@...gle.com, ludloff@...gle.com, luto@...nel.org,
        nhorman@...hat.com, npmccallum@...hat.com, puiterwijk@...hat.com,
        rientjes@...gle.com, tglx@...utronix.de, yaozhangx@...gle.com
Subject: Re: [PATCH v36 07/24] x86/cpu/intel: Add nosgx kernel parameter

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@...el.com>
> Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>

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

> ---
>  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