linux-kernel - Re: [PATCH RESEND v2 1/3] x86/cpu: Create helper to parse clearcpuid param

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Message-ID: <20250217105937.GGZ7MWmb4eTtRaN72e@fat_crate.local>
Date: Mon, 17 Feb 2025 11:59:37 +0100
From: Borislav Petkov <bp@...en8.de>
To: Brendan Jackman <jackmanb@...gle.com>
Cc: Jonathan Corbet <corbet@....net>, Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND v2 1/3] x86/cpu: Create helper to parse clearcpuid
 param

On Wed, Jan 29, 2025 at 03:35:39PM +0000, Brendan Jackman wrote:
> +/*
> + * We parse cpu parameters early because fpu__init_system() is executed

While at it:

s/We parse cpu parameters/Parse CPU parameters/

> + * before parse_early_param().
> + */
> +static void __init cpu_parse_early_param(void)
> +{
> +	char arg[128];
> +	int arglen;
> +
> +#ifdef CONFIG_X86_32
> +	if (cmdline_find_option_bool(boot_command_line, "no387"))
> +#ifdef CONFIG_MATH_EMULATION
> +		setup_clear_cpu_cap(X86_FEATURE_FPU);
> +#else
> +		pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
> +#endif
> +
> +	if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
> +		setup_clear_cpu_cap(X86_FEATURE_FXSR);
> +#endif
> +
> +	if (cmdline_find_option_bool(boot_command_line, "noxsave"))
> +		setup_clear_cpu_cap(X86_FEATURE_XSAVE);
> +
> +	if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
> +		setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
> +
> +	if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
> +		setup_clear_cpu_cap(X86_FEATURE_XSAVES);
> +
> +	if (cmdline_find_option_bool(boot_command_line, "nousershstk"))
> +		setup_clear_cpu_cap(X86_FEATURE_USER_SHSTK);
> +
> +	/* Minimize the gap between FRED is available and available but disabled. */
> +	arglen = cmdline_find_option(boot_command_line, "fred", arg, sizeof(arg));
> +	if (arglen != 2 || strncmp(arg, "on", 2))
> +		setup_clear_cpu_cap(X86_FEATURE_FRED);
> +
> +	arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
> +	if (arglen <= 0)
> +		return;

Newline here.

> +	parse_clearcpuid(arg);
>  }
>  
>  /*
> 
> -- 
> 2.48.1.262.g85cc9f2d1e-goog
> 

-- 
Regards/Gruss,
    Boris.

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