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x86/cpu: Create helper function to parse the 'clearcpuid=' boot parameter

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This is in preparation for a later commit that will reuse this code, to
make review convenient.

Factor out a helper function which does the full handling for this arg
including printing info to the console.

No functional change intended.

Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20241220-force-cpu-bug-v2-1-7dc71bce742a@google.com
This commit is contained in:
Brendan Jackman 2024-12-20 15:18:31 +00:00 committed by Ingo Molnar
parent a4248ee16f
commit f034937f5a
1 changed files with 52 additions and 44 deletions
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96
arch/x86/kernel/cpu/common.c
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@ -1479,56 +1479,18 @@ static void detect_nopl(void)
#endif
}
/*
* We parse cpu parameters early because fpu__init_system() is executed
* before parse_early_param().
*/
static void __init cpu_parse_early_param(void)
static inline void parse_clearcpuid(char *arg)
{
char arg[128];
char *argptr = arg, *opt;
int arglen, taint = 0;
#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;
char *opt;
int taint = 0;
pr_info("Clearing CPUID bits:");
while (argptr) {
while (arg) {
bool found __maybe_unused = false;
unsigned int bit;
opt = strsep(&argptr, ",");
opt = strsep(&arg, ",");
/*
* Handle naked numbers first for feature flags which don't
@ -1570,10 +1532,56 @@ static void __init cpu_parse_early_param(void)
if (!found)
pr_cont(" (unknown: %s)", opt);
}
pr_cont("\n");
if (taint)
add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
pr_cont("\n");
}
/*
* We parse cpu parameters early because fpu__init_system() is executed
* 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;
parse_clearcpuid(arg);
}
/*