The following commit has been merged into the x86/cpu branch of tip: Commit-ID: f034937f5af32188cd1c07865c885b2f171e17bf Gitweb: https://git.kernel.org/tip/f034937f5af32188cd1c07865c885b2f171e17bf Author: Brendan Jackman <jackmanb@xxxxxxxxxx> AuthorDate: Fri, 20 Dec 2024 15:18:31 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Fri, 28 Feb 2025 10:57:49 +01:00 x86/cpu: Create helper function to parse the 'clearcpuid=' boot parameter 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@xxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20241220-force-cpu-bug-v2-1-7dc71bce742a@xxxxxxxxxx --- arch/x86/kernel/cpu/common.c | 96 ++++++++++++++++++----------------- 1 file changed, 52 insertions(+), 44 deletions(-) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 76598a9..137d3e0 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -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); } /*
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