diff options
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/traps.c | 26 |
2 files changed, 32 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 31b3a25680d0..d6ea4f42127c 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1539,6 +1539,12 @@ Warning: use of this parameter will taint the kernel and may cause unknown problems. + fred= [X86-64] + Enable/disable Flexible Return and Event Delivery. + Format: { on | off } + on: enable FRED when it's present. + off: disable FRED, the default setting. + ftrace=[tracer] [FTRACE] will set and start the specified tracer as early as possible in order to facilitate early diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c3b2f863acf0..3c3748901825 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -1369,8 +1369,34 @@ DEFINE_IDTENTRY_SW(iret_error) } #endif +/* Do not enable FRED by default yet. */ +static bool enable_fred __ro_after_init = false; + +#ifdef CONFIG_X86_FRED +static int __init fred_setup(char *str) +{ + if (!str) + return -EINVAL; + + if (!cpu_feature_enabled(X86_FEATURE_FRED)) + return 0; + + if (!strcmp(str, "on")) + enable_fred = true; + else if (!strcmp(str, "off")) + enable_fred = false; + else + pr_warn("invalid FRED option: 'fred=%s'\n", str); + return 0; +} +early_param("fred", fred_setup); +#endif + void __init trap_init(void) { + if (cpu_feature_enabled(X86_FEATURE_FRED) && !enable_fred) + setup_clear_cpu_cap(X86_FEATURE_FRED); + /* Init cpu_entry_area before IST entries are set up */ setup_cpu_entry_areas(); |