diff options
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 31 |
1 files changed, 28 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 372ba3fb400f..ef29ad001991 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -329,6 +329,30 @@ static __always_inline void setup_smap(struct cpuinfo_x86 *c) } } +static __always_inline void setup_umip(struct cpuinfo_x86 *c) +{ + /* Check the boot processor, plus build option for UMIP. */ + if (!cpu_feature_enabled(X86_FEATURE_UMIP)) + goto out; + + /* Check the current processor's cpuid bits. */ + if (!cpu_has(c, X86_FEATURE_UMIP)) + goto out; + + cr4_set_bits(X86_CR4_UMIP); + + pr_info("x86/cpu: Activated the Intel User Mode Instruction Prevention (UMIP) CPU feature\n"); + + return; + +out: + /* + * Make sure UMIP is disabled in case it was enabled in a + * previous boot (e.g., via kexec). + */ + cr4_clear_bits(X86_CR4_UMIP); +} + /* * Protection Keys are not available in 32-bit mode. */ @@ -858,8 +882,8 @@ static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c) * cache alignment. * The others are not touched to avoid unwanted side effects. * - * WARNING: this function is only called on the BP. Don't add code here - * that is supposed to run on all CPUs. + * WARNING: this function is only called on the boot CPU. Don't add code + * here that is supposed to run on all CPUs. */ static void __init early_identify_cpu(struct cpuinfo_x86 *c) { @@ -1149,9 +1173,10 @@ static void identify_cpu(struct cpuinfo_x86 *c) /* Disable the PN if appropriate */ squash_the_stupid_serial_number(c); - /* Set up SMEP/SMAP */ + /* Set up SMEP/SMAP/UMIP */ setup_smep(c); setup_smap(c); + setup_umip(c); /* * The vendor-specific functions might have changed features. |