Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...

[linux-2.6-block.git] / arch / x86 / kernel / cpu / common.c

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 970ee06dc8aad645dc80d1a8f839aad4f667181e..c7c996a692fd9d6af8d36ac57d6ec70a3e47e620 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -331,6 +331,30 @@ 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.
  */
@@ -896,8 +920,8 @@ static bool __init cpu_vulnerable_to_meltdown(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)
 {
@@ -1188,9 +1212,10 @@ 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.