Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip:
  x86: Disable large pages on CPUs with Atom erratum AAE44
  x86-64: Clear a 64-bit FS/GS base on fork if selector is nonzero
  x86, mrst: Conditionally register cpu hotplug notifier for apbt

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 7e1cca13af35..1366c7cfd483 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -47,6 +47,27 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
                 (c->x86 == 0x6 && c->x86_model >= 0x0e))
                 set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 
+        /*
+         * Atom erratum AAE44/AAF40/AAG38/AAH41:
+         *
+         * A race condition between speculative fetches and invalidating
+         * a large page.  This is worked around in microcode, but we
+         * need the microcode to have already been loaded... so if it is
+         * not, recommend a BIOS update and disable large pages.
+         */
+        if (c->x86 == 6 && c->x86_model == 0x1c && c->x86_mask <= 2) {
+                u32 ucode, junk;
+
+                wrmsr(MSR_IA32_UCODE_REV, 0, 0);
+                sync_core();
+                rdmsr(MSR_IA32_UCODE_REV, junk, ucode);
+
+                if (ucode < 0x20e) {
+                        printk(KERN_WARNING "Atom PSE erratum detected, BIOS microcode update recommended\n");
+                        clear_cpu_cap(c, X86_FEATURE_PSE);
+                }
+        }
+
 #ifdef CONFIG_X86_64
         set_cpu_cap(c, X86_FEATURE_SYSENTER32);
 #else