1 files changed, 27 insertions, 0 deletions

diff --git a/arch/i386/kernel/verify_cpu.S b/arch/i386/kernel/verify_cpu.S
index b2a9d80b6421..f1d1eacf4ab0 100644
--- a/arch/i386/kernel/verify_cpu.S
+++ b/arch/i386/kernel/verify_cpu.S
@@ -2,6 +2,7 @@
    This runs in 16bit mode so that the caller can still use the BIOS
    to output errors on the screen */
 #include <asm/cpufeature.h>
+#include <asm/msr.h>
 
 verify_cpu:
         pushfl                          # Save caller passed flags
@@ -45,6 +46,32 @@ verify_cpu:
         cmpl    $0x1,%eax
         jb      bad                     # no cpuid 1
 
+#if REQUIRED_MASK1 & NEED_CMPXCHG64
+        /* Some VIA C3s need magic MSRs to enable CX64. Do this here */
+        cmpl    $0x746e6543,%ebx        # Cent
+        jne     1f
+        cmpl    $0x48727561,%edx        # aurH
+        jne     1f
+        cmpl    $0x736c7561,%ecx        # auls
+        jne     1f
+        movl    $1,%eax                 # check model
+        cpuid
+        movl    %eax,%ebx
+        shr     $8,%ebx
+        andl    $0xf,%ebx
+        cmp     $6,%ebx                 # check family == 6
+        jne     1f
+        shr     $4,%eax
+        andl    $0xf,%eax
+        cmpl    $6,%eax                 # check model >= 6
+        jb      1f
+        # assume models >= 6 all support this MSR
+        movl    $MSR_VIA_FCR,%ecx
+        rdmsr
+        orl     $((1<<1)|(1<<7)),%eax   # enable CMPXCHG64 and PGE
+        wrmsr
+1:
+#endif
         movl    $0x1,%eax               # Does the cpu have what it takes
         cpuid