x86, realmode: read cr4 and EFER from kernel for 64-bit trampoline

This patch changes 64-bit trampoline so that CR4 and
EFER are provided by the kernel instead of using fixed
values.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@intel.com>
Link: http://lkml.kernel.org/r/1336501366-28617-24-git-send-email-jarkko.sakkinen@intel.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 4fa7dcceb6c0..404583ccf0cf 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -544,13 +544,16 @@ static inline void load_sp0(struct tss_struct *tss,
  * enable), so that any CPU's that boot up
  * after us can get the correct flags.
  */
-extern unsigned long            mmu_cr4_features;
+extern unsigned long mmu_cr4_features;
+extern u32 *trampoline_cr4_features;
 
 static inline void set_in_cr4(unsigned long mask)
 {
         unsigned long cr4;
 
         mmu_cr4_features |= mask;
+        if (trampoline_cr4_features)
+                *trampoline_cr4_features = mmu_cr4_features;
         cr4 = read_cr4();
         cr4 |= mask;
         write_cr4(cr4);
@@ -561,6 +564,8 @@ static inline void clear_in_cr4(unsigned long mask)
         unsigned long cr4;
 
         mmu_cr4_features &= ~mask;
+        if (trampoline_cr4_features)
+                *trampoline_cr4_features = mmu_cr4_features;
         cr4 = read_cr4();
         cr4 &= ~mask;
         write_cr4(cr4);