[PATCH 1/1][Natty] x86, hibernate: Initialize mmu_cr4_features during boot

[Herton Ronaldo Krzesinski]

From: H. Peter Anvin <hpa at linux.intel.com>

Restore the initialization of mmu_cr4_features during boot, which was
removed without comment in checkin e5f15b45ddf3afa2bbbb10c7ea34fb32b6de0a0e

x86: Cleanup highmap after brk is concluded

thereby breaking resume from hibernate.  This restores previous
functionality in approximately the same place, and corrects the
reading of %cr4 on pre-CPUID hardware (%cr4 exists if and only if
CPUID is supported.)

However, part of the problem is that the hibernate suspend/resume
sequence should manage the save/restore of %cr4 explicitly.

Signed-off-by: H. Peter Anvin <hpa at linux.intel.com>
Cc: Rafael J. Wysocki <rjw at sisk.pl>
Cc: Stefano Stabellini <stefano.stabellini at eu.citrix.com>
Cc: Yinghai Lu <yinghai at kernel.org>
LKML-Reference: <201104020154.57136.rjw at sisk.pl>
(cherry picked from commit 4da9484bdece39ab0b098fa711e095e3e9fc8684)
Tested-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
BugLink: http://bugs.launchpad.net/bugs/752870
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 arch/x86/kernel/setup.c |    5 +++++
 1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index e543fe9..4e59873 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1013,6 +1013,11 @@ void __init setup_arch(char **cmdline_p)
 	paging_init();
 	x86_init.paging.pagetable_setup_done(swapper_pg_dir);
 
+	if (boot_cpu_data.cpuid_level >= 0) {
+		/* A CPU has %cr4 if and only if it has CPUID */
+		mmu_cr4_features = read_cr4();
+	}
+
 #ifdef CONFIG_X86_32
 	/* sync back kernel address range */
 	clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,
-- 
1.7.1