linux-kernel - [tip:x86/urgent] x86, hibernate: Initialize mmu_cr4

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Date:	Wed, 6 Apr 2011 20:28:00 GMT
From:	"tip-bot for H. Peter Anvin" <hpa@...ux.intel.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...hat.com,
	yinghai@...nel.org, stefano.stabellini@...citrix.com,
	tglx@...utronix.de, hpa@...ux.intel.com, rjw@...k.pl
Subject: [tip:x86/urgent] x86, hibernate: Initialize mmu_cr4_features during boot

Commit-ID:  4da9484bdece39ab0b098fa711e095e3e9fc8684
Gitweb:     http://git.kernel.org/tip/4da9484bdece39ab0b098fa711e095e3e9fc8684
Author:     H. Peter Anvin <hpa@...ux.intel.com>
AuthorDate: Wed, 6 Apr 2011 13:10:02 -0700
Committer:  H. Peter Anvin <hpa@...ux.intel.com>
CommitDate: Wed, 6 Apr 2011 13:10:02 -0700

x86, hibernate: Initialize mmu_cr4_features during boot

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@...ux.intel.com>
Cc: Rafael J. Wysocki <rjw@...k.pl>
Cc: Stefano Stabellini <stefano.stabellini@...citrix.com>
Cc: Yinghai Lu <yinghai@...nel.org>
LKML-Reference: <201104020154.57136.rjw@...k.pl>
---
 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 5a0484a..4be9b39 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -976,6 +976,11 @@ 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,
--
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