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authorIngo Molnar <mingo@elte.hu>2008-05-12 21:21:15 +0200
committerThomas Gleixner <tglx@linutronix.de>2008-05-23 18:16:15 +0200
commitb1979a5fda7869a790f4fd83fb06c78498d26ba1 (patch)
treee15546fb2e002fbe1fa0a638c305bd30c8b19df5 /include/asm-x86
parenta1289643adb6272c04db9399653ae195072c482a (diff)
x86: prevent PGE flush from interruption/preemption
CR4 manipulation is not protected against interrupts and preemption, but KVM uses smp_function_call to manipulate the X86_CR4_VMXE bit either from the CPU hotplug code or from the kvm_init call. We need to protect the CR4 manipulation from both interrupts and preemption. Original bug report: http://lkml.org/lkml/2008/5/7/48 Bugzilla entry: http://bugzilla.kernel.org/show_bug.cgi?id=10642 This is not a regression from 2.6.25, it's a long standing and hard to trigger bug. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'include/asm-x86')
-rw-r--r--include/asm-x86/tlbflush.h13
1 files changed, 12 insertions, 1 deletions
diff --git a/include/asm-x86/tlbflush.h b/include/asm-x86/tlbflush.h
index 0c0674d9425..35c76ceb9f4 100644
--- a/include/asm-x86/tlbflush.h
+++ b/include/asm-x86/tlbflush.h
@@ -22,12 +22,23 @@ static inline void __native_flush_tlb(void)
static inline void __native_flush_tlb_global(void)
{
- unsigned long cr4 = read_cr4();
+ unsigned long flags;
+ unsigned long cr4;
+ /*
+ * Read-modify-write to CR4 - protect it from preemption and
+ * from interrupts. (Use the raw variant because this code can
+ * be called from deep inside debugging code.)
+ */
+ raw_local_irq_save(flags);
+
+ cr4 = read_cr4();
/* clear PGE */
write_cr4(cr4 & ~X86_CR4_PGE);
/* write old PGE again and flush TLBs */
write_cr4(cr4);
+
+ raw_local_irq_restore(flags);
}
static inline void __native_flush_tlb_single(unsigned long addr)