diff options
| author | Ingo Molnar <mingo@elte.hu> | 2008-05-12 21:21:15 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-05-23 18:16:15 +0200 |
| commit | b1979a5fda7869a790f4fd83fb06c78498d26ba1 (patch) | |
| tree | e15546fb2e002fbe1fa0a638c305bd30c8b19df5 | |
| parent | a1289643adb6272c04db9399653ae195072c482a (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>
| -rw-r--r-- | include/asm-x86/tlbflush.h | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/include/asm-x86/tlbflush.h b/include/asm-x86/tlbflush.h index 0c0674d94255..35c76ceb9f40 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) |