From af2b1c609ff52b6469d8e67696db98c93c348b0e Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 25 Jun 2008 00:18:59 -0400 Subject: [PATCH] x86: add memory barriers to wrmsr wrmsr is a special instruction which can have arbitrary system-wide effects. We don't want the compiler to reorder it with respect to memory operations, so make it a memory barrier. Signed-off-by: Jeremy Fitzhardinge Cc: xen-devel Cc: Stephen Tweedie Cc: Eduardo Habkost Cc: Mark McLoughlin Signed-off-by: Ingo Molnar --- include/asm-x86/msr.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/asm-x86/msr.h b/include/asm-x86/msr.h index 2b5f2c91db25..ca110ee73f07 100644 --- a/include/asm-x86/msr.h +++ b/include/asm-x86/msr.h @@ -66,7 +66,7 @@ static inline unsigned long long native_read_msr_safe(unsigned int msr, static inline void native_write_msr(unsigned int msr, unsigned low, unsigned high) { - asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high)); + asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory"); } static inline int native_write_msr_safe(unsigned int msr, @@ -81,7 +81,8 @@ static inline int native_write_msr_safe(unsigned int msr, _ASM_EXTABLE(2b, 3b) : "=a" (err) : "c" (msr), "0" (low), "d" (high), - "i" (-EFAULT)); + "i" (-EFAULT) + : "memory"); return err; }