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authorJeremy Fitzhardinge <jeremy@goop.org>2008-06-25 00:18:59 -0400
committerIngo Molnar <mingo@elte.hu>2008-07-08 07:10:24 -0400
commitaf2b1c609ff52b6469d8e67696db98c93c348b0e (patch)
tree794e4ebf8a9ed524cfbd01bc9e7f80fd110d3c2c
parentd338c73c39a6ed0d07fe3bb07c7f12fff0dd237d (diff)
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 <jeremy.fitzhardinge@citrix.com> Cc: xen-devel <xen-devel@lists.xensource.com> Cc: Stephen Tweedie <sct@redhat.com> Cc: Eduardo Habkost <ehabkost@redhat.com> Cc: Mark McLoughlin <markmc@redhat.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--include/asm-x86/msr.h5
1 files 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,
66static inline void native_write_msr(unsigned int msr, 66static inline void native_write_msr(unsigned int msr,
67 unsigned low, unsigned high) 67 unsigned low, unsigned high)
68{ 68{
69 asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high)); 69 asm volatile("wrmsr" : : "c" (msr), "a"(low), "d" (high) : "memory");
70} 70}
71 71
72static inline int native_write_msr_safe(unsigned int msr, 72static inline int native_write_msr_safe(unsigned int msr,
@@ -81,7 +81,8 @@ static inline int native_write_msr_safe(unsigned int msr,
81 _ASM_EXTABLE(2b, 3b) 81 _ASM_EXTABLE(2b, 3b)
82 : "=a" (err) 82 : "=a" (err)
83 : "c" (msr), "0" (low), "d" (high), 83 : "c" (msr), "0" (low), "d" (high),
84 "i" (-EFAULT)); 84 "i" (-EFAULT)
85 : "memory");
85 return err; 86 return err;
86} 87}
87 88