Commit af2b1c60 authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Ingo Molnar
Browse files

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: default avatarJeremy 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: default avatarIngo Molnar <mingo@elte.hu>
parent d338c73c

include/asm-x86/msr.h

+3 −2
Original line number Diff line number Diff line
@@ -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;

}

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