[PATCH] Readd rdmsrl_safe v2

[Andi Kleen <andi@firstfloor.org>]

Readd rdmsrl_safe v2

RDMSR for 64bit values with exception handling.

Makes it easier to deal with 64bit valued MSRs. The old 64bit code
base had that too as checking_rdmsrl(), but it got dropped somehow. 

Needed for followup patch.

v2: switch to inline

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andi Kleen <andi@firstfloor.org>

---
 include/asm-x86/msr.h      |    3 +++
 include/asm-x86/paravirt.h |    4 ++++
 2 files changed, 7 insertions(+)

Index: linux/include/asm-x86/msr.h
===================================================================
--- linux.orig/include/asm-x86/msr.h
+++ linux/include/asm-x86/msr.h
@@ -150,6 +150,13 @@ static inline int wrmsr_safe(unsigned ms
 		__err;							\
 	})
 
+static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
+{
+	int err;
+	*p = native_read_msr_safe(msr, &err);
+	return err;
+}
+
 #define rdtscl(low)						\
 	((low) = (u32)native_read_tsc())
 
Index: linux/include/asm-x86/paravirt.h
===================================================================
--- linux.orig/include/asm-x86/paravirt.h
+++ linux/include/asm-x86/paravirt.h
@@ -687,6 +687,12 @@ static inline int paravirt_write_msr(uns
 	(*b) = _l >> 32;			\
 	_err; })
 
+static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
+{
+	int err;
+	*p = paravirt_read_msr(msr, &err);
+	return err;
+}
 
 static inline u64 paravirt_read_tsc(void)
 {