x86: re-add rdmsrl_safe

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.

Signed-off-by: Andi Kleen <andi@firstfloor.org>
Cc: andreas.herrmann3@amd.com
Cc: mingo@elte.hu
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/asm-x86/msr.h b/include/asm-x86/msr.h
index 2c698a2e81f9..3707650a169b 100644
--- a/include/asm-x86/msr.h
+++ b/include/asm-x86/msr.h
@@ -150,6 +150,14 @@ static inline int wrmsr_safe(unsigned msr, unsigned low, unsigned high)
         __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())