x86/MSR: Chop off lower 32-bit value

sparse complains that the cast truncates the high bits. But here
we really do know what we're doing and we need the lower 32 bits
only as the @low argument. So make that explicit.

Suggested-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1448273546-2567-7-git-send-email-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/include/asm/msr.h

@@ -190,7 +190,7 @@ static inline void wrmsr(unsigned msr, unsigned low, unsigned high)
 
 static inline void wrmsrl(unsigned msr, u64 val)
 {
-	native_write_msr(msr, (u32)val, (u32)(val >> 32));
+	native_write_msr(msr, (u32)(val & 0xffffffffULL), (u32)(val >> 32));
 }
 
 /* wrmsr with exception handling */