x86, msr: execute on the correct CPU subset

Make rdmsr_on_cpus/wrmsr_on_cpus execute on the current CPU only if it
is in the supplied bitmask.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

arch/x86/lib/msr.c

@@ -89,16 +89,13 @@ void rdmsr_on_cpus(const cpumask_t *mask, u32 msr_no, struct msr *msrs)
 	rv.msrs	  = msrs;
 	rv.msr_no = msr_no;
 
-	preempt_disable();
-	/*
-	 * FIXME: handle the CPU we're executing on separately for now until
-	 * smp_call_function_many has been fixed to not skip it.
-	 */
-	this_cpu = raw_smp_processor_id();
-	smp_call_function_single(this_cpu, __rdmsr_on_cpu, &rv, 1);
+	this_cpu = get_cpu();
+
+	if (cpumask_test_cpu(this_cpu, mask))
+		__rdmsr_on_cpu(&rv);
 
 	smp_call_function_many(mask, __rdmsr_on_cpu, &rv, 1);
-	preempt_enable();
+	put_cpu();
 }
 EXPORT_SYMBOL(rdmsr_on_cpus);
 
@@ -121,16 +118,13 @@ void wrmsr_on_cpus(const cpumask_t *mask, u32 msr_no, struct msr *msrs)
 	rv.msrs   = msrs;
 	rv.msr_no = msr_no;
 
-	preempt_disable();
-	/*
-	 * FIXME: handle the CPU we're executing on separately for now until
-	 * smp_call_function_many has been fixed to not skip it.
-	 */
-	this_cpu = raw_smp_processor_id();
-	smp_call_function_single(this_cpu, __wrmsr_on_cpu, &rv, 1);
+	this_cpu = get_cpu();
+
+	if (cpumask_test_cpu(this_cpu, mask))
+		__wrmsr_on_cpu(&rv);
 
 	smp_call_function_many(mask, __wrmsr_on_cpu, &rv, 1);
-	preempt_enable();
+	put_cpu();
 }
 EXPORT_SYMBOL(wrmsr_on_cpus);