1 files changed, 119 insertions, 0 deletions
diff --git a/arch/x86/lib/msr-on-cpu.c b/arch/x86/lib/msr-on-cpu.c
new file mode 100644
index 000000000000..7767962f25d3
--- /dev/null
+++ b/arch/x86/lib/msr-on-cpu.c
@@ -0,0 +1,119 @@
+#include <linux/module.h>
+#include <linux/preempt.h>
+#include <linux/smp.h>
+#include <asm/msr.h>
+
+struct msr_info {
+	u32 msr_no;
+	u32 l, h;
+	int err;
+};
+
+static void __rdmsr_on_cpu(void *info)
+{
+	struct msr_info *rv = info;
+
+	rdmsr(rv->msr_no, rv->l, rv->h);
+}
+
+static void __rdmsr_safe_on_cpu(void *info)
+{
+	struct msr_info *rv = info;
+
+	rv->err = rdmsr_safe(rv->msr_no, &rv->l, &rv->h);
+}
+
+static int _rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h, int safe)
+{
+	int err = 0;
+	preempt_disable();
+	if (smp_processor_id() == cpu)
+		if (safe)
+			err = rdmsr_safe(msr_no, l, h);
+		else
+			rdmsr(msr_no, *l, *h);
+	else {
+		struct msr_info rv;
+
+		rv.msr_no = msr_no;
+		if (safe) {
+			smp_call_function_single(cpu, __rdmsr_safe_on_cpu,
+						 &rv, 0, 1);
+			err = rv.err;
+		} else {
+			smp_call_function_single(cpu, __rdmsr_on_cpu, &rv, 0, 1);
+		}
+		*l = rv.l;
+		*h = rv.h;
+	}
+	preempt_enable();
+	return err;
+}
+
+static void __wrmsr_on_cpu(void *info)
+{
+	struct msr_info *rv = info;
+
+	wrmsr(rv->msr_no, rv->l, rv->h);
+}
+
+static void __wrmsr_safe_on_cpu(void *info)
+{
+	struct msr_info *rv = info;
+
+	rv->err = wrmsr_safe(rv->msr_no, rv->l, rv->h);
+}
+
+static int _wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h, int safe)
+{
+	int err = 0;
+	preempt_disable();
+	if (smp_processor_id() == cpu)
+		if (safe)
+			err = wrmsr_safe(msr_no, l, h);
+		else
+			wrmsr(msr_no, l, h);
+	else {
+		struct msr_info rv;
+
+		rv.msr_no = msr_no;
+		rv.l = l;
+		rv.h = h;
+		if (safe) {
+			smp_call_function_single(cpu, __wrmsr_safe_on_cpu,
+						 &rv, 0, 1);
+			err = rv.err;
+		} else {
+			smp_call_function_single(cpu, __wrmsr_on_cpu, &rv, 0, 1);
+		}
+	}
+	preempt_enable();
+	return err;
+}
+
+void wrmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
+{
+	_wrmsr_on_cpu(cpu, msr_no, l, h, 0);
+}
+
+void rdmsr_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
+{
+	_rdmsr_on_cpu(cpu, msr_no, l, h, 0);
+}
+
+/* These "safe" variants are slower and should be used when the target MSR
+   may not actually exist. */
+int wrmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 l, u32 h)
+{
+	return _wrmsr_on_cpu(cpu, msr_no, l, h, 1);
+}
+
+int rdmsr_safe_on_cpu(unsigned int cpu, u32 msr_no, u32 *l, u32 *h)
+{
+	return _rdmsr_on_cpu(cpu, msr_no, l, h, 1);
+}
+
+EXPORT_SYMBOL(rdmsr_on_cpu);
+EXPORT_SYMBOL(wrmsr_on_cpu);
+EXPORT_SYMBOL(rdmsr_safe_on_cpu);
+EXPORT_SYMBOL(wrmsr_safe_on_cpu);