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);