x86: msr: propagate errors from smp_call_function_single()

Propagate error (-ENXIO) from smp_call_function_single().  These
errors can happen when a CPU is unplugged while the MSR driver is
open.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 10 insertions, 4 deletions

diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c
index e43938086885..9c34a1005dba 100644
--- a/arch/x86/kernel/msr.c
+++ b/arch/x86/kernel/msr.c
@@ -79,8 +79,11 @@ static ssize_t msr_read(struct file *file, char __user *buf,
 
         for (; count; count -= 8) {
                 err = rdmsr_safe_on_cpu(cpu, reg, &data[0], &data[1]);
-                if (err)
-                        return -EIO;
+                if (err) {
+                        if (err == -EFAULT) /* Fix idiotic error code */
+                                err = -EIO;
+                        return err;
+                }
                 if (copy_to_user(tmp, &data, 8))
                         return -EFAULT;
                 tmp += 2;
@@ -105,8 +108,11 @@ static ssize_t msr_write(struct file *file, const char __user *buf,
                 if (copy_from_user(&data, tmp, 8))
                         return -EFAULT;
                 err = wrmsr_safe_on_cpu(cpu, reg, data[0], data[1]);
-                if (err)
-                        return -EIO;
+                if (err) {
+                        if (err == -EFAULT) /* Fix idiotic error code */
+                                err = -EIO;
+                        return err;
+                }
                 tmp += 2;
         }