[PATCH 5.9 206/391] ACPI / extlog: Check for RDMSR failure

[Greg Kroah-Hartman]

From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>

commit 7cecb47f55e00282f972a1e0b09136c8cd938221 upstream.

extlog_init() uses rdmsrl() to read an MSR, which on older CPUs
provokes a error message at boot:

    unchecked MSR access error: RDMSR from 0x179 at rIP: 0xcd047307 (native_read_msr+0x7/0x40)

Use rdmsrl_safe() instead, and return -ENODEV if it fails.

Reported-by: jim@xxxxxxxxxxx
Cc: All applicable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/acpi/acpi_extlog.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -222,9 +222,9 @@ static int __init extlog_init(void)
 	u64 cap;
 	int rc;
 
-	rdmsrl(MSR_IA32_MCG_CAP, cap);
-
-	if (!(cap & MCG_ELOG_P) || !extlog_get_l1addr())
+	if (rdmsrl_safe(MSR_IA32_MCG_CAP, &cap) ||
+	    !(cap & MCG_ELOG_P) ||
+	    !extlog_get_l1addr())
 		return -ENODEV;
 
 	rc = -EINVAL;