ACPI / extlog: Check for RDMSR failure

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: [email protected] References: https://bugs.debian.org/971058 Cc: All applicable <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: Rafael J. Wysocki <[email protected]>
berg · Oct 2, 2020 · 7cecb47 · 7cecb47
1 parent a1b8638
commit 7cecb47
Showing 1 changed file with 3 additions and 3 deletions.
diff --git 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;