Add a comment how set_mtrr_state() is needing serialization.
Suggested-by: Borislav Petkov <[email protected]>
Signed-off-by: Juergen Gross <[email protected]>
---
V3:
- new patch instead of old patch 1
---
arch/x86/kernel/cpu/mtrr/generic.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c
index 558108296f3c..cd64eab02393 100644
--- a/arch/x86/kernel/cpu/mtrr/generic.c
+++ b/arch/x86/kernel/cpu/mtrr/generic.c
@@ -684,7 +684,10 @@ static u32 deftype_lo, deftype_hi;
/**
* set_mtrr_state - Set the MTRR state for this CPU.
*
- * NOTE: The CPU must already be in a safe state for MTRR changes.
+ * NOTE: The CPU must already be in a safe state for MTRR changes, including
+ * measures that only a single CPU can be active in set_mtrr_state() in
+ * order to not be subject to races for usage of deftype_lo (this is
+ * accomplished by taking set_atomicity_lock).
* RETURNS: 0 if no changes made, else a mask indicating what was changed.
*/
static unsigned long set_mtrr_state(void)
--
2.35.3