diff mbox series

[v5,01/16] x86/mtrr: add comment for set_mtrr_state() serialization

Message ID 20221102074713.21493-2-jgross@suse.com
State New
Headers
Series x86: make PAT and MTRR independent from each other |

Commit Message

Juergen Gross Nov. 2, 2022, 7:46 a.m. UTC 
  Add a comment how set_mtrr_state() is needing serialization.

Note that this patch has already been applied to tip.git.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- new patch instead of old patch 1
---
 arch/x86/kernel/cpu/mtrr/generic.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)
diff mbox series

Patch

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)