Messages in this thread Patch in this message | | | From | Juergen Gross <> | Subject | [PATCH v4 01/16] x86/mtrr: add comment for set_mtrr_state() serialization | Date | Tue, 4 Oct 2022 10:10:08 +0200 |
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Add a comment how set_mtrr_state() is needing serialization.
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 --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
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