The following commit has been merged into the x86/cpu branch of tip: Commit-ID: 01c97c7303580682751b5aaae043b639bdcbacb3 Gitweb: https://git.kernel.org/tip/01c97c7303580682751b5aaae043b639bdcbacb3 Author: Juergen Gross <jgross@xxxxxxxx> AuthorDate: Tue, 04 Oct 2022 10:10:08 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Wed, 19 Oct 2022 20:37:23 +02:00 x86/mtrr: Add comment for set_mtrr_state() serialization Add a comment about set_mtrr_state() needing serialization. [ bp: Touchups. ] Suggested-by: Borislav Petkov <bp@xxxxxxxxx> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lore.kernel.org/r/20220820092533.29420-2-jgross@xxxxxxxx --- 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 5581082..c8f8951 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)
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