The following commit has been merged into the x86/core branch of tip:
Commit-ID: 7e67f3617228318da655dc87bc705f9c5f7bb101
Gitweb: https://git.kernel.org/tip/7e67f3617228318da655dc87bc705f9c5f7bb101
Author: Sohil Mehta <sohil.mehta@intel.com>
AuthorDate: Wed, 19 Feb 2025 18:41:20
Committer: Ingo Molnar <mingo@kernel.org>
CommitterDate: Wed, 19 Mar 2025 11:19:31 +01:00
x86/cpu/intel: Fix the MOVSL alignment preference for extended Families
The alignment preference for 32-bit MOVSL based bulk memory move has
been 8-byte for a long time. However this preference is only set for
Family 6 and 15 processors.
Use the same preference for upcoming Family numbers 18 and 19. Also, use
a simpler VFM based check instead of switching based on Family numbers.
Refresh the comment to reflect the new check.
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250219184133.816753-3-sohil.mehta@intel.com
---
arch/x86/kernel/cpu/intel.c | 19 ++++++-------------
1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 291c828..99b4c40 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -440,23 +440,16 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
(c->x86_stepping < 0x6 || c->x86_stepping == 0xb))
set_cpu_bug(c, X86_BUG_11AP);
-
#ifdef CONFIG_X86_INTEL_USERCOPY
/*
- * Set up the preferred alignment for movsl bulk memory moves
+ * MOVSL bulk memory moves can be slow when source and dest are not
+ * both 8-byte aligned. PII/PIII only like MOVSL with 8-byte alignment.
+ *
+ * Set the preferred alignment for Pentium Pro and newer processors, as
+ * it has only been tested on these.
*/
- switch (c->x86) {
- case 4: /* 486: untested */
- break;
- case 5: /* Old Pentia: untested */
- break;
- case 6: /* PII/PIII only like movsl with 8-byte alignment */
+ if (c->x86_vfm >= INTEL_PENTIUM_PRO)
movsl_mask.mask = 7;
- break;
- case 15: /* P4 is OK down to 8-byte alignment */
- movsl_mask.mask = 7;
- break;
- }
#endif
intel_smp_check(c);