+ raid6-simplify-cpu-feature-checks.patch added to mm-nonmm-unstable branch

+ raid6-simplify-cpu-feature-checks.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: raid6: simplify CPU feature checks
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     raid6-simplify-cpu-feature-checks.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/raid6-simplify-cpu-feature-checks.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Eric Biggers <ebiggers@kernel.org>
Subject: raid6: simplify CPU feature checks
Date: Sun, 25 Oct 2026 12:12:07 -0700

Remove unnecessary checks for features that are prerequisites for other
features, such as AVX which is a prerequisite for AVX2.

(Note: in most cases arch/x86/kernel/cpu/cpuid-deps.c warns about
missing prerequisites rather than enforcing them.  This is intentional,
and it does not mean the prerequisites should be checked elsewhere.)

Then, move the raid6_recov_algo_add() lines into the appropriate places
just above so that the same CPU features aren't checked multiple times.

Link: https://lore.kernel.org/20261025191207.86590-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: David Laight <david.laight.linux@gmail.com>
---

 lib/raid/raid6/x86/pq_arch.h |   51 +++++++--------------------------
 1 file changed, 11 insertions(+), 40 deletions(-)

--- a/lib/raid/raid6/x86/pq_arch.h~raid6-simplify-cpu-feature-checks
+++ a/lib/raid/raid6/x86/pq_arch.h
@@ -16,63 +16,34 @@ extern const struct raid6_recov_calls ra
 extern const struct raid6_recov_calls raid6_recov_avx2;
 extern const struct raid6_recov_calls raid6_recov_avx512;
 
-static inline int raid6_has_avx512(void)
-{
-	return boot_cpu_has(X86_FEATURE_AVX2) &&
-		boot_cpu_has(X86_FEATURE_AVX) &&
-		boot_cpu_has(X86_FEATURE_AVX512F) &&
-		boot_cpu_has(X86_FEATURE_AVX512BW) &&
-		boot_cpu_has(X86_FEATURE_AVX512VL) &&
-		boot_cpu_has(X86_FEATURE_AVX512DQ);
-}
-
-static inline bool raid6_has_avx2(void)
-{
-	return boot_cpu_has(X86_FEATURE_AVX2) && boot_cpu_has(X86_FEATURE_AVX);
-}
-
-static inline bool raid6_has_ssse3(void)
-{
-	return boot_cpu_has(X86_FEATURE_XMM) &&
-		boot_cpu_has(X86_FEATURE_XMM2) &&
-		boot_cpu_has(X86_FEATURE_SSSE3);
-}
-
-static inline bool raid6_has_sse2(void)
-{
-	return boot_cpu_has(X86_FEATURE_MMX) &&
-		    boot_cpu_has(X86_FEATURE_FXSR) &&
-		    boot_cpu_has(X86_FEATURE_XMM) &&
-		    boot_cpu_has(X86_FEATURE_XMM2);
-}
-
 static __always_inline void __init arch_raid6_init(void)
 {
-	if (raid6_has_avx2()) {
+	if (boot_cpu_has(X86_FEATURE_AVX2)) {
 		raid6_algo_add(&raid6_avx2x1);
 		raid6_algo_add(&raid6_avx2x2);
 		if (IS_ENABLED(CONFIG_X86_64))
 			raid6_algo_add(&raid6_avx2x4);
-		if (raid6_has_avx512()) {
+		if (boot_cpu_has(X86_FEATURE_AVX512BW) &&
+		    boot_cpu_has(X86_FEATURE_AVX512VL) &&
+		    boot_cpu_has(X86_FEATURE_AVX512DQ)) {
 			raid6_algo_add(&raid6_avx512x1);
 			raid6_algo_add(&raid6_avx512x2);
 			if (IS_ENABLED(CONFIG_X86_64))
 				raid6_algo_add(&raid6_avx512x4);
+			raid6_recov_algo_add(&raid6_recov_avx512);
+		} else {
+			raid6_recov_algo_add(&raid6_recov_avx2);
 		}
-	} else if (IS_ENABLED(CONFIG_X86_64) || raid6_has_sse2()) {
+	} else if (IS_ENABLED(CONFIG_X86_64) ||
+		   boot_cpu_has(X86_FEATURE_XMM2)) {
 		/* x86_64 can assume SSE2 as baseline */
 		raid6_algo_add(&raid6_sse2x1);
 		raid6_algo_add(&raid6_sse2x2);
 		if (IS_ENABLED(CONFIG_X86_64))
 			raid6_algo_add(&raid6_sse2x4);
+		if (boot_cpu_has(X86_FEATURE_SSSE3))
+			raid6_recov_algo_add(&raid6_recov_ssse3);
 	} else {
 		raid6_algo_add_default();
 	}
-
-	if (raid6_has_avx512())
-		raid6_recov_algo_add(&raid6_recov_avx512);
-	else if (raid6_has_avx2())
-		raid6_recov_algo_add(&raid6_recov_avx2);
-	else if (raid6_has_ssse3())
-		raid6_recov_algo_add(&raid6_recov_ssse3);
 }
_

Patches currently in -mm which might be from ebiggers@kernel.org are

xor-remove-obsolete-mmx-optimized-code.patch
raid6-remove-obsolete-mmx-optimized-code.patch
raid6-simplify-cpu-feature-checks.patch