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From:   Robert Elliott <elliott@hpe.com>
To:     tim.c.chen@linux.intel.com, herbert@gondor.apana.org.au,
        davem@davemloft.net, linux-crypto@vger.kernel.org,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        x86@kernel.org, toshi.kani@hpe.com, rwright@hpe.com
Cc:     Robert Elliott <elliott@hpe.com>
Subject: [PATCH] crypto: x86/sha512 - load based on CPU features
Date:   Sat, 13 Aug 2022 18:04:31 -0500
Message-Id: <20220813230431.2666-1-elliott@hpe.com>
MIME-Version: 1.0
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x86 optimized crypto modules built as modules rather than built-in
to the kernel end up as .ko files in the filesystem, e.g., in
/usr/lib/modules. If the filesystem itself is a module, these might
not be available when the crypto API is initialized, resulting in
the generic implementation being used (e.g., sha512_transform rather
than sha512_transform_avx2).

In one test case, CPU utilization in the sha512 function dropped
from 15.34% to 7.18% after forcing loading of the optimized module.

Add module aliases for this x86 optimized crypto module based on CPU
feature bits so udev gets a chance to load them later in the boot
process when the filesystems are all running.

Signed-off-by: Robert Elliott <elliott@hpe.com>
---
 arch/x86/crypto/sha512_ssse3_glue.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/crypto/sha512_ssse3_glue.c b/arch/x86/crypto/sha512_ssse3_glue.c
index 30e70f4fe2f7..6d3b85e53d0e 100644
--- a/arch/x86/crypto/sha512_ssse3_glue.c
+++ b/arch/x86/crypto/sha512_ssse3_glue.c
@@ -36,6 +36,7 @@
 #include <linux/types.h>
 #include <crypto/sha2.h>
 #include <crypto/sha512_base.h>
+#include <asm/cpu_device_id.h>
 #include <asm/simd.h>
 
 asmlinkage void sha512_transform_ssse3(struct sha512_state *state,
@@ -284,6 +285,13 @@ static int register_sha512_avx2(void)
 			ARRAY_SIZE(sha512_avx2_algs));
 	return 0;
 }
+static const struct x86_cpu_id module_cpu_ids[] = {
+	X86_MATCH_FEATURE(X86_FEATURE_AVX2, NULL),
+	X86_MATCH_FEATURE(X86_FEATURE_AVX, NULL),
+	X86_MATCH_FEATURE(X86_FEATURE_SSSE3, NULL),
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, module_cpu_ids);
 
 static void unregister_sha512_avx2(void)
 {
@@ -294,6 +302,8 @@ static void unregister_sha512_avx2(void)
 
 static int __init sha512_ssse3_mod_init(void)
 {
+	if (!x86_match_cpu(module_cpu_ids))
+		return -ENODEV;
 
 	if (register_sha512_ssse3())
 		goto fail;
-- 
2.37.1