[PATCH 6/6] crypto: x86/aes-xts - wire up VAES + AVX10/512 implementation

Eric Biggers
2024-03-26T08:06:04Z

From: Eric Biggers <ebiggers@google.com>

Add an AES-XTS implementation "xts-aes-vaes-avx10_512" for x86_64 CPUs
with the VAES, VPCLMULQDQ, and either AVX10/512 or AVX512BW + AVX512VL
extensions. This implementation uses zmm registers to operate on four
AES blocks at a time. The assembly code is instantiated using a macro
so that most of the source code is shared with other implementations.

To avoid downclocking on older Intel CPU models, an exclusion list is
used to prevent this 512-bit implementation from being used by default
on some CPU models. They will use xts-aes-vaes-avx10_256 instead. For
now, this exclusion list is simply coded into aesni-intel_glue.c. It
may make sense to eventually move it into a more central location.

xts-aes-vaes-avx10_512 is slightly faster than xts-aes-vaes-avx10_256 on
some current CPUs. E.g., on Intel Sapphire Rapids, AES-256-XTS
decryption throughput increases by 5.6% with 4096-byte inputs, or 8.9%
with 512-byte inputs. On AMD Genoa, AES-256-XTS decryption throughput
increases by 15.3% with 4096-byte inputs, or 7.6% with 512-byte inputs.

Future CPUs may provide stronger 512-bit support, in which case a larger
benefit should be seen.

Signed-off-by: Eric Biggers <ebiggers@google.com>
---
arch/x86/crypto/aes-xts-avx-x86_64.S | 9 ++++++++
arch/x86/crypto/aesni-intel_glue.c | 33 +++++++++++++++++++++++++++-
2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/arch/x86/crypto/aes-xts-avx-x86_64.S b/arch/x86/crypto/aes-xts-avx-x86_64.S
index c868b9af443b..024fc12c9a94 100644
--- a/arch/x86/crypto/aes-xts-avx-x86_64.S
+++ b/arch/x86/crypto/aes-xts-avx-x86_64.S
@@ -782,6 +782,15 @@ SYM_TYPED_FUNC_START(aes_xts_encrypt_vaes_avx10_256)
aes_xts_crypt 1
SYM_FUNC_END(aes_xts_encrypt_vaes_avx10_256)
SYM_TYPED_FUNC_START(aes_xts_decrypt_vaes_avx10_256)
aes_xts_crypt 0
SYM_FUNC_END(aes_xts_decrypt_vaes_avx10_256)
+
+.set VL, 64
+.set USE_AVX10, 1
+SYM_TYPED_FUNC_START(aes_xts_encrypt_vaes_avx10_512)
+ aes_xts_crypt 1
+SYM_FUNC_END(aes_xts_encrypt_vaes_avx10_512)
+SYM_TYPED_FUNC_START(aes_xts_decrypt_vaes_avx10_512)
+ aes_xts_crypt 0
+SYM_FUNC_END(aes_xts_decrypt_vaes_avx10_512)
#endif /* CONFIG_AS_VAES && CONFIG_AS_VPCLMULQDQ */
diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index ac45e0b952b7..49b259dff81f 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -1296,12 +1296,32 @@ static struct simd_skcipher_alg *aes_xts_simdalg_##suffix

DEFINE_XTS_ALG(aesni_avx, "xts-aes-aesni-avx", 500);
#if defined(CONFIG_AS_VAES) && defined(CONFIG_AS_VPCLMULQDQ)
DEFINE_XTS_ALG(vaes_avx2, "xts-aes-vaes-avx2", 600);
DEFINE_XTS_ALG(vaes_avx10_256, "xts-aes-vaes-avx10_256", 700);
+DEFINE_XTS_ALG(vaes_avx10_512, "xts-aes-vaes-avx10_512", 800);
#endif

+/*
+ * This is a list of CPU models that are known to suffer from downclocking when
+ * zmm registers (512-bit vectors) are used. On these CPUs, the AES-XTS
+ * implementation with zmm registers won't be used by default. An
+ * implementation with ymm registers (256-bit vectors) will be used instead.
+ */
+static const struct x86_cpu_id zmm_exclusion_list[] = {
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_SKYLAKE_X },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_ICELAKE_X },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_ICELAKE_D },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_ICELAKE },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_ICELAKE_L },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_ICELAKE_NNPI },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_TIGERLAKE_L },
+ { .vendor = X86_VENDOR_INTEL, .family = 6, .model = INTEL_FAM6_TIGERLAKE },
+ /* Allow Rocket Lake and later, and Sapphire Rapids and later. */
+ /* Also allow AMD CPUs (starting with Zen 4, the first with AVX-512). */
+};
+
static int __init register_xts_algs(void)
{
int err;

if (!boot_cpu_has(X86_FEATURE_AVX))
@@ -1331,11 +1351,19 @@ static int __init register_xts_algs(void)

err = simd_register_skciphers_compat(&aes_xts_alg_vaes_avx10_256, 1,
&aes_xts_simdalg_vaes_avx10_256);
if (err)
return err;
-#endif
+
+ if (x86_match_cpu(zmm_exclusion_list))
+ aes_xts_alg_vaes_avx10_512.base.cra_priority = 1;
+
+ err = simd_register_skciphers_compat(&aes_xts_alg_vaes_avx10_512, 1,
+ &aes_xts_simdalg_vaes_avx10_512);
+ if (err)
+ return err;
+#endif /* CONFIG_AS_VAES && CONFIG_AS_VPCLMULQDQ */
return 0;
}

static void unregister_xts_algs(void)
{
@@ -1346,10 +1374,13 @@ static void unregister_xts_algs(void)
simd_unregister_skciphers(&aes_xts_alg_vaes_avx2, 1,
&aes_xts_simdalg_vaes_avx2);
if (aes_xts_simdalg_vaes_avx10_256)
simd_unregister_skciphers(&aes_xts_alg_vaes_avx10_256, 1,
&aes_xts_simdalg_vaes_avx10_256);
+ if (aes_xts_simdalg_vaes_avx10_512)
+ simd_unregister_skciphers(&aes_xts_alg_vaes_avx10_512, 1,
+ &aes_xts_simdalg_vaes_avx10_512);
}
#else
static int __init register_xts_algs(void)
{
return 0;
--
2.44.0