crypto: x86/aes-gcm - add VAES and AVX512 / AVX10 optimized AES-GCM

Add implementations of AES-GCM for x86_64 CPUs that support VAES (vector
AES), VPCLMULQDQ (vector carryless multiplication), and either AVX512 or
AVX10.  There are two implementations, sharing most source code: one
using 256-bit vectors and one using 512-bit vectors.  This patch
improves AES-GCM performance by up to 162%; see Tables 1 and 2 below.

I wrote the new AES-GCM assembly code from scratch, focusing on
correctness, performance, code size (both source and binary), and
documenting the source.  The new assembly file aes-gcm-avx10-x86_64.S is
about 1200 lines including extensive comments, and it generates less
than 8 KB of binary code.  The main loop does 4 vectors at a time, with
the AES and GHASH instructions interleaved.  Any remainder is handled
using a simple 1 vector at a time loop, with masking.

Several VAES + AVX512 implementations of AES-GCM exist from Intel,
including one in OpenSSL and one proposed for inclusion in Linux in 2021
(https://lore.kernel.org/linux-crypto/1611386920-28579-6-git-send-email-megha.dey@intel.com/).
These aren't really suitable to be used, though, due to the massive
amount of binary code generated (696 KB for OpenSSL, 200 KB for Linux)
and well as the significantly larger amount of assembly source (4978
lines for OpenSSL, 1788 lines for Linux).  Also, Intel's code does not
support 256-bit vectors, which makes it not usable on future
AVX10/256-only CPUs, and also not ideal for certain Intel CPUs that have
downclocking issues.  So I ended up starting from scratch.  Usually my
much shorter code is actually slightly faster than Intel's AVX512 code,
though it depends on message length and on which of Intel's
implementations is used; for details, see Tables 3 and 4 below.

To facilitate potential integration into other projects, I've
dual-licensed aes-gcm-avx10-x86_64.S under Apache-2.0 OR BSD-2-Clause,
the same as the recently added RISC-V crypto code.

The following two tables summarize the performance improvement over the
existing AES-GCM code in Linux that uses AES-NI and AVX2:

Table 1: AES-256-GCM encryption throughput improvement,
         CPU microarchitecture vs. message length in bytes:

                      | 16384 |  4096 |  4095 |  1420 |   512 |   500 |
----------------------+-------+-------+-------+-------+-------+-------+
Intel Ice Lake        |   42% |   48% |   60% |   62% |   70% |   69% |
Intel Sapphire Rapids |  157% |  145% |  162% |  119% |   96% |   96% |
Intel Emerald Rapids  |  156% |  144% |  161% |  115% |   95% |  100% |
AMD Zen 4             |  103% |   89% |   78% |   56% |   54% |   54% |

                      |   300 |   200 |    64 |    63 |    16 |
----------------------+-------+-------+-------+-------+-------+
Intel Ice Lake        |   66% |   48% |   49% |   70% |   53% |
Intel Sapphire Rapids |   80% |   60% |   41% |   62% |   38% |
Intel Emerald Rapids  |   79% |   60% |   41% |   62% |   38% |
AMD Zen 4             |   51% |   35% |   27% |   32% |   25% |

Table 2: AES-256-GCM decryption throughput improvement,
         CPU microarchitecture vs. message length in bytes:

                      | 16384 |  4096 |  4095 |  1420 |   512 |   500 |
----------------------+-------+-------+-------+-------+-------+-------+
Intel Ice Lake        |   42% |   48% |   59% |   63% |   67% |   71% |
Intel Sapphire Rapids |  159% |  145% |  161% |  125% |  102% |  100% |
Intel Emerald Rapids  |  158% |  144% |  161% |  124% |  100% |  103% |
AMD Zen 4             |  110% |   95% |   80% |   59% |   56% |   54% |

                      |   300 |   200 |    64 |    63 |    16 |
----------------------+-------+-------+-------+-------+-------+
Intel Ice Lake        |   67% |   56% |   46% |   70% |   56% |
Intel Sapphire Rapids |   79% |   62% |   39% |   61% |   39% |
Intel Emerald Rapids  |   80% |   62% |   40% |   58% |   40% |
AMD Zen 4             |   49% |   36% |   30% |   35% |   28% |

The above numbers are percentage improvements in single-thread
throughput, so e.g. an increase from 4000 MB/s to 6000 MB/s would be
listed as 50%.  They were collected by directly measuring the Linux
crypto API performance using a custom kernel module.  Note that indirect
benchmarks (e.g. 'cryptsetup benchmark' or benchmarking dm-crypt I/O)
include more overhead and won't see quite as much of a difference.  All
these benchmarks used an associated data length of 16 bytes.  Note that
AES-GCM is almost always used with short associated data lengths.

The following two tables summarize how the performance of my code
compares with Intel's AVX512 AES-GCM code, both the version that is in
OpenSSL and the version that was proposed for inclusion in Linux.
Neither version exists in Linux currently, but these are alternative
AES-GCM implementations that could be chosen instead of mine.  I
collected the following numbers on Emerald Rapids using a userspace
benchmark program that calls the assembly functions directly.

I've also included a comparison with Cloudflare's AES-GCM implementation
from https://boringssl-review.googlesource.com/c/boringssl/+/65987/3.

Table 3: VAES-based AES-256-GCM encryption throughput in MB/s,
         implementation name vs. message length in bytes:

                     | 16384 |  4096 |  4095 |  1420 |   512 |   500 |
---------------------+-------+-------+-------+-------+-------+-------+
This implementation  | 14171 | 12956 | 12318 |  9588 |  7293 |  6449 |
AVX512_Intel_OpenSSL | 14022 | 12467 | 11863 |  9107 |  5891 |  6472 |
AVX512_Intel_Linux   | 13954 | 12277 | 11530 |  8712 |  6627 |  5898 |
AVX512_Cloudflare    | 12564 | 11050 | 10905 |  8152 |  5345 |  5202 |

                     |   300 |   200 |    64 |    63 |    16 |
---------------------+-------+-------+-------+-------+-------+
This implementation  |  4939 |  3688 |  1846 |  1821 |   738 |
AVX512_Intel_OpenSSL |  4629 |  4532 |  2734 |  2332 |  1131 |
AVX512_Intel_Linux   |  4035 |  2966 |  1567 |  1330 |   639 |
AVX512_Cloudflare    |  3344 |  2485 |  1141 |  1127 |   456 |

Table 4: VAES-based AES-256-GCM decryption throughput in MB/s,
         implementation name vs. message length in bytes:

                     | 16384 |  4096 |  4095 |  1420 |   512 |   500 |
---------------------+-------+-------+-------+-------+-------+-------+
This implementation  | 14276 | 13311 | 13007 | 11086 |  8268 |  8086 |
AVX512_Intel_OpenSSL | 14067 | 12620 | 12421 |  9587 |  5954 |  7060 |
AVX512_Intel_Linux   | 14116 | 12795 | 11778 |  9269 |  7735 |  6455 |
AVX512_Cloudflare    | 13301 | 12018 | 11919 |  9182 |  7189 |  6726 |

                     |   300 |   200 |    64 |    63 |    16 |
---------------------+-------+-------+-------+-------+-------+
This implementation  |  6454 |  5020 |  2635 |  2602 |  1079 |
AVX512_Intel_OpenSSL |  5184 |  5799 |  2957 |  2545 |  1228 |
AVX512_Intel_Linux   |  4394 |  4247 |  2235 |  1635 |   922 |
AVX512_Cloudflare    |  4289 |  3851 |  1435 |  1417 |   574 |

So, usually my code is actually slightly faster than Intel's code,
though the OpenSSL implementation has a slight edge on messages shorter
than 256 bytes in this microbenchmark.  (This also holds true when doing
the same tests on AMD Zen 4.)  It can be seen that the large code size
(up to 94x larger!) of the Intel implementations doesn't seem to bring
much benefit, so starting from scratch with much smaller code, as I've
done, seems appropriate.  The performance of my code on messages shorter
than 256 bytes could be improved through a limited amount of unrolling,
but it's unclear it would be worth it, given code size considerations
(e.g. caches) that don't get measured in microbenchmarks.

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 533 insertions, 16 deletions

diff --git a/arch/x86/crypto/aesni-intel_glue.c b/arch/x86/crypto/aesni-intel_glue.c
index ef031655b2d3..c1cc01583103 100644
--- a/arch/x86/crypto/aesni-intel_glue.c
+++ b/arch/x86/crypto/aesni-intel_glue.c
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * Support for Intel AES-NI instructions. This file contains glue
- * code, the real AES implementation is in intel-aes_asm.S.
+ * Support for AES-NI and VAES instructions.  This file contains glue code.
+ * The real AES implementations are in aesni-intel_asm.S and other .S files.
  *
  * Copyright (C) 2008, Intel Corp.
  *    Author: Huang Ying <ying.huang@intel.com>
@@ -13,6 +13,8 @@
  *             Tadeusz Struk (tadeusz.struk@intel.com)
  *             Aidan O'Mahony (aidan.o.mahony@intel.com)
  *    Copyright (c) 2010, Intel Corporation.
+ *
+ * Copyright 2024 Google LLC
  */
 
 #include <linux/hardirq.h>
@@ -1214,13 +1216,505 @@ DEFINE_XTS_ALG(aesni_avx, "xts-aes-aesni-avx", 500);
 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
+
+/* The common part of the x86_64 AES-GCM key struct */
+struct aes_gcm_key {
+	/* Expanded AES key and the AES key length in bytes */
+	struct crypto_aes_ctx aes_key;
+
+	/* RFC4106 nonce (used only by the rfc4106 algorithms) */
+	u32 rfc4106_nonce;
+};
+
+/* Key struct used by the VAES + AVX10 implementations of AES-GCM */
+struct aes_gcm_key_avx10 {
+	/*
+	 * Common part of the key.  The assembly code prefers 16-byte alignment
+	 * for the round keys; we get this by them being located at the start of
+	 * the struct and the whole struct being 64-byte aligned.
+	 */
+	struct aes_gcm_key base;
+
+	/*
+	 * Powers of the hash key H^16 through H^1.  These are 128-bit values.
+	 * They all have an extra factor of x^-1 and are byte-reversed.  This
+	 * array is aligned to a 64-byte boundary to make it naturally aligned
+	 * for 512-bit loads, which can improve performance.  (The assembly code
+	 * doesn't *need* the alignment; this is just an optimization.)
+	 */
+	u64 h_powers[16][2] __aligned(64);
+
+	/* Three padding blocks required by the assembly code */
+	u64 padding[3][2];
+};
+#define AES_GCM_KEY_AVX10(key)	\
+	container_of((key), struct aes_gcm_key_avx10, base)
+#define AES_GCM_KEY_AVX10_SIZE	\
+	(sizeof(struct aes_gcm_key_avx10) + (63 & ~(CRYPTO_MINALIGN - 1)))
+
+/*
+ * These flags are passed to the AES-GCM helper functions to specify the
+ * specific version of AES-GCM (RFC4106 or not), whether it's encryption or
+ * decryption, and which assembly functions should be called.  Assembly
+ * functions are selected using flags instead of function pointers to avoid
+ * indirect calls (which are very expensive on x86) regardless of inlining.
+ */
+#define FLAG_RFC4106	BIT(0)
+#define FLAG_ENC	BIT(1)
+#define FLAG_AVX10_512	BIT(2)
+
+static inline struct aes_gcm_key *
+aes_gcm_key_get(struct crypto_aead *tfm, int flags)
+{
+	return PTR_ALIGN(crypto_aead_ctx(tfm), 64);
+}
+
+asmlinkage void
+aes_gcm_precompute_vaes_avx10_256(struct aes_gcm_key_avx10 *key);
+asmlinkage void
+aes_gcm_precompute_vaes_avx10_512(struct aes_gcm_key_avx10 *key);
+
+static void aes_gcm_precompute(struct aes_gcm_key *key, int flags)
+{
+	/*
+	 * To make things a bit easier on the assembly side, the AVX10
+	 * implementations use the same key format.  Therefore, a single
+	 * function using 256-bit vectors would suffice here.  However, it's
+	 * straightforward to provide a 512-bit one because of how the assembly
+	 * code is structured, and it works nicely because the total size of the
+	 * key powers is a multiple of 512 bits.  So we take advantage of that.
+	 */
+	if (flags & FLAG_AVX10_512)
+		aes_gcm_precompute_vaes_avx10_512(AES_GCM_KEY_AVX10(key));
+	else
+		aes_gcm_precompute_vaes_avx10_256(AES_GCM_KEY_AVX10(key));
+}
+
+asmlinkage void
+aes_gcm_aad_update_vaes_avx10(const struct aes_gcm_key_avx10 *key,
+			      u8 ghash_acc[16], const u8 *aad, int aadlen);
+
+static void aes_gcm_aad_update(const struct aes_gcm_key *key, u8 ghash_acc[16],
+			       const u8 *aad, int aadlen, int flags)
+{
+	aes_gcm_aad_update_vaes_avx10(AES_GCM_KEY_AVX10(key), ghash_acc,
+				      aad, aadlen);
+}
+
+asmlinkage void
+aes_gcm_enc_update_vaes_avx10_256(const struct aes_gcm_key_avx10 *key,
+				  const u32 le_ctr[4], u8 ghash_acc[16],
+				  const u8 *src, u8 *dst, int datalen);
+asmlinkage void
+aes_gcm_enc_update_vaes_avx10_512(const struct aes_gcm_key_avx10 *key,
+				  const u32 le_ctr[4], u8 ghash_acc[16],
+				  const u8 *src, u8 *dst, int datalen);
+
+asmlinkage void
+aes_gcm_dec_update_vaes_avx10_256(const struct aes_gcm_key_avx10 *key,
+				  const u32 le_ctr[4], u8 ghash_acc[16],
+				  const u8 *src, u8 *dst, int datalen);
+asmlinkage void
+aes_gcm_dec_update_vaes_avx10_512(const struct aes_gcm_key_avx10 *key,
+				  const u32 le_ctr[4], u8 ghash_acc[16],
+				  const u8 *src, u8 *dst, int datalen);
+
+/* __always_inline to optimize out the branches based on @flags */
+static __always_inline void
+aes_gcm_update(const struct aes_gcm_key *key,
+	       const u32 le_ctr[4], u8 ghash_acc[16],
+	       const u8 *src, u8 *dst, int datalen, int flags)
+{
+	if (flags & FLAG_ENC) {
+		if (flags & FLAG_AVX10_512)
+			aes_gcm_enc_update_vaes_avx10_512(AES_GCM_KEY_AVX10(key),
+							  le_ctr, ghash_acc,
+							  src, dst, datalen);
+		else
+			aes_gcm_enc_update_vaes_avx10_256(AES_GCM_KEY_AVX10(key),
+							  le_ctr, ghash_acc,
+							  src, dst, datalen);
+	} else {
+		if (flags & FLAG_AVX10_512)
+			aes_gcm_dec_update_vaes_avx10_512(AES_GCM_KEY_AVX10(key),
+							  le_ctr, ghash_acc,
+							  src, dst, datalen);
+		else
+			aes_gcm_dec_update_vaes_avx10_256(AES_GCM_KEY_AVX10(key),
+							  le_ctr, ghash_acc,
+							  src, dst, datalen);
+	}
+}
+
+asmlinkage void
+aes_gcm_enc_final_vaes_avx10(const struct aes_gcm_key_avx10 *key,
+			     const u32 le_ctr[4], u8 ghash_acc[16],
+			     u64 total_aadlen, u64 total_datalen);
+
+/* __always_inline to optimize out the branches based on @flags */
+static __always_inline void
+aes_gcm_enc_final(const struct aes_gcm_key *key,
+		  const u32 le_ctr[4], u8 ghash_acc[16],
+		  u64 total_aadlen, u64 total_datalen, int flags)
+{
+	aes_gcm_enc_final_vaes_avx10(AES_GCM_KEY_AVX10(key),
+				     le_ctr, ghash_acc,
+				     total_aadlen, total_datalen);
+}
+
+asmlinkage bool __must_check
+aes_gcm_dec_final_vaes_avx10(const struct aes_gcm_key_avx10 *key,
+			     const u32 le_ctr[4], const u8 ghash_acc[16],
+			     u64 total_aadlen, u64 total_datalen,
+			     const u8 tag[16], int taglen);
+
+/* __always_inline to optimize out the branches based on @flags */
+static __always_inline bool __must_check
+aes_gcm_dec_final(const struct aes_gcm_key *key, const u32 le_ctr[4],
+		  u8 ghash_acc[16], u64 total_aadlen, u64 total_datalen,
+		  u8 tag[16], int taglen, int flags)
+{
+	return aes_gcm_dec_final_vaes_avx10(AES_GCM_KEY_AVX10(key),
+					    le_ctr, ghash_acc,
+					    total_aadlen, total_datalen,
+					    tag, taglen);
+}
+
+/*
+ * This is the setkey function for the x86_64 implementations of AES-GCM.  It
+ * saves the RFC4106 nonce if applicable, expands the AES key, and precomputes
+ * powers of the hash key.
+ *
+ * To comply with the crypto_aead API, this has to be usable in no-SIMD context.
+ * For that reason, this function includes a portable C implementation of the
+ * needed logic.  However, the portable C implementation is very slow, taking
+ * about the same time as encrypting 37 KB of data.  To be ready for users that
+ * may set a key even somewhat frequently, we therefore also include a SIMD
+ * assembly implementation, expanding the AES key using AES-NI and precomputing
+ * the hash key powers using PCLMULQDQ or VPCLMULQDQ.
+ */
+static int gcm_setkey(struct crypto_aead *tfm, const u8 *raw_key,
+		      unsigned int keylen, int flags)
+{
+	struct aes_gcm_key *key = aes_gcm_key_get(tfm, flags);
+	int err;
+
+	if (flags & FLAG_RFC4106) {
+		if (keylen < 4)
+			return -EINVAL;
+		keylen -= 4;
+		key->rfc4106_nonce = get_unaligned_be32(raw_key + keylen);
+	}
+
+	/* The assembly code assumes the following offsets. */
+	BUILD_BUG_ON(offsetof(struct aes_gcm_key_avx10, base.aes_key.key_enc) != 0);
+	BUILD_BUG_ON(offsetof(struct aes_gcm_key_avx10, base.aes_key.key_length) != 480);
+	BUILD_BUG_ON(offsetof(struct aes_gcm_key_avx10, h_powers) != 512);
+	BUILD_BUG_ON(offsetof(struct aes_gcm_key_avx10, padding) != 768);
+
+	if (likely(crypto_simd_usable())) {
+		err = aes_check_keylen(keylen);
+		if (err)
+			return err;
+		kernel_fpu_begin();
+		aesni_set_key(&key->aes_key, raw_key, keylen);
+		aes_gcm_precompute(key, flags);
+		kernel_fpu_end();
+	} else {
+		static const u8 x_to_the_minus1[16] __aligned(__alignof__(be128)) = {
+			[0] = 0xc2, [15] = 1
+		};
+		struct aes_gcm_key_avx10 *k = AES_GCM_KEY_AVX10(key);
+		be128 h1 = {};
+		be128 h;
+		int i;
+
+		err = aes_expandkey(&key->aes_key, raw_key, keylen);
+		if (err)
+			return err;
+
+		/* Encrypt the all-zeroes block to get the hash key H^1 */
+		aes_encrypt(&key->aes_key, (u8 *)&h1, (u8 *)&h1);
+
+		/* Compute H^1 * x^-1 */
+		h = h1;
+		gf128mul_lle(&h, (const be128 *)x_to_the_minus1);
+
+		/* Compute the needed key powers */
+		for (i = ARRAY_SIZE(k->h_powers) - 1; i >= 0; i--) {
+			k->h_powers[i][0] = be64_to_cpu(h.b);
+			k->h_powers[i][1] = be64_to_cpu(h.a);
+			gf128mul_lle(&h, &h1);
+		}
+		memset(k->padding, 0, sizeof(k->padding));
+	}
+	return 0;
+}
+
+/*
+ * Initialize @ghash_acc, then pass all @assoclen bytes of associated data
+ * (a.k.a. additional authenticated data) from @sg_src through the GHASH update
+ * assembly function.  kernel_fpu_begin() must have already been called.
+ */
+static void gcm_process_assoc(const struct aes_gcm_key *key, u8 ghash_acc[16],
+			      struct scatterlist *sg_src, unsigned int assoclen,
+			      int flags)
+{
+	struct scatter_walk walk;
+	/*
+	 * The assembly function requires that the length of any non-last
+	 * segment of associated data be a multiple of 16 bytes, so this
+	 * function does the buffering needed to achieve that.
+	 */
+	unsigned int pos = 0;
+	u8 buf[16];
+
+	memset(ghash_acc, 0, 16);
+	scatterwalk_start(&walk, sg_src);
+
+	while (assoclen) {
+		unsigned int len_this_page = scatterwalk_clamp(&walk, assoclen);
+		void *mapped = scatterwalk_map(&walk);
+		const void *src = mapped;
+		unsigned int len;
+
+		assoclen -= len_this_page;
+		scatterwalk_advance(&walk, len_this_page);
+		if (unlikely(pos)) {
+			len = min(len_this_page, 16 - pos);
+			memcpy(&buf[pos], src, len);
+			pos += len;
+			src += len;
+			len_this_page -= len;
+			if (pos < 16)
+				goto next;
+			aes_gcm_aad_update(key, ghash_acc, buf, 16, flags);
+			pos = 0;
+		}
+		len = len_this_page;
+		if (unlikely(assoclen)) /* Not the last segment yet? */
+			len = round_down(len, 16);
+		aes_gcm_aad_update(key, ghash_acc, src, len, flags);
+		src += len;
+		len_this_page -= len;
+		if (unlikely(len_this_page)) {
+			memcpy(buf, src, len_this_page);
+			pos = len_this_page;
+		}
+next:
+		scatterwalk_unmap(mapped);
+		scatterwalk_pagedone(&walk, 0, assoclen);
+		if (need_resched()) {
+			kernel_fpu_end();
+			kernel_fpu_begin();
+		}
+	}
+	if (unlikely(pos))
+		aes_gcm_aad_update(key, ghash_acc, buf, pos, flags);
+}
+
+
+/* __always_inline to optimize out the branches based on @flags */
+static __always_inline int
+gcm_crypt(struct aead_request *req, int flags)
+{
+	struct crypto_aead *tfm = crypto_aead_reqtfm(req);
+	const struct aes_gcm_key *key = aes_gcm_key_get(tfm, flags);
+	unsigned int assoclen = req->assoclen;
+	struct skcipher_walk walk;
+	unsigned int nbytes;
+	u8 ghash_acc[16]; /* GHASH accumulator */
+	u32 le_ctr[4]; /* Counter in little-endian format */
+	int taglen;
+	int err;
+
+	/* Initialize the counter and determine the associated data length. */
+	le_ctr[0] = 2;
+	if (flags & FLAG_RFC4106) {
+		if (unlikely(assoclen != 16 && assoclen != 20))
+			return -EINVAL;
+		assoclen -= 8;
+		le_ctr[1] = get_unaligned_be32(req->iv + 4);
+		le_ctr[2] = get_unaligned_be32(req->iv + 0);
+		le_ctr[3] = key->rfc4106_nonce; /* already byte-swapped */
+	} else {
+		le_ctr[1] = get_unaligned_be32(req->iv + 8);
+		le_ctr[2] = get_unaligned_be32(req->iv + 4);
+		le_ctr[3] = get_unaligned_be32(req->iv + 0);
+	}
+
+	/* Begin walking through the plaintext or ciphertext. */
+	if (flags & FLAG_ENC)
+		err = skcipher_walk_aead_encrypt(&walk, req, false);
+	else
+		err = skcipher_walk_aead_decrypt(&walk, req, false);
+
+	/*
+	 * Since the AES-GCM assembly code requires that at least three assembly
+	 * functions be called to process any message (this is needed to support
+	 * incremental updates cleanly), to reduce overhead we try to do all
+	 * three calls in the same kernel FPU section if possible.  We close the
+	 * section and start a new one if there are multiple data segments or if
+	 * rescheduling is needed while processing the associated data.
+	 */
+	kernel_fpu_begin();
+
+	/* Pass the associated data through GHASH. */
+	gcm_process_assoc(key, ghash_acc, req->src, assoclen, flags);
+
+	/* En/decrypt the data and pass the ciphertext through GHASH. */
+	while ((nbytes = walk.nbytes) != 0) {
+		if (unlikely(nbytes < walk.total)) {
+			/*
+			 * Non-last segment.  In this case, the assembly
+			 * function requires that the length be a multiple of 16
+			 * (AES_BLOCK_SIZE) bytes.  The needed buffering of up
+			 * to 16 bytes is handled by the skcipher_walk.  Here we
+			 * just need to round down to a multiple of 16.
+			 */
+			nbytes = round_down(nbytes, AES_BLOCK_SIZE);
+			aes_gcm_update(key, le_ctr, ghash_acc,
+				       walk.src.virt.addr, walk.dst.virt.addr,
+				       nbytes, flags);
+			le_ctr[0] += nbytes / AES_BLOCK_SIZE;
+			kernel_fpu_end();
+			err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
+			kernel_fpu_begin();
+		} else {
+			/* Last segment: process all remaining data. */
+			aes_gcm_update(key, le_ctr, ghash_acc,
+				       walk.src.virt.addr, walk.dst.virt.addr,
+				       nbytes, flags);
+			err = skcipher_walk_done(&walk, 0);
+			/*
+			 * The low word of the counter isn't used by the
+			 * finalize, so there's no need to increment it here.
+			 */
+		}
+	}
+	if (err)
+		goto out;
+
+	/* Finalize */
+	taglen = crypto_aead_authsize(tfm);
+	if (flags & FLAG_ENC) {
+		/* Finish computing the auth tag. */
+		aes_gcm_enc_final(key, le_ctr, ghash_acc, assoclen,
+				  req->cryptlen, flags);
+
+		/* Store the computed auth tag in the dst scatterlist. */
+		scatterwalk_map_and_copy(ghash_acc, req->dst, req->assoclen +
+					 req->cryptlen, taglen, 1);
+	} else {
+		unsigned int datalen = req->cryptlen - taglen;
+		u8 tag[16];
+
+		/* Get the transmitted auth tag from the src scatterlist. */
+		scatterwalk_map_and_copy(tag, req->src, req->assoclen + datalen,
+					 taglen, 0);
+		/*
+		 * Finish computing the auth tag and compare it to the
+		 * transmitted one.  The assembly function does the actual tag
+		 * comparison.  Here, just check the boolean result.
+		 */
+		if (!aes_gcm_dec_final(key, le_ctr, ghash_acc, assoclen,
+				       datalen, tag, taglen, flags))
+			err = -EBADMSG;
+	}
+out:
+	kernel_fpu_end();
+	return err;
+}
+
+#define DEFINE_GCM_ALGS(suffix, flags, generic_driver_name, rfc_driver_name,   \
+			ctxsize, priority)				       \
+									       \
+static int gcm_setkey_##suffix(struct crypto_aead *tfm, const u8 *raw_key,     \
+			    unsigned int keylen)			       \
+{									       \
+	return gcm_setkey(tfm, raw_key, keylen, (flags));		       \
+}									       \
+									       \
+static int gcm_encrypt_##suffix(struct aead_request *req)		       \
+{									       \
+	return gcm_crypt(req, (flags) | FLAG_ENC);			       \
+}									       \
+									       \
+static int gcm_decrypt_##suffix(struct aead_request *req)		       \
+{									       \
+	return gcm_crypt(req, (flags));					       \
+}									       \
+									       \
+static int rfc4106_setkey_##suffix(struct crypto_aead *tfm, const u8 *raw_key, \
+				unsigned int keylen)			       \
+{									       \
+	return gcm_setkey(tfm, raw_key, keylen, (flags) | FLAG_RFC4106);       \
+}									       \
+									       \
+static int rfc4106_encrypt_##suffix(struct aead_request *req)		       \
+{									       \
+	return gcm_crypt(req, (flags) | FLAG_RFC4106 | FLAG_ENC);	       \
+}									       \
+									       \
+static int rfc4106_decrypt_##suffix(struct aead_request *req)		       \
+{									       \
+	return gcm_crypt(req, (flags) | FLAG_RFC4106);			       \
+}									       \
+									       \
+static struct aead_alg aes_gcm_algs_##suffix[] = { {			       \
+	.setkey			= gcm_setkey_##suffix,			       \
+	.setauthsize		= generic_gcmaes_set_authsize,		       \
+	.encrypt		= gcm_encrypt_##suffix,			       \
+	.decrypt		= gcm_decrypt_##suffix,			       \
+	.ivsize			= GCM_AES_IV_SIZE,			       \
+	.chunksize		= AES_BLOCK_SIZE,			       \
+	.maxauthsize		= 16,					       \
+	.base = {							       \
+		.cra_name		= "__gcm(aes)",			       \
+		.cra_driver_name	= "__" generic_driver_name,	       \
+		.cra_priority		= (priority),			       \
+		.cra_flags		= CRYPTO_ALG_INTERNAL,		       \
+		.cra_blocksize		= 1,				       \
+		.cra_ctxsize		= (ctxsize),			       \
+		.cra_module		= THIS_MODULE,			       \
+	},								       \
+}, {									       \
+	.setkey			= rfc4106_setkey_##suffix,		       \
+	.setauthsize		= common_rfc4106_set_authsize,		       \
+	.encrypt		= rfc4106_encrypt_##suffix,		       \
+	.decrypt		= rfc4106_decrypt_##suffix,		       \
+	.ivsize			= GCM_RFC4106_IV_SIZE,			       \
+	.chunksize		= AES_BLOCK_SIZE,			       \
+	.maxauthsize		= 16,					       \
+	.base = {							       \
+		.cra_name		= "__rfc4106(gcm(aes))",	       \
+		.cra_driver_name	= "__" rfc_driver_name,		       \
+		.cra_priority		= (priority),			       \
+		.cra_flags		= CRYPTO_ALG_INTERNAL,		       \
+		.cra_blocksize		= 1,				       \
+		.cra_ctxsize		= (ctxsize),			       \
+		.cra_module		= THIS_MODULE,			       \
+	},								       \
+} };									       \
+									       \
+static struct simd_aead_alg *aes_gcm_simdalgs_##suffix[2]		       \
+
+/* aes_gcm_algs_vaes_avx10_256 */
+DEFINE_GCM_ALGS(vaes_avx10_256, 0,
+		"generic-gcm-vaes-avx10_256", "rfc4106-gcm-vaes-avx10_256",
+		AES_GCM_KEY_AVX10_SIZE, 700);
+
+/* aes_gcm_algs_vaes_avx10_512 */
+DEFINE_GCM_ALGS(vaes_avx10_512, FLAG_AVX10_512,
+		"generic-gcm-vaes-avx10_512", "rfc4106-gcm-vaes-avx10_512",
+		AES_GCM_KEY_AVX10_SIZE, 800);
+#endif /* CONFIG_AS_VAES && CONFIG_AS_VPCLMULQDQ */
 
 /*
  * 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.
+ * zmm registers (512-bit vectors) are used.  On these CPUs, the AES mode
+ * implementations with zmm registers won't be used by default.  Implementations
+ * with ymm registers (256-bit vectors) will be used by default instead.
  */
 static const struct x86_cpu_id zmm_exclusion_list[] = {
 	X86_MATCH_VFM(INTEL_SKYLAKE_X,		0),
@@ -1236,7 +1730,7 @@ static const struct x86_cpu_id zmm_exclusion_list[] = {
 	{},
 };
 
-static int __init register_xts_algs(void)
+static int __init register_avx_algs(void)
 {
 	int err;
 
@@ -1269,19 +1763,34 @@ static int __init register_xts_algs(void)
 					     &aes_xts_simdalg_vaes_avx10_256);
 	if (err)
 		return err;
+	err = simd_register_aeads_compat(aes_gcm_algs_vaes_avx10_256,
+					 ARRAY_SIZE(aes_gcm_algs_vaes_avx10_256),
+					 aes_gcm_simdalgs_vaes_avx10_256);
+	if (err)
+		return err;
+
+	if (x86_match_cpu(zmm_exclusion_list)) {
+		int i;
 
-	if (x86_match_cpu(zmm_exclusion_list))
 		aes_xts_alg_vaes_avx10_512.base.cra_priority = 1;
+		for (i = 0; i < ARRAY_SIZE(aes_gcm_algs_vaes_avx10_512); i++)
+			aes_gcm_algs_vaes_avx10_512[i].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;
+	err = simd_register_aeads_compat(aes_gcm_algs_vaes_avx10_512,
+					 ARRAY_SIZE(aes_gcm_algs_vaes_avx10_512),
+					 aes_gcm_simdalgs_vaes_avx10_512);
+	if (err)
+		return err;
 #endif /* CONFIG_AS_VAES && CONFIG_AS_VPCLMULQDQ */
 	return 0;
 }
 
-static void unregister_xts_algs(void)
+static void unregister_avx_algs(void)
 {
 	if (aes_xts_simdalg_aesni_avx)
 		simd_unregister_skciphers(&aes_xts_alg_aesni_avx, 1,
@@ -1293,18 +1802,26 @@ static void unregister_xts_algs(void)
 	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_gcm_simdalgs_vaes_avx10_256[0])
+		simd_unregister_aeads(aes_gcm_algs_vaes_avx10_256,
+				      ARRAY_SIZE(aes_gcm_algs_vaes_avx10_256),
+				      aes_gcm_simdalgs_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);
+	if (aes_gcm_simdalgs_vaes_avx10_512[0])
+		simd_unregister_aeads(aes_gcm_algs_vaes_avx10_512,
+				      ARRAY_SIZE(aes_gcm_algs_vaes_avx10_512),
+				      aes_gcm_simdalgs_vaes_avx10_512);
 #endif
 }
 #else /* CONFIG_X86_64 */
-static int __init register_xts_algs(void)
+static int __init register_avx_algs(void)
 {
 	return 0;
 }
 
-static void unregister_xts_algs(void)
+static void unregister_avx_algs(void)
 {
 }
 #endif /* !CONFIG_X86_64 */
@@ -1447,14 +1964,14 @@ static int __init aesni_init(void)
 		goto unregister_aeads;
 #endif /* CONFIG_X86_64 */
 
-	err = register_xts_algs();
+	err = register_avx_algs();
 	if (err)
-		goto unregister_xts;
+		goto unregister_avx;
 
 	return 0;
 
-unregister_xts:
-	unregister_xts_algs();
+unregister_avx:
+	unregister_avx_algs();
 #ifdef CONFIG_X86_64
 	if (aesni_simd_xctr)
 		simd_unregister_skciphers(&aesni_xctr, 1, &aesni_simd_xctr);
@@ -1482,7 +1999,7 @@ static void __exit aesni_exit(void)
 	if (boot_cpu_has(X86_FEATURE_AVX))
 		simd_unregister_skciphers(&aesni_xctr, 1, &aesni_simd_xctr);
 #endif /* CONFIG_X86_64 */
-	unregister_xts_algs();
+	unregister_avx_algs();
 }
 
 late_initcall(aesni_init);