lib/crypto: riscv/ghash: Migrate optimized code into library

Remove the "ghash-riscv64-zvkg" crypto_shash algorithm.  Move the
corresponding assembly code into lib/crypto/, modify it to take the
length in blocks instead of bytes, and wire it up to the GHASH library.

This makes the GHASH library be optimized with the RISC-V Vector
Cryptography Extension.  It also greatly reduces the amount of
riscv-specific glue code that is needed, and it fixes the issue where
this optimized GHASH code was disabled by default.

Note that this RISC-V code has multiple opportunities for improvement,
such as adding more parallelism, providing an optimized multiplication
function, and directly supporting POLYVAL.  But for now, this commit
simply tweaks ghash_zvkg() slightly to make it compatible with the
library, then wires it up to ghash_blocks_arch().

ghash_preparekey_arch() is also implemented to store the copy of the raw
key needed by the vghsh.vv instruction.

Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-13-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

lib/crypto/Kconfig

@@ -122,6 +122,8 @@ config CRYPTO_LIB_GF128HASH_ARCH
 	default y if ARM && KERNEL_MODE_NEON
 	default y if ARM64
 	default y if PPC64 && VSX
+	default y if RISCV && 64BIT && TOOLCHAIN_HAS_VECTOR_CRYPTO && \
+		     RISCV_EFFICIENT_VECTOR_UNALIGNED_ACCESS
 	default y if X86_64
 
 config CRYPTO_LIB_MD5

lib/crypto/Makefile

@@ -173,6 +173,7 @@ targets += powerpc/ghashp8-ppc.S
 OBJECT_FILES_NON_STANDARD_powerpc/ghashp8-ppc.o := y
 endif
 
+libgf128hash-$(CONFIG_RISCV) += riscv/ghash-riscv64-zvkg.o
 libgf128hash-$(CONFIG_X86) += x86/polyval-pclmul-avx.o
 endif # CONFIG_CRYPTO_LIB_GF128HASH_ARCH
 

lib/crypto/riscv/gf128hash.h

@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * GHASH, RISC-V optimized
+ *
+ * Copyright (C) 2023 VRULL GmbH
+ * Copyright (C) 2023 SiFive, Inc.
+ * Copyright 2026 Google LLC
+ */
+
+#include <asm/simd.h>
+#include <asm/vector.h>
+
+static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_zvkg);
+
+asmlinkage void ghash_zvkg(u8 accumulator[GHASH_BLOCK_SIZE],
+			   const u8 key[GHASH_BLOCK_SIZE],
+			   const u8 *data, size_t nblocks);
+
+#define ghash_preparekey_arch ghash_preparekey_arch
+static void ghash_preparekey_arch(struct ghash_key *key,
+				  const u8 raw_key[GHASH_BLOCK_SIZE])
+{
+	/* Save key in POLYVAL format for fallback */
+	ghash_key_to_polyval(raw_key, &key->h);
+
+	/* Save key in GHASH format for zvkg */
+	memcpy(key->h_raw, raw_key, GHASH_BLOCK_SIZE);
+}
+
+#define ghash_blocks_arch ghash_blocks_arch
+static void ghash_blocks_arch(struct polyval_elem *acc,
+			      const struct ghash_key *key,
+			      const u8 *data, size_t nblocks)
+{
+	if (static_branch_likely(&have_zvkg) && likely(may_use_simd())) {
+		u8 ghash_acc[GHASH_BLOCK_SIZE];
+
+		polyval_acc_to_ghash(acc, ghash_acc);
+
+		kernel_vector_begin();
+		ghash_zvkg(ghash_acc, key->h_raw, data, nblocks);
+		kernel_vector_end();
+
+		ghash_acc_to_polyval(ghash_acc, acc);
+		memzero_explicit(ghash_acc, sizeof(ghash_acc));
+	} else {
+		ghash_blocks_generic(acc, &key->h, data, nblocks);
+	}
+}
+
+#define gf128hash_mod_init_arch gf128hash_mod_init_arch
+static void gf128hash_mod_init_arch(void)
+{
+	if (riscv_isa_extension_available(NULL, ZVKG) &&
+	    riscv_vector_vlen() >= 128)
+		static_branch_enable(&have_zvkg);
+}

lib/crypto/riscv/ghash-riscv64-zvkg.S

@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: Apache-2.0 OR BSD-2-Clause */
+//
+// This file is dual-licensed, meaning that you can use it under your
+// choice of either of the following two licenses:
+//
+// Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
+//
+// Licensed under the Apache License 2.0 (the "License"). You can obtain
+// a copy in the file LICENSE in the source distribution or at
+// https://www.openssl.org/source/license.html
+//
+// or
+//
+// Copyright (c) 2023, Christoph Müllner <christoph.muellner@vrull.eu>
+// Copyright (c) 2023, Jerry Shih <jerry.shih@sifive.com>
+// Copyright 2024 Google LLC
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions
+// are met:
+// 1. Redistributions of source code must retain the above copyright
+//    notice, this list of conditions and the following disclaimer.
+// 2. Redistributions in binary form must reproduce the above copyright
+//    notice, this list of conditions and the following disclaimer in the
+//    documentation and/or other materials provided with the distribution.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+// The generated code of this file depends on the following RISC-V extensions:
+// - RV64I
+// - RISC-V Vector ('V') with VLEN >= 128
+// - RISC-V Vector GCM/GMAC extension ('Zvkg')
+
+#include <linux/linkage.h>
+
+.text
+.option arch, +zvkg
+
+#define ACCUMULATOR	a0
+#define KEY		a1
+#define DATA		a2
+#define NBLOCKS		a3
+
+// void ghash_zvkg(u8 accumulator[GHASH_BLOCK_SIZE],
+//		   const u8 key[GHASH_BLOCK_SIZE],
+//		   const u8 *data, size_t nblocks);
+//
+// |nblocks| must be nonzero.
+SYM_FUNC_START(ghash_zvkg)
+	vsetivli	zero, 4, e32, m1, ta, ma
+	vle32.v		v1, (ACCUMULATOR)
+	vle32.v		v2, (KEY)
+.Lnext_block:
+	vle32.v		v3, (DATA)
+	vghsh.vv	v1, v2, v3
+	addi		DATA, DATA, 16
+	addi		NBLOCKS, NBLOCKS, -1
+	bnez		NBLOCKS, .Lnext_block
+
+	vse32.v		v1, (ACCUMULATOR)
+	ret
+SYM_FUNC_END(ghash_zvkg)