From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- include/crypto/utils.h | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 include/crypto/utils.h (limited to 'include/crypto/utils.h') diff --git a/include/crypto/utils.h b/include/crypto/utils.h new file mode 100644 index 000000000..2594f4577 --- /dev/null +++ b/include/crypto/utils.h @@ -0,0 +1,73 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Cryptographic utilities + * + * Copyright (c) 2023 Herbert Xu + */ +#ifndef _CRYPTO_UTILS_H +#define _CRYPTO_UTILS_H + +#include +#include +#include + +void __crypto_xor(u8 *dst, const u8 *src1, const u8 *src2, unsigned int size); + +static inline void crypto_xor(u8 *dst, const u8 *src, unsigned int size) +{ + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && + __builtin_constant_p(size) && + (size % sizeof(unsigned long)) == 0) { + unsigned long *d = (unsigned long *)dst; + unsigned long *s = (unsigned long *)src; + unsigned long l; + + while (size > 0) { + l = get_unaligned(d) ^ get_unaligned(s++); + put_unaligned(l, d++); + size -= sizeof(unsigned long); + } + } else { + __crypto_xor(dst, dst, src, size); + } +} + +static inline void crypto_xor_cpy(u8 *dst, const u8 *src1, const u8 *src2, + unsigned int size) +{ + if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && + __builtin_constant_p(size) && + (size % sizeof(unsigned long)) == 0) { + unsigned long *d = (unsigned long *)dst; + unsigned long *s1 = (unsigned long *)src1; + unsigned long *s2 = (unsigned long *)src2; + unsigned long l; + + while (size > 0) { + l = get_unaligned(s1++) ^ get_unaligned(s2++); + put_unaligned(l, d++); + size -= sizeof(unsigned long); + } + } else { + __crypto_xor(dst, src1, src2, size); + } +} + +noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size); + +/** + * crypto_memneq - Compare two areas of memory without leaking + * timing information. + * + * @a: One area of memory + * @b: Another area of memory + * @size: The size of the area. + * + * Returns 0 when data is equal, 1 otherwise. + */ +static inline int crypto_memneq(const void *a, const void *b, size_t size) +{ + return __crypto_memneq(a, b, size) != 0UL ? 1 : 0; +} + +#endif /* _CRYPTO_UTILS_H */ -- cgit v1.3.1