KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

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 <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 88 insertions, 0 deletions

diff --git a/Documentation/crypto/libcrypto-hash.rst b/Documentation/crypto/libcrypto-hash.rst
new file mode 100644
index 000000000..fa4c54236
--- /dev/null
+++ b/Documentation/crypto/libcrypto-hash.rst
@@ -0,0 +1,88 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Hash functions, MACs, and XOFs
+==============================
+
+AES-CMAC and AES-XCBC-MAC
+-------------------------
+
+This API provides support for the AES-CMAC and AES-XCBC-MAC message
+authentication codes.
+
+.. kernel-doc:: include/crypto/aes-cbc-macs.h
+
+BLAKE2b
+-------
+
+This API provides support for the BLAKE2b cryptographic hash function.
+
+.. kernel-doc:: include/crypto/blake2b.h
+
+BLAKE2s
+-------
+
+This API provides support for the BLAKE2s cryptographic hash function.
+
+.. kernel-doc:: include/crypto/blake2s.h
+
+GHASH and POLYVAL
+-----------------
+
+This API provides support for the GHASH and POLYVAL universal hash functions.
+These algorithms are used only as internal components of other algorithms.
+
+.. kernel-doc:: include/crypto/gf128hash.h
+
+MD5
+---
+
+This API provides support for the MD5 cryptographic hash function and HMAC-MD5.
+This algorithm is obsolete and is supported only for backwards compatibility.
+
+.. kernel-doc:: include/crypto/md5.h
+
+NH
+--
+
+This API provides support for the NH universal hash function.  This algorithm is
+used only as an internal component of other algorithms.
+
+.. kernel-doc:: include/crypto/nh.h
+
+Poly1305
+--------
+
+This API provides support for the Poly1305 universal hash function.  This
+algorithm is used only as an internal component of other algorithms.
+
+.. kernel-doc:: include/crypto/poly1305.h
+
+SHA-1
+-----
+
+This API provides support for the SHA-1 cryptographic hash function and
+HMAC-SHA1.  This algorithm is obsolete and is supported only for backwards
+compatibility.
+
+.. kernel-doc:: include/crypto/sha1.h
+
+SHA-2
+-----
+
+This API provides support for the SHA-2 family of cryptographic hash functions,
+including SHA-224, SHA-256, SHA-384, and SHA-512.  This also includes their
+corresponding HMACs: HMAC-SHA224, HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512.
+
+.. kernel-doc:: include/crypto/sha2.h
+
+SHA-3
+-----
+
+The SHA-3 API is documented in :ref:`sha3`.
+
+SM3
+---
+
+This API provides support for the SM3 cryptographic hash function.
+
+.. kernel-doc:: include/crypto/sm3.h