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, 25 insertions, 0 deletions

diff --git a/include/crypto/twofish.h b/include/crypto/twofish.h
new file mode 100644
index 000000000..f6b307a58
--- /dev/null
+++ b/include/crypto/twofish.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _CRYPTO_TWOFISH_H
+#define _CRYPTO_TWOFISH_H
+
+#include <linux/types.h>
+
+#define TF_MIN_KEY_SIZE 16
+#define TF_MAX_KEY_SIZE 32
+#define TF_BLOCK_SIZE 16
+
+struct crypto_tfm;
+
+/* Structure for an expanded Twofish key.  s contains the key-dependent
+ * S-boxes composed with the MDS matrix; w contains the eight "whitening"
+ * subkeys, K[0] through K[7].	k holds the remaining, "round" subkeys.  Note
+ * that k[i] corresponds to what the Twofish paper calls K[i+8]. */
+struct twofish_ctx {
+	u32 s[4][256], w[8], k[32];
+};
+
+int __twofish_setkey(struct twofish_ctx *ctx, const u8 *key,
+		     unsigned int key_len);
+int twofish_setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int key_len);
+
+#endif