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, 40 insertions, 0 deletions

diff --git a/include/crypto/internal/rng.h b/include/crypto/internal/rng.h
new file mode 100644
index 000000000..e0711b6a5
--- /dev/null
+++ b/include/crypto/internal/rng.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * RNG: Random Number Generator  algorithms under the crypto API
+ *
+ * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
+ * Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#ifndef _CRYPTO_INTERNAL_RNG_H
+#define _CRYPTO_INTERNAL_RNG_H
+
+#include <crypto/algapi.h>
+#include <crypto/rng.h>
+
+int crypto_register_rng(struct rng_alg *alg);
+void crypto_unregister_rng(struct rng_alg *alg);
+int crypto_register_rngs(struct rng_alg *algs, int count);
+void crypto_unregister_rngs(struct rng_alg *algs, int count);
+
+#if defined(CONFIG_CRYPTO_RNG) || defined(CONFIG_CRYPTO_RNG_MODULE)
+int crypto_del_default_rng(void);
+#else
+static inline int crypto_del_default_rng(void)
+{
+	return 0;
+}
+#endif
+
+static inline void *crypto_rng_ctx(struct crypto_rng *tfm)
+{
+	return crypto_tfm_ctx(&tfm->base);
+}
+
+static inline void crypto_rng_set_entropy(struct crypto_rng *tfm,
+					  const u8 *data, unsigned int len)
+{
+	crypto_rng_alg(tfm)->set_ent(tfm, data, len);
+}
+
+#endif