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, 64 insertions, 0 deletions

diff --git a/include/crypto/gcm.h b/include/crypto/gcm.h
new file mode 100644
index 000000000..154038ca7
--- /dev/null
+++ b/include/crypto/gcm.h
@@ -0,0 +1,64 @@
+#ifndef _CRYPTO_GCM_H
+#define _CRYPTO_GCM_H
+
+#include <linux/errno.h>
+
+#define GCM_AES_IV_SIZE 12
+#define GCM_RFC4106_IV_SIZE 8
+#define GCM_RFC4543_IV_SIZE 8
+
+/*
+ * validate authentication tag for GCM
+ */
+static inline int crypto_gcm_check_authsize(size_t authsize)
+{
+	switch (authsize) {
+	case 4:
+	case 8:
+	case 12:
+	case 13:
+	case 14:
+	case 15:
+	case 16:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * validate authentication tag for RFC4106
+ */
+static inline int crypto_rfc4106_check_authsize(size_t authsize)
+{
+	switch (authsize) {
+	case 8:
+	case 12:
+	case 16:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * validate assoclen for RFC4106/RFC4543
+ */
+static inline int crypto_ipsec_check_assoclen(unsigned int assoclen)
+{
+	switch (assoclen) {
+	case 16:
+	case 20:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+#endif