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, 36 insertions, 0 deletions

diff --git a/tools/include/nolibc/assert.h b/tools/include/nolibc/assert.h
new file mode 100644
index 000000000..84ff8ad9a
--- /dev/null
+++ b/tools/include/nolibc/assert.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
+/*
+ * Assert for NOLIBC
+ * Copyright (C) 2026 Thomas Weißschuh <linux@weissschuh.net>
+ */
+
+/* make sure to include all global symbols */
+#include "nolibc.h"
+
+#ifndef _NOLIBC_ASSERT_H
+#define _NOLIBC_ASSERT_H
+
+#include "errno.h"
+#include "stdio.h"
+#include "stdlib.h"
+
+#endif /* _NOLIBC_ASSERT_H */
+
+/* NDEBUG needs to be evaluated on *each* inclusion */
+#ifdef assert
+#undef assert
+#endif
+
+#ifndef NDEBUG
+#define assert(expr)									\
+({											\
+	if (!(expr)) {									\
+		fprintf(stderr, "%s: %s:%d: %s: Assertion `%s' failed.\n",		\
+			program_invocation_short_name, __FILE__, __LINE__, __func__,	\
+			#expr);								\
+		abort();								\
+	}										\
+})
+#else
+#define assert(expr) ((void)0)
+#endif