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, 54 insertions, 0 deletions

diff --git a/tools/bootconfig/include/linux/bootconfig.h b/tools/bootconfig/include/linux/bootconfig.h
new file mode 100644
index 000000000..6784296a0
--- /dev/null
+++ b/tools/bootconfig/include/linux/bootconfig.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _BOOTCONFIG_LINUX_BOOTCONFIG_H
+#define _BOOTCONFIG_LINUX_BOOTCONFIG_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+
+
+#ifndef fallthrough
+# define fallthrough
+#endif
+
+#define WARN_ON(cond)	\
+	((cond) ? printf("Internal warning(%s:%d, %s): %s\n",	\
+			__FILE__, __LINE__, __func__, #cond) : 0)
+
+#define unlikely(cond)	(cond)
+
+/* Copied from lib/string.c */
+static inline char *skip_spaces(const char *str)
+{
+	while (isspace(*str))
+		++str;
+	return (char *)str;
+}
+
+static inline char *strim(char *s)
+{
+	size_t size;
+	char *end;
+
+	size = strlen(s);
+	if (!size)
+		return s;
+
+	end = s + size - 1;
+	while (end >= s && isspace(*end))
+		end--;
+	*(end + 1) = '\0';
+
+	return skip_spaces(s);
+}
+
+#define __init
+#define __initdata
+
+#include "../../../../include/linux/bootconfig.h"
+
+#endif