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, 121 insertions, 0 deletions

diff --git a/scripts/kconfig/util.c b/scripts/kconfig/util.c
new file mode 100644
index 000000000..0809aa061
--- /dev/null
+++ b/scripts/kconfig/util.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2002-2005 Roman Zippel <zippel@linux-m68k.org>
+ * Copyright (C) 2002-2005 Sam Ravnborg <sam@ravnborg.org>
+ */
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <hash.h>
+#include <hashtable.h>
+#include <xalloc.h>
+#include "lkc.h"
+
+/* hash table of all parsed Kconfig files */
+static HASHTABLE_DEFINE(file_hashtable, 1U << 11);
+
+struct file {
+	struct hlist_node node;
+	struct {
+		const char *name;
+		int lineno;
+	} parent;
+	char name[];
+};
+
+static void die_duplicated_include(struct file *file,
+				   const char *parent, int lineno)
+{
+	fprintf(stderr,
+		"%s:%d: error: repeated inclusion of %s\n"
+		"%s:%d: note: location of first inclusion of %s\n",
+		parent, lineno, file->name,
+		file->parent.name, file->parent.lineno, file->name);
+	exit(1);
+}
+
+/* file already present in list? If not add it */
+const char *file_lookup(const char *name,
+			const char *parent_name, int parent_lineno)
+{
+	const char *parent = NULL;
+	struct file *file;
+	size_t len;
+	int hash = hash_str(name);
+
+	if (parent_name)
+		parent = file_lookup(parent_name, NULL, 0);
+
+	hash_for_each_possible(file_hashtable, file, node, hash)
+		if (!strcmp(name, file->name)) {
+			if (!parent_name)
+				return file->name;
+			die_duplicated_include(file, parent, parent_lineno);
+		}
+
+	len = strlen(name);
+	file = xmalloc(sizeof(*file) + len + 1);
+	memset(file, 0, sizeof(*file));
+	memcpy(file->name, name, len);
+	file->name[len] = '\0';
+	file->parent.name = parent;
+	file->parent.lineno = parent_lineno;
+
+	hash_add(file_hashtable, &file->node, hash);
+
+	str_printf(&autoconf_cmd, "\t%s \\\n", name);
+
+	return file->name;
+}
+
+/* Allocate initial growable string */
+struct gstr str_new(void)
+{
+	struct gstr gs;
+	gs.s = xmalloc(sizeof(char) * 64);
+	gs.len = 64;
+	gs.max_width = 0;
+	strcpy(gs.s, "\0");
+	return gs;
+}
+
+/* Free storage for growable string */
+void str_free(struct gstr *gs)
+{
+	free(gs->s);
+	gs->s = NULL;
+	gs->len = 0;
+}
+
+/* Append to growable string */
+void str_append(struct gstr *gs, const char *s)
+{
+	size_t l;
+	if (s) {
+		l = strlen(gs->s) + strlen(s) + 1;
+		if (l > gs->len) {
+			gs->s = xrealloc(gs->s, l);
+			gs->len = l;
+		}
+		strcat(gs->s, s);
+	}
+}
+
+/* Append printf formatted string to growable string */
+void str_printf(struct gstr *gs, const char *fmt, ...)
+{
+	va_list ap;
+	char s[10000]; /* big enough... */
+	va_start(ap, fmt);
+	vsnprintf(s, sizeof(s), fmt, ap);
+	str_append(gs, s);
+	va_end(ap);
+}
+
+/* Retrieve value of growable string */
+char *str_get(const struct gstr *gs)
+{
+	return gs->s;
+}