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/init/version.c b/init/version.c
new file mode 100644
index 000000000..94c96f6fb
--- /dev/null
+++ b/init/version.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/init/version.c
+ *
+ *  Copyright (C) 1992  Theodore Ts'o
+ *
+ *  May be freely distributed as part of Linux.
+ */
+
+#include <generated/compile.h>
+#include <linux/build-salt.h>
+#include <linux/elfnote-lto.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/printk.h>
+#include <linux/uts.h>
+#include <linux/utsname.h>
+#include <linux/proc_ns.h>
+
+static int __init early_hostname(char *arg)
+{
+	size_t bufsize = sizeof(init_uts_ns.name.nodename);
+	size_t maxlen  = bufsize - 1;
+	ssize_t arglen;
+
+	arglen = strscpy(init_uts_ns.name.nodename, arg, bufsize);
+	if (arglen < 0) {
+		pr_warn("hostname parameter exceeds %zd characters and will be truncated",
+			maxlen);
+	}
+	return 0;
+}
+early_param("hostname", early_hostname);
+
+const char linux_proc_banner[] =
+	"%s version %s"
+	" (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ")"
+	" (" LINUX_COMPILER ") %s\n";
+
+BUILD_SALT;
+BUILD_LTO_INFO;
+
+/*
+ * init_uts_ns and linux_banner contain the build version and timestamp,
+ * which are really fixed at the very last step of build process.
+ * They are compiled with __weak first, and without __weak later.
+ */
+
+struct uts_namespace init_uts_ns __weak;
+const char linux_banner[] __weak;
+
+#include "version-timestamp.c"
+
+EXPORT_SYMBOL_GPL(init_uts_ns);