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, 29 insertions, 0 deletions

diff --git a/arch/mips/ralink/bootrom.c b/arch/mips/ralink/bootrom.c
new file mode 100644
index 000000000..8c8cc0a81
--- /dev/null
+++ b/arch/mips/ralink/bootrom.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#define BOOTROM_OFFSET	0x10118000
+#define BOOTROM_SIZE	0x8000
+
+static void __iomem *membase = (void __iomem *) KSEG1ADDR(BOOTROM_OFFSET);
+
+static int bootrom_show(struct seq_file *s, void *unused)
+{
+	seq_write(s, membase, BOOTROM_SIZE);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(bootrom);
+
+static int __init bootrom_setup(void)
+{
+	debugfs_create_file("bootrom", 0444, NULL, NULL, &bootrom_fops);
+	return 0;
+}
+
+postcore_initcall(bootrom_setup);