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/powerpc/boot/cuboot.c b/arch/powerpc/boot/cuboot.c
new file mode 100644
index 000000000..7f186658f
--- /dev/null
+++ b/arch/powerpc/boot/cuboot.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Compatibility for old (not device tree aware) U-Boot versions
+ *
+ * Author: Scott Wood <scottwood@freescale.com>
+ * Consolidated using macros by David Gibson <david@gibson.dropbear.id.au>
+ *
+ * Copyright 2007 David Gibson, IBM Corporation.
+ * Copyright (c) 2007 Freescale Semiconductor, Inc.
+ */
+
+#include "ops.h"
+#include "stdio.h"
+
+#include "ppcboot.h"
+
+void cuboot_init(unsigned long r4, unsigned long r5,
+		 unsigned long r6, unsigned long r7,
+		 unsigned long end_of_ram)
+{
+	unsigned long avail_ram = end_of_ram - (unsigned long)_end;
+
+	loader_info.initrd_addr = r4;
+	loader_info.initrd_size = r4 ? r5 - r4 : 0;
+	loader_info.cmdline = (char *)r6;
+	loader_info.cmdline_len = r7 - r6;
+
+	simple_alloc_init(_end, avail_ram - 1024*1024, 32, 64);
+}