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, 87 insertions, 0 deletions

diff --git a/arch/m68k/coldfire/firebee.c b/arch/m68k/coldfire/firebee.c
new file mode 100644
index 000000000..3b9d4fc6f
--- /dev/null
+++ b/arch/m68k/coldfire/firebee.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/***************************************************************************/
+
+/*
+ *	firebee.c -- extra startup code support for the FireBee boards
+ *
+ *	Copyright (C) 2011, Greg Ungerer (gerg@snapgear.com)
+ */
+
+/***************************************************************************/
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/platform_device.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/partitions.h>
+#include <linux/mtd/physmap.h>
+#include <asm/coldfire.h>
+#include <asm/mcfsim.h>
+
+/***************************************************************************/
+
+/*
+ *	8MB of NOR flash fitted to the FireBee board.
+ */
+#define	FLASH_PHYS_ADDR		0xe0000000	/* Physical address of flash */
+#define	FLASH_PHYS_SIZE		0x00800000	/* Size of flash */
+
+#define	PART_BOOT_START		0x00000000	/* Start at bottom of flash */
+#define	PART_BOOT_SIZE		0x00040000	/* 256k in size */
+#define	PART_IMAGE_START	0x00040000	/* Start after boot loader */
+#define	PART_IMAGE_SIZE		0x006c0000	/* Most of flash */
+#define	PART_FPGA_START		0x00700000	/* Start at offset 7MB */
+#define	PART_FPGA_SIZE		0x00100000	/* 1MB in size */
+
+static struct mtd_partition firebee_flash_parts[] = {
+	{
+		.name	= "dBUG",
+		.offset	= PART_BOOT_START,
+		.size	= PART_BOOT_SIZE,
+	},
+	{
+		.name	= "FPGA",
+		.offset	= PART_FPGA_START,
+		.size	= PART_FPGA_SIZE,
+	},
+	{
+		.name	= "image",
+		.offset	= PART_IMAGE_START,
+		.size	= PART_IMAGE_SIZE,
+	},
+};
+
+static struct physmap_flash_data firebee_flash_data = {
+	.width		= 2,
+	.nr_parts	= ARRAY_SIZE(firebee_flash_parts),
+	.parts		= firebee_flash_parts,
+};
+
+static struct resource firebee_flash_resource = {
+	.start		= FLASH_PHYS_ADDR,
+	.end		= FLASH_PHYS_ADDR + FLASH_PHYS_SIZE,
+	.flags		= IORESOURCE_MEM,
+};
+
+static struct platform_device firebee_flash = {
+	.name		= "physmap-flash",
+	.id		= 0,
+	.dev		= {
+		.platform_data = &firebee_flash_data,
+	},
+	.num_resources	= 1,
+	.resource	= &firebee_flash_resource,
+};
+
+/***************************************************************************/
+
+static int __init init_firebee(void)
+{
+	platform_device_register(&firebee_flash);
+	return 0;
+}
+
+arch_initcall(init_firebee);
+
+/***************************************************************************/