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, 88 insertions, 0 deletions

diff --git a/arch/powerpc/boot/ebony.c b/arch/powerpc/boot/ebony.c
new file mode 100644
index 000000000..add2316d3
--- /dev/null
+++ b/arch/powerpc/boot/ebony.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2007 David Gibson, IBM Corporation.
+ *
+ * Based on earlier code:
+ *   Copyright (C) Paul Mackerras 1997.
+ *
+ *   Matt Porter <mporter@kernel.crashing.org>
+ *   Copyright 2002-2005 MontaVista Software Inc.
+ *
+ *   Eugene Surovegin <eugene.surovegin@zultys.com> or <ebs@ebshome.net>
+ *   Copyright (c) 2003, 2004 Zultys Technologies
+ */
+#include <stdarg.h>
+#include <stddef.h>
+#include "types.h"
+#include "elf.h"
+#include "string.h"
+#include "stdio.h"
+#include "page.h"
+#include "ops.h"
+#include "reg.h"
+#include "io.h"
+#include "dcr.h"
+#include "4xx.h"
+#include "44x.h"
+
+static u8 *ebony_mac0, *ebony_mac1;
+
+#define EBONY_FPGA_PATH		"/plb/opb/ebc/fpga"
+#define	EBONY_FPGA_FLASH_SEL	0x01
+#define EBONY_SMALL_FLASH_PATH	"/plb/opb/ebc/small-flash"
+
+static void ebony_flashsel_fixup(void)
+{
+	void *devp;
+	u32 reg[3] = {0x0, 0x0, 0x80000};
+	u8 *fpga;
+	u8 fpga_reg0 = 0x0;
+
+	devp = finddevice(EBONY_FPGA_PATH);
+	if (!devp)
+		fatal("Couldn't locate FPGA node %s\n\r", EBONY_FPGA_PATH);
+
+	if (getprop(devp, "virtual-reg", &fpga, sizeof(fpga)) != sizeof(fpga))
+		fatal("%s has missing or invalid virtual-reg property\n\r",
+		      EBONY_FPGA_PATH);
+
+	fpga_reg0 = in_8(fpga);
+
+	devp = finddevice(EBONY_SMALL_FLASH_PATH);
+	if (!devp)
+		fatal("Couldn't locate small flash node %s\n\r",
+		      EBONY_SMALL_FLASH_PATH);
+
+	if (getprop(devp, "reg", reg, sizeof(reg)) != sizeof(reg))
+		fatal("%s has reg property of unexpected size\n\r",
+		      EBONY_SMALL_FLASH_PATH);
+
+	/* Invert address bit 14 (IBM-endian) if FLASH_SEL fpga bit is set */
+	if (fpga_reg0 & EBONY_FPGA_FLASH_SEL)
+		reg[1] ^= 0x80000;
+
+	setprop(devp, "reg", reg, sizeof(reg));
+}
+
+static void ebony_fixups(void)
+{
+	// FIXME: sysclk should be derived by reading the FPGA registers
+	unsigned long sysclk = 33000000;
+
+	ibm440gp_fixup_clocks(sysclk, 6 * 1843200);
+	ibm4xx_sdram_fixup_memsize();
+	dt_fixup_mac_address_by_alias("ethernet0", ebony_mac0);
+	dt_fixup_mac_address_by_alias("ethernet1", ebony_mac1);
+	ibm4xx_fixup_ebc_ranges("/plb/opb/ebc");
+	ebony_flashsel_fixup();
+}
+
+void ebony_init(void *mac0, void *mac1)
+{
+	platform_ops.fixups = ebony_fixups;
+	platform_ops.exit = ibm44x_dbcr_reset;
+	ebony_mac0 = mac0;
+	ebony_mac1 = mac1;
+	fdt_init(_dtb_start);
+	serial_console_init();
+}