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, 164 insertions, 0 deletions

diff --git a/arch/mips/n64/init.c b/arch/mips/n64/init.c
new file mode 100644
index 000000000..66ec28ab4
--- /dev/null
+++ b/arch/mips/n64/init.c
@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Nintendo 64 init.
+ *
+ *  Copyright (C) 2021	Lauri Kasanen
+ */
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/memblock.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/simplefb.h>
+#include <linux/string.h>
+
+#include <asm/bootinfo.h>
+#include <asm/fw/fw.h>
+#include <asm/time.h>
+
+#define IO_MEM_RESOURCE_START	0UL
+#define IO_MEM_RESOURCE_END	0x1fffffffUL
+
+/*
+ * System-specifc irq names for clarity
+ */
+#define MIPS_CPU_IRQ(x)		(MIPS_CPU_IRQ_BASE + (x))
+#define MIPS_SOFTINT0_IRQ	MIPS_CPU_IRQ(0)
+#define MIPS_SOFTINT1_IRQ	MIPS_CPU_IRQ(1)
+#define RCP_IRQ			MIPS_CPU_IRQ(2)
+#define CART_IRQ		MIPS_CPU_IRQ(3)
+#define PRENMI_IRQ		MIPS_CPU_IRQ(4)
+#define RDBR_IRQ		MIPS_CPU_IRQ(5)
+#define RDBW_IRQ		MIPS_CPU_IRQ(6)
+#define TIMER_IRQ		MIPS_CPU_IRQ(7)
+
+static void __init iomem_resource_init(void)
+{
+	iomem_resource.start = IO_MEM_RESOURCE_START;
+	iomem_resource.end = IO_MEM_RESOURCE_END;
+}
+
+const char *get_system_type(void)
+{
+	return "Nintendo 64";
+}
+
+void __init prom_init(void)
+{
+	fw_init_cmdline();
+}
+
+#define W 320
+#define H 240
+#define REG_BASE ((u32 __iomem *) CKSEG1ADDR(0x4400000))
+
+static void __init n64rdp_write_reg(const u8 reg, const u32 value)
+{
+	__raw_writel(value, REG_BASE + reg);
+}
+
+#undef REG_BASE
+
+static const u32 ntsc_320[] __initconst = {
+	0x00013212, 0x00000000, 0x00000140, 0x00000200,
+	0x00000000, 0x03e52239, 0x0000020d, 0x00000c15,
+	0x0c150c15, 0x006c02ec, 0x002501ff, 0x000e0204,
+	0x00000200, 0x00000400
+};
+
+#define MI_REG_BASE 0x4300000
+#define NUM_MI_REGS 4
+#define AI_REG_BASE 0x4500000
+#define NUM_AI_REGS 6
+#define PI_REG_BASE 0x4600000
+#define NUM_PI_REGS 5
+#define SI_REG_BASE 0x4800000
+#define NUM_SI_REGS 7
+
+static int __init n64_platform_init(void)
+{
+	static const char simplefb_resname[] = "FB";
+	static const struct simplefb_platform_data mode = {
+		.width = W,
+		.height = H,
+		.stride = W * 2,
+		.format = "r5g5b5a1"
+	};
+	struct resource res[3];
+	void *orig;
+	unsigned long phys;
+	unsigned i;
+
+	memset(res, 0, sizeof(struct resource) * 3);
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = MI_REG_BASE;
+	res[0].end = MI_REG_BASE + NUM_MI_REGS * 4 - 1;
+
+	res[1].flags = IORESOURCE_MEM;
+	res[1].start = AI_REG_BASE;
+	res[1].end = AI_REG_BASE + NUM_AI_REGS * 4 - 1;
+
+	res[2].flags = IORESOURCE_IRQ;
+	res[2].start = RCP_IRQ;
+	res[2].end = RCP_IRQ;
+
+	platform_device_register_simple("n64audio", -1, res, 3);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = PI_REG_BASE;
+	res[0].end = PI_REG_BASE + NUM_PI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64cart", -1, res, 1);
+
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].start = SI_REG_BASE;
+	res[0].end = SI_REG_BASE + NUM_SI_REGS * 4 - 1;
+
+	platform_device_register_simple("n64joy", -1, res, 1);
+
+	/* The framebuffer needs 64-byte alignment */
+	orig = kzalloc(W * H * 2 + 63, GFP_DMA | GFP_KERNEL);
+	if (!orig)
+		return -ENOMEM;
+	phys = virt_to_phys(orig);
+	phys += 63;
+	phys &= ~63;
+
+	for (i = 0; i < ARRAY_SIZE(ntsc_320); i++) {
+		if (i == 1)
+			n64rdp_write_reg(i, phys);
+		else
+			n64rdp_write_reg(i, ntsc_320[i]);
+	}
+
+	/* setup IORESOURCE_MEM as framebuffer memory */
+	memset(&res[0], 0, sizeof(res[0]));
+	res[0].flags = IORESOURCE_MEM;
+	res[0].name = simplefb_resname;
+	res[0].start = phys;
+	res[0].end = phys + W * H * 2 - 1;
+
+	platform_device_register_resndata(NULL, "simple-framebuffer", 0,
+					  &res[0], 1, &mode, sizeof(mode));
+
+	return 0;
+}
+
+#undef W
+#undef H
+
+arch_initcall(n64_platform_init);
+
+void __init plat_mem_setup(void)
+{
+	iomem_resource_init();
+	memblock_add(0x0, 8 * 1024 * 1024); /* Bootloader blocks the 4mb config */
+}
+
+void __init plat_time_init(void)
+{
+	/* 93.75 MHz cpu, count register runs at half rate */
+	mips_hpt_frequency = 93750000 / 2;
+}