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, 134 insertions, 0 deletions

diff --git a/drivers/input/misc/pcspkr.c b/drivers/input/misc/pcspkr.c
new file mode 100644
index 000000000..046780840
--- /dev/null
+++ b/drivers/input/misc/pcspkr.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  PC Speaker beeper driver for Linux
+ *
+ *  Copyright (c) 2002 Vojtech Pavlik
+ *  Copyright (c) 1992 Orest Zborowski
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i8253.h>
+#include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/timex.h>
+#include <linux/io.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("PC Speaker beeper driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pcspkr");
+
+static int pcspkr_event(struct input_dev *dev, unsigned int type,
+			unsigned int code, int value)
+{
+	unsigned int count = 0;
+	unsigned long flags;
+
+	if (type != EV_SND)
+		return -EINVAL;
+
+	switch (code) {
+	case SND_BELL:
+		if (value)
+			value = 1000;
+		break;
+	case SND_TONE:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (value > 20 && value < 32767)
+		count = PIT_TICK_RATE / value;
+
+	raw_spin_lock_irqsave(&i8253_lock, flags);
+
+	if (count) {
+		/* set command for counter 2, 2 byte write */
+		outb_p(0xB6, 0x43);
+		/* select desired HZ */
+		outb_p(count & 0xff, 0x42);
+		outb((count >> 8) & 0xff, 0x42);
+		/* enable counter 2 */
+		outb_p(inb_p(0x61) | 3, 0x61);
+	} else {
+		/* disable counter 2 */
+		outb(inb_p(0x61) & 0xFC, 0x61);
+	}
+
+	raw_spin_unlock_irqrestore(&i8253_lock, flags);
+
+	return 0;
+}
+
+static int pcspkr_probe(struct platform_device *dev)
+{
+	struct input_dev *pcspkr_dev;
+	int err;
+
+	pcspkr_dev = input_allocate_device();
+	if (!pcspkr_dev)
+		return -ENOMEM;
+
+	pcspkr_dev->name = "PC Speaker";
+	pcspkr_dev->phys = "isa0061/input0";
+	pcspkr_dev->id.bustype = BUS_ISA;
+	pcspkr_dev->id.vendor = 0x001f;
+	pcspkr_dev->id.product = 0x0001;
+	pcspkr_dev->id.version = 0x0100;
+	pcspkr_dev->dev.parent = &dev->dev;
+
+	pcspkr_dev->evbit[0] = BIT_MASK(EV_SND);
+	pcspkr_dev->sndbit[0] = BIT_MASK(SND_BELL) | BIT_MASK(SND_TONE);
+	pcspkr_dev->event = pcspkr_event;
+
+	err = input_register_device(pcspkr_dev);
+	if (err) {
+		input_free_device(pcspkr_dev);
+		return err;
+	}
+
+	platform_set_drvdata(dev, pcspkr_dev);
+
+	return 0;
+}
+
+static void pcspkr_remove(struct platform_device *dev)
+{
+	struct input_dev *pcspkr_dev = platform_get_drvdata(dev);
+
+	input_unregister_device(pcspkr_dev);
+	/* turn off the speaker */
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+}
+
+static int pcspkr_suspend(struct device *dev)
+{
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+
+	return 0;
+}
+
+static void pcspkr_shutdown(struct platform_device *dev)
+{
+	/* turn off the speaker */
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+}
+
+static const struct dev_pm_ops pcspkr_pm_ops = {
+	.suspend = pcspkr_suspend,
+};
+
+static struct platform_driver pcspkr_platform_driver = {
+	.driver		= {
+		.name	= "pcspkr",
+		.pm	= &pcspkr_pm_ops,
+	},
+	.probe		= pcspkr_probe,
+	.remove		= pcspkr_remove,
+	.shutdown	= pcspkr_shutdown,
+};
+module_platform_driver(pcspkr_platform_driver);
+