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, 177 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-moxtet.c b/drivers/gpio/gpio-moxtet.c
new file mode 100644
index 000000000..4eb9f1a27
--- /dev/null
+++ b/drivers/gpio/gpio-moxtet.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  Turris Mox Moxtet GPIO expander
+ *
+ *  Copyright (C) 2018 Marek Behún <kabel@kernel.org>
+ */
+
+#include <linux/bitops.h>
+#include <linux/gpio/driver.h>
+#include <linux/moxtet.h>
+#include <linux/module.h>
+
+#define MOXTET_GPIO_NGPIOS	12
+#define MOXTET_GPIO_INPUTS	4
+
+struct moxtet_gpio_desc {
+	u16 in_mask;
+	u16 out_mask;
+};
+
+static const struct moxtet_gpio_desc descs[] = {
+	[TURRIS_MOX_MODULE_SFP] = {
+		.in_mask = GENMASK(2, 0),
+		.out_mask = GENMASK(5, 4),
+	},
+};
+
+struct moxtet_gpio_chip {
+	struct device			*dev;
+	struct gpio_chip		gpio_chip;
+	const struct moxtet_gpio_desc	*desc;
+};
+
+static int moxtet_gpio_get_value(struct gpio_chip *gc, unsigned int offset)
+{
+	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+	int ret;
+
+	if (chip->desc->in_mask & BIT(offset)) {
+		ret = moxtet_device_read(chip->dev);
+	} else if (chip->desc->out_mask & BIT(offset)) {
+		ret = moxtet_device_written(chip->dev);
+		if (ret >= 0)
+			ret <<= MOXTET_GPIO_INPUTS;
+	} else {
+		return -EINVAL;
+	}
+
+	if (ret < 0)
+		return ret;
+
+	return !!(ret & BIT(offset));
+}
+
+static int moxtet_gpio_set_value(struct gpio_chip *gc, unsigned int offset,
+				 int val)
+{
+	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+	int state;
+
+	state = moxtet_device_written(chip->dev);
+	if (state < 0)
+		return state;
+
+	offset -= MOXTET_GPIO_INPUTS;
+
+	if (val)
+		state |= BIT(offset);
+	else
+		state &= ~BIT(offset);
+
+	return moxtet_device_write(chip->dev, state);
+}
+
+static int moxtet_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+	/* All lines are hard wired to be either input or output, not both. */
+	if (chip->desc->in_mask & BIT(offset))
+		return GPIO_LINE_DIRECTION_IN;
+	else if (chip->desc->out_mask & BIT(offset))
+		return GPIO_LINE_DIRECTION_OUT;
+	else
+		return -EINVAL;
+}
+
+static int moxtet_gpio_direction_input(struct gpio_chip *gc,
+				       unsigned int offset)
+{
+	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+	if (chip->desc->in_mask & BIT(offset))
+		return 0;
+	else if (chip->desc->out_mask & BIT(offset))
+		return -ENOTSUPP;
+	else
+		return -EINVAL;
+}
+
+static int moxtet_gpio_direction_output(struct gpio_chip *gc,
+					unsigned int offset, int val)
+{
+	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);
+
+	if (chip->desc->out_mask & BIT(offset))
+		return moxtet_gpio_set_value(gc, offset, val);
+	else if (chip->desc->in_mask & BIT(offset))
+		return -ENOTSUPP;
+
+	return -EINVAL;
+}
+
+static int moxtet_gpio_probe(struct device *dev)
+{
+	struct moxtet_gpio_chip *chip;
+	struct device_node *nc = dev->of_node;
+	int id;
+
+	id = to_moxtet_device(dev)->id;
+
+	if (id >= ARRAY_SIZE(descs)) {
+		dev_err(dev, "%pOF Moxtet device id 0x%x is not supported by gpio-moxtet driver\n",
+			nc, id);
+		return -ENOTSUPP;
+	}
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->dev = dev;
+	chip->gpio_chip.parent = dev;
+	chip->desc = &descs[id];
+
+	dev_set_drvdata(dev, chip);
+
+	chip->gpio_chip.label = dev_name(dev);
+	chip->gpio_chip.get_direction = moxtet_gpio_get_direction;
+	chip->gpio_chip.direction_input = moxtet_gpio_direction_input;
+	chip->gpio_chip.direction_output = moxtet_gpio_direction_output;
+	chip->gpio_chip.get = moxtet_gpio_get_value;
+	chip->gpio_chip.set = moxtet_gpio_set_value;
+	chip->gpio_chip.base = -1;
+
+	chip->gpio_chip.ngpio = MOXTET_GPIO_NGPIOS;
+
+	chip->gpio_chip.can_sleep = true;
+	chip->gpio_chip.owner = THIS_MODULE;
+
+	return devm_gpiochip_add_data(dev, &chip->gpio_chip, chip);
+}
+
+static const struct of_device_id moxtet_gpio_dt_ids[] = {
+	{ .compatible = "cznic,moxtet-gpio", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, moxtet_gpio_dt_ids);
+
+static const enum turris_mox_module_id moxtet_gpio_module_table[] = {
+	TURRIS_MOX_MODULE_SFP,
+	0,
+};
+
+static struct moxtet_driver moxtet_gpio_driver = {
+	.driver = {
+		.name		= "moxtet-gpio",
+		.of_match_table	= moxtet_gpio_dt_ids,
+		.probe		= moxtet_gpio_probe,
+	},
+	.id_table = moxtet_gpio_module_table,
+};
+module_moxtet_driver(moxtet_gpio_driver);
+
+MODULE_AUTHOR("Marek Behun <kabel@kernel.org>");
+MODULE_DESCRIPTION("Turris Mox Moxtet GPIO expander");
+MODULE_LICENSE("GPL v2");