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, 155 insertions, 0 deletions

diff --git a/drivers/mfd/lp3943.c b/drivers/mfd/lp3943.c
new file mode 100644
index 000000000..1918b5c7a
--- /dev/null
+++ b/drivers/mfd/lp3943.c
@@ -0,0 +1,155 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TI/National Semiconductor LP3943 MFD Core Driver
+ *
+ * Copyright 2013 Texas Instruments
+ *
+ * Author: Milo Kim <milo.kim@ti.com>
+ *
+ * Driver structure:
+ *   LP3943 is an integrated device capable of driving 16 output channels.
+ *   It can be used for a GPIO expander and PWM generators.
+ *
+ *                                   LED control    General usage for a device
+ *                                   ___________   ____________________________
+ *
+ *   LP3943 MFD ---- GPIO expander    leds-gpio        eg) HW enable pin
+ *               |
+ *               --- PWM generator    leds-pwm         eg) PWM input
+ *
+ *   Internal two PWM channels are used for LED dimming effect.
+ *   And each output pin can be used as a GPIO as well.
+ *   The LED functionality can work with GPIOs or PWMs.
+ *   LEDs can be controlled with legacy leds-gpio(static brightness) or
+ *   leds-pwm drivers(dynamic brightness control).
+ *   Alternatively, it can be used for generic GPIO and PWM controller.
+ *   For example, a GPIO is HW enable pin of a device.
+ *   A PWM is input pin of a backlight device.
+ */
+
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/lp3943.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+#define LP3943_MAX_REGISTERS		0x09
+
+/* Register configuration for pin MUX */
+static const struct lp3943_reg_cfg lp3943_mux_cfg[] = {
+	/* address, mask, shift */
+	{ LP3943_REG_MUX0, 0x03, 0 },
+	{ LP3943_REG_MUX0, 0x0C, 2 },
+	{ LP3943_REG_MUX0, 0x30, 4 },
+	{ LP3943_REG_MUX0, 0xC0, 6 },
+	{ LP3943_REG_MUX1, 0x03, 0 },
+	{ LP3943_REG_MUX1, 0x0C, 2 },
+	{ LP3943_REG_MUX1, 0x30, 4 },
+	{ LP3943_REG_MUX1, 0xC0, 6 },
+	{ LP3943_REG_MUX2, 0x03, 0 },
+	{ LP3943_REG_MUX2, 0x0C, 2 },
+	{ LP3943_REG_MUX2, 0x30, 4 },
+	{ LP3943_REG_MUX2, 0xC0, 6 },
+	{ LP3943_REG_MUX3, 0x03, 0 },
+	{ LP3943_REG_MUX3, 0x0C, 2 },
+	{ LP3943_REG_MUX3, 0x30, 4 },
+	{ LP3943_REG_MUX3, 0xC0, 6 },
+};
+
+static const struct mfd_cell lp3943_devs[] = {
+	{
+		.name = "lp3943-pwm",
+		.of_compatible = "ti,lp3943-pwm",
+	},
+	{
+		.name = "lp3943-gpio",
+		.of_compatible = "ti,lp3943-gpio",
+	},
+};
+
+int lp3943_read_byte(struct lp3943 *lp3943, u8 reg, u8 *read)
+{
+	int ret;
+	unsigned int val;
+
+	ret = regmap_read(lp3943->regmap, reg, &val);
+	if (ret < 0)
+		return ret;
+
+	*read = (u8)val;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lp3943_read_byte);
+
+int lp3943_write_byte(struct lp3943 *lp3943, u8 reg, u8 data)
+{
+	return regmap_write(lp3943->regmap, reg, data);
+}
+EXPORT_SYMBOL_GPL(lp3943_write_byte);
+
+int lp3943_update_bits(struct lp3943 *lp3943, u8 reg, u8 mask, u8 data)
+{
+	return regmap_update_bits(lp3943->regmap, reg, mask, data);
+}
+EXPORT_SYMBOL_GPL(lp3943_update_bits);
+
+static const struct regmap_config lp3943_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LP3943_MAX_REGISTERS,
+};
+
+static int lp3943_probe(struct i2c_client *cl)
+{
+	struct lp3943 *lp3943;
+	struct device *dev = &cl->dev;
+
+	lp3943 = devm_kzalloc(dev, sizeof(*lp3943), GFP_KERNEL);
+	if (!lp3943)
+		return -ENOMEM;
+
+	lp3943->regmap = devm_regmap_init_i2c(cl, &lp3943_regmap_config);
+	if (IS_ERR(lp3943->regmap))
+		return PTR_ERR(lp3943->regmap);
+
+	lp3943->pdata = dev_get_platdata(dev);
+	lp3943->dev = dev;
+	lp3943->mux_cfg = lp3943_mux_cfg;
+	i2c_set_clientdata(cl, lp3943);
+
+	return devm_mfd_add_devices(dev, -1, lp3943_devs,
+				    ARRAY_SIZE(lp3943_devs),
+				    NULL, 0, NULL);
+}
+
+static const struct i2c_device_id lp3943_ids[] = {
+	{ "lp3943" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp3943_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id lp3943_of_match[] = {
+	{ .compatible = "ti,lp3943", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, lp3943_of_match);
+#endif
+
+static struct i2c_driver lp3943_driver = {
+	.probe = lp3943_probe,
+	.driver = {
+		.name = "lp3943",
+		.of_match_table = of_match_ptr(lp3943_of_match),
+	},
+	.id_table = lp3943_ids,
+};
+
+module_i2c_driver(lp3943_driver);
+
+MODULE_DESCRIPTION("LP3943 MFD Core Driver");
+MODULE_AUTHOR("Milo Kim");
+MODULE_LICENSE("GPL");