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/drivers/mfd/sky81452.c b/drivers/mfd/sky81452.c
new file mode 100644
index 000000000..771b62a5c
--- /dev/null
+++ b/drivers/mfd/sky81452.c
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sky81452.c	SKY81452 MFD driver
+ *
+ * Copyright 2014 Skyworks Solutions Inc.
+ * Author : Gyungoh Yoo <jack.yoo@skyworksinc.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/sky81452.h>
+
+static const struct regmap_config sky81452_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static int sky81452_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	const struct sky81452_platform_data *pdata = dev_get_platdata(dev);
+	struct mfd_cell cells[2];
+	struct regmap *regmap;
+	int ret;
+
+	if (!pdata) {
+		pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+		if (!pdata)
+			return -ENOMEM;
+	}
+
+	regmap = devm_regmap_init_i2c(client, &sky81452_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "failed to initialize.err=%ld\n", PTR_ERR(regmap));
+		return PTR_ERR(regmap);
+	}
+
+	i2c_set_clientdata(client, regmap);
+
+	memset(cells, 0, sizeof(cells));
+	cells[0].name = "sky81452-backlight";
+	cells[0].of_compatible = "skyworks,sky81452-backlight";
+	cells[1].name = "sky81452-regulator";
+	cells[1].platform_data = pdata->regulator_init_data;
+	cells[1].pdata_size = sizeof(*pdata->regulator_init_data);
+
+	ret = devm_mfd_add_devices(dev, -1, cells, ARRAY_SIZE(cells),
+				   NULL, 0, NULL);
+	if (ret)
+		dev_err(dev, "failed to add child devices. err=%d\n", ret);
+
+	return ret;
+}
+
+static const struct i2c_device_id sky81452_ids[] = {
+	{ "sky81452" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, sky81452_ids);
+
+#ifdef CONFIG_OF
+static const struct of_device_id sky81452_of_match[] = {
+	{ .compatible = "skyworks,sky81452", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sky81452_of_match);
+#endif
+
+static struct i2c_driver sky81452_driver = {
+	.driver = {
+		.name = "sky81452",
+		.of_match_table = of_match_ptr(sky81452_of_match),
+	},
+	.probe = sky81452_probe,
+	.id_table = sky81452_ids,
+};
+
+module_i2c_driver(sky81452_driver);
+
+MODULE_DESCRIPTION("Skyworks SKY81452 MFD driver");
+MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@skyworksinc.com>");
+MODULE_LICENSE("GPL v2");