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, 147 insertions, 0 deletions

diff --git a/drivers/hid/hid-mf.c b/drivers/hid/hid-mf.c
new file mode 100644
index 000000000..136e8b41d
--- /dev/null
+++ b/drivers/hid/hid-mf.c
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Force feedback support for Mayflash game controller adapters.
+ *
+ * These devices are manufactured by Mayflash but identify themselves
+ * using the vendor ID of DragonRise Inc.
+ *
+ * Tested with:
+ * 0079:1801 "DragonRise Inc. Mayflash PS3 Game Controller Adapter"
+ * 0079:1803 "DragonRise Inc. Mayflash Wireless Sensor DolphinBar"
+ * 0079:1843 "DragonRise Inc. Mayflash GameCube Game Controller Adapter"
+ * 0079:1844 "DragonRise Inc. Mayflash GameCube Game Controller Adapter (v04)"
+ *
+ * The following adapters probably work too, but need to be tested:
+ * 0079:1800 "DragonRise Inc. Mayflash WIIU Game Controller Adapter"
+ *
+ * Copyright (c) 2016-2017 Marcel Hasler <mahasler@gmail.com>
+ */
+
+/*
+ */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+struct mf_device {
+	struct hid_report *report;
+};
+
+static int mf_play(struct input_dev *dev, void *data, struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct mf_device *mf = data;
+	int strong, weak;
+
+	strong = effect->u.rumble.strong_magnitude;
+	weak = effect->u.rumble.weak_magnitude;
+
+	dbg_hid("Called with 0x%04x 0x%04x.\n", strong, weak);
+
+	strong = strong * 0xff / 0xffff;
+	weak = weak * 0xff / 0xffff;
+
+	dbg_hid("Running with 0x%02x 0x%02x.\n", strong, weak);
+
+	mf->report->field[0]->value[0] = weak;
+	mf->report->field[0]->value[1] = strong;
+	hid_hw_request(hid, mf->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int mf_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	struct mf_device *mf;
+	struct list_head *report_list =
+			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report;
+	struct input_dev *dev = hidinput->input;
+	int error;
+
+	if (!list_is_first(&hidinput->list, &hid->inputs))
+		return 0;
+
+	report = list_first_entry_or_null(report_list, struct hid_report, list);
+	if (!report) {
+		hid_err(hid, "no output reports found\n");
+		return -ENODEV;
+	}
+
+	if (report->maxfield < 1 || report->field[0]->report_count < 2) {
+		hid_err(hid, "Invalid report, this should never happen!\n");
+		return -ENODEV;
+	}
+
+	mf = kzalloc_obj(struct mf_device);
+	if (!mf)
+		return -ENOMEM;
+
+	mf->report = report;
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	error = input_ff_create_memless(dev, mf, mf_play);
+	if (error) {
+		kfree(mf);
+		return error;
+	}
+
+	mf->report->field[0]->value[0] = 0x00;
+	mf->report->field[0]->value[1] = 0x00;
+	hid_hw_request(hid, mf->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int mf_probe(struct hid_device *hid, const struct hid_device_id *id)
+{
+	int error;
+
+	dev_dbg(&hid->dev, "Mayflash HID hardware probe...\n");
+
+	/* Apply quirks as needed */
+	hid->quirks |= id->driver_data;
+
+	error = hid_parse(hid);
+	if (error) {
+		hid_err(hid, "HID parse failed.\n");
+		return error;
+	}
+
+	error = hid_hw_start(hid, HID_CONNECT_DEFAULT);
+	if (error) {
+		hid_err(hid, "HID hw start failed\n");
+		return error;
+	}
+
+	return 0;
+}
+static const struct hid_device_id mf_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_PS3),
+		.driver_data = HID_QUIRK_MULTI_INPUT },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_DOLPHINBAR),
+		.driver_data = HID_QUIRK_MULTI_INPUT },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_GAMECUBE1),
+		.driver_data = HID_QUIRK_MULTI_INPUT },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_GAMECUBE2),
+		.driver_data = 0 }, /* No quirk required */
+	{ HID_USB_DEVICE(USB_VENDOR_ID_DRAGONRISE, USB_DEVICE_ID_DRAGONRISE_GAMECUBE3),
+		.driver_data = HID_QUIRK_MULTI_INPUT },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, mf_devices);
+
+static struct hid_driver mf_driver = {
+	.name = "hid_mf",
+	.id_table = mf_devices,
+	.probe = mf_probe,
+	.input_configured = mf_input_configured,
+};
+module_hid_driver(mf_driver);
+
+MODULE_DESCRIPTION("Force feedback support for Mayflash game controller adapters.");
+MODULE_LICENSE("GPL");