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, 159 insertions, 0 deletions

diff --git a/drivers/hid/hid-sjoy.c b/drivers/hid/hid-sjoy.c
new file mode 100644
index 000000000..193ab2a61
--- /dev/null
+++ b/drivers/hid/hid-sjoy.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Force feedback support for SmartJoy PLUS PS2->USB adapter
+ *
+ *  Copyright (c) 2009 Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
+ *
+ *  Based of hid-pl.c and hid-gaff.c
+ *   Copyright (c) 2007, 2009 Anssi Hannula <anssi.hannula@gmail.com>
+ *   Copyright (c) 2008 Lukasz Lubojanski <lukasz@lubojanski.info>
+ */
+
+/*
+ */
+
+/* #define DEBUG */
+
+#include <linux/input.h>
+#include <linux/slab.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+#ifdef CONFIG_SMARTJOYPLUS_FF
+
+struct sjoyff_device {
+	struct hid_report *report;
+};
+
+static int hid_sjoyff_play(struct input_dev *dev, void *data,
+			 struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct sjoyff_device *sjoyff = data;
+	u32 left, right;
+
+	left = effect->u.rumble.strong_magnitude;
+	right = effect->u.rumble.weak_magnitude;
+	dev_dbg(&dev->dev, "called with 0x%08x 0x%08x\n", left, right);
+
+	left = left * 0xff / 0xffff;
+	right = (right != 0); /* on/off only */
+
+	sjoyff->report->field[0]->value[1] = right;
+	sjoyff->report->field[0]->value[2] = left;
+	dev_dbg(&dev->dev, "running with 0x%02x 0x%02x\n", left, right);
+	hid_hw_request(hid, sjoyff->report, HID_REQ_SET_REPORT);
+
+	return 0;
+}
+
+static int sjoy_input_configured(struct hid_device *hid, struct hid_input *hidinput)
+{
+	struct sjoyff_device *sjoyff;
+	struct hid_report *report;
+	struct list_head *report_list =
+			&hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	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) {
+		hid_err(hid, "no fields in the report\n");
+		return -ENODEV;
+	}
+
+	if (report->field[0]->report_count < 3) {
+		hid_err(hid, "not enough values in the field\n");
+		return -ENODEV;
+	}
+
+	sjoyff = kzalloc_obj(struct sjoyff_device);
+	if (!sjoyff)
+		return -ENOMEM;
+
+	set_bit(FF_RUMBLE, dev->ffbit);
+
+	sjoyff->report = report;
+	sjoyff->report->field[0]->value[0] = 0x01;
+	sjoyff->report->field[0]->value[1] = 0x00;
+	sjoyff->report->field[0]->value[2] = 0x00;
+	hid_hw_request(hid, sjoyff->report, HID_REQ_SET_REPORT);
+
+	error = input_ff_create_memless(dev, sjoyff, hid_sjoyff_play);
+	if (error) {
+		kfree(sjoyff);
+		return error;
+	}
+
+	return 0;
+}
+#else
+static inline int sjoy_input_configured(struct hid_device *hid,
+					struct hid_input *hidinput)
+{
+	return 0;
+}
+#endif
+
+static int sjoy_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	int ret;
+
+	hdev->quirks |= id->driver_data;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id sjoy_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP_LTD, USB_DEVICE_ID_SUPER_JOY_BOX_3_PRO),
+		.driver_data = HID_QUIRK_NOGET },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP_LTD, USB_DEVICE_ID_SUPER_DUAL_BOX_PRO),
+		.driver_data = HID_QUIRK_MULTI_INPUT | HID_QUIRK_NOGET |
+			       HID_QUIRK_SKIP_OUTPUT_REPORTS },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP_LTD, USB_DEVICE_ID_SUPER_JOY_BOX_5_PRO),
+		.driver_data = HID_QUIRK_MULTI_INPUT | HID_QUIRK_NOGET |
+			       HID_QUIRK_SKIP_OUTPUT_REPORTS },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP, USB_DEVICE_ID_SMARTJOY_PLUS) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP, USB_DEVICE_ID_SUPER_JOY_BOX_3) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_WISEGROUP, USB_DEVICE_ID_DUAL_USB_JOYPAD),
+		.driver_data = HID_QUIRK_MULTI_INPUT |
+			       HID_QUIRK_SKIP_OUTPUT_REPORTS },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_PLAYDOTCOM, USB_DEVICE_ID_PLAYDOTCOM_EMS_USBII),
+		.driver_data = HID_QUIRK_MULTI_INPUT |
+			       HID_QUIRK_SKIP_OUTPUT_REPORTS },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, sjoy_devices);
+
+static struct hid_driver sjoy_driver = {
+	.name = "smartjoyplus",
+	.id_table = sjoy_devices,
+	.probe = sjoy_probe,
+	.input_configured = sjoy_input_configured,
+};
+module_hid_driver(sjoy_driver);
+
+MODULE_DESCRIPTION("Force feedback support for SmartJoy PLUS PS2->USB adapter");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jussi Kivilinna");
+