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, 114 insertions, 0 deletions

diff --git a/drivers/hid/hid-holtek-mouse.c b/drivers/hid/hid-holtek-mouse.c
new file mode 100644
index 000000000..b618a1646
--- /dev/null
+++ b/drivers/hid/hid-holtek-mouse.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HID driver for Holtek gaming mice
+ * Copyright (c) 2013 Christian Ohm
+ * Heavily inspired by various other HID drivers that adjust the report
+ * descriptor.
+*/
+
+/*
+ */
+
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+/*
+ * The report descriptor of some Holtek based gaming mice specifies an
+ * excessively large number of consumer usages (2^15), which is more than
+ * HID_MAX_USAGES. This prevents proper parsing of the report descriptor.
+ *
+ * This driver fixes the report descriptor for:
+ * - USB ID 04d9:a067, sold as Sharkoon Drakonia and Perixx MX-2000
+ * - USB ID 04d9:a04a, sold as Tracer Sniper TRM-503, NOVA Gaming Slider X200
+ *   and Zalman ZM-GM1
+ * - USB ID 04d9:a081, sold as SHARKOON DarkGlider Gaming mouse
+ * - USB ID 04d9:a072, sold as LEETGION Hellion Gaming Mouse
+ * - USB ID 04d9:a0c2, sold as ETEKCITY Scroll T-140 Gaming Mouse
+ */
+
+static const __u8 *holtek_mouse_report_fixup(struct hid_device *hdev,
+		__u8 *rdesc, unsigned int *rsize)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		/* Change usage maximum and logical maximum from 0x7fff to
+		 * 0x2fff, so they don't exceed HID_MAX_USAGES */
+		switch (hdev->product) {
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A067:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A072:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A0C2:
+			if (*rsize >= 122 && rdesc[115] == 0xff && rdesc[116] == 0x7f
+					&& rdesc[120] == 0xff && rdesc[121] == 0x7f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[116] = rdesc[121] = 0x2f;
+			}
+			break;
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A04A:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A070:
+		case USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A081:
+			if (*rsize >= 113 && rdesc[106] == 0xff && rdesc[107] == 0x7f
+					&& rdesc[111] == 0xff && rdesc[112] == 0x7f) {
+				hid_info(hdev, "Fixing up report descriptor\n");
+				rdesc[107] = rdesc[112] = 0x2f;
+			}
+			break;
+		}
+
+	}
+	return rdesc;
+}
+
+static int holtek_mouse_probe(struct hid_device *hdev,
+			      const struct hid_device_id *id)
+{
+	int ret;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "hid parse failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id holtek_mouse_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A067) },
+        { HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A070) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A04A) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A072) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A081) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_MOUSE_A0C2) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, holtek_mouse_devices);
+
+static struct hid_driver holtek_mouse_driver = {
+	.name = "holtek_mouse",
+	.id_table = holtek_mouse_devices,
+	.report_fixup = holtek_mouse_report_fixup,
+	.probe = holtek_mouse_probe,
+};
+
+module_hid_driver(holtek_mouse_driver);
+MODULE_DESCRIPTION("HID driver for Holtek gaming mice");
+MODULE_LICENSE("GPL");