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, 83 insertions, 0 deletions

diff --git a/drivers/hid/hid-huawei.c b/drivers/hid/hid-huawei.c
new file mode 100644
index 000000000..ee3fc6f68
--- /dev/null
+++ b/drivers/hid/hid-huawei.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  HID driver for some huawei "special" devices
+ *
+ * Copyright (c) 2026 Miao Li <limiao@kylinos.cn>
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+
+static const __u8 huawei_cd30_kbd_rdesc_fixed[] = {
+	0x05, 0x01,		/* Usage Page (Generic Desktop)		*/
+	0x09, 0x80,		/* Usage (System Control)		*/
+	0xa1, 0x01,		/* Collection (Application)		*/
+	0x85, 0x01,		/*   Report ID (1)			*/
+	0x19, 0x81,		/*   Usage Minimum (System Power Down)	*/
+	0x29, 0x83,		/*   Usage Maximum (System Wake Up)	*/
+	0x15, 0x00,		/*   Logical Minimum (0)		*/
+	0x25, 0x01,		/*   Logical Maximum (1)		*/
+	0x75, 0x01,		/*   Report Size (1 bit)		*/
+	0x95, 0x03,		/*   Report Count (3)			*/
+	0x81, 0x02,		/*   Input (Data,Var,Abs)		*/
+	0x95, 0x05,		/*   Report Count (5)			*/
+	0x81, 0x01,		/*   Input (Cnst,Ary,Abs)		*/
+	0xc0,			/* End Collection			*/
+	0x05, 0x0c,		/* Usage Page (Consumer)		*/
+	0x09, 0x01,		/* Usage (Consumer Control)		*/
+	0xa1, 0x01,		/* Collection (Application)		*/
+	0x85, 0x02,		/*   Report ID (2)			*/
+	0x19, 0x00,		/*   Usage Minimum (0)			*/
+	0x2a, 0x3c, 0x02,	/*   Usage Maximum (0x023C)		*/
+	0x15, 0x00,		/*   Logical Minimum (0)		*/
+	0x26, 0x3c, 0x02,	/*   Logical Maximum (0x023C)		*/
+	0x95, 0x01,		/*   Report Count (1)			*/
+	0x75, 0x10,		/*   Report Size (16 bits)		*/
+	0x81, 0x00,		/*   Input (Data,Ary,Abs)		*/
+	0xc0			/* End Collection			*/
+};
+
+static const __u8 *huawei_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				  unsigned int *rsize)
+{
+	struct usb_interface *intf = hid_is_usb(hdev) ?
+			to_usb_interface(hdev->dev.parent) : NULL;
+
+	switch (hdev->product) {
+	case USB_DEVICE_ID_HUAWEI_CD30KBD:
+		if (!intf || intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+			if (*rsize != sizeof(huawei_cd30_kbd_rdesc_fixed) ||
+				memcmp(huawei_cd30_kbd_rdesc_fixed, rdesc,
+					sizeof(huawei_cd30_kbd_rdesc_fixed)) != 0) {
+				hid_info(hdev, "Replacing Huawei cd30 keyboard report descriptor.\n");
+				*rsize = sizeof(huawei_cd30_kbd_rdesc_fixed);
+				return huawei_cd30_kbd_rdesc_fixed;
+			}
+		}
+		break;
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id huawei_devices[] = {
+	/* HUAWEI cd30 keyboard */
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HUAWEI, USB_DEVICE_ID_HUAWEI_CD30KBD)},
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, huawei_devices);
+
+static struct hid_driver huawei_driver = {
+	.name = "huawei",
+	.id_table = huawei_devices,
+	.report_fixup = huawei_report_fixup,
+};
+module_hid_driver(huawei_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Miao Li <limiao@kylinos.cn>");
+MODULE_DESCRIPTION("HID driver for some huawei \"special\" devices");