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, 79 insertions, 0 deletions

diff --git a/drivers/hid/hid-ezkey.c b/drivers/hid/hid-ezkey.c
new file mode 100644
index 000000000..0e28bc0b8
--- /dev/null
+++ b/drivers/hid/hid-ezkey.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some ezkey "special" devices
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define ez_map_rel(c)	hid_map_usage(hi, usage, bit, max, EV_REL, (c))
+#define ez_map_key(c)	hid_map_usage(hi, usage, bit, max, EV_KEY, (c))
+
+static int ez_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER)
+		return 0;
+
+	switch (usage->hid & HID_USAGE) {
+	case 0x230: ez_map_key(BTN_MOUSE);	break;
+	case 0x231: ez_map_rel(REL_WHEEL);	break;
+	/*
+	 * this keyboard has a scrollwheel implemented in
+	 * totally broken way. We map this usage temporarily
+	 * to HWHEEL and handle it in the event quirk handler
+	 */
+	case 0x232: ez_map_rel(REL_HWHEEL);	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static int ez_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type)
+		return 0;
+
+	/* handle the temporary quirky mapping to HWHEEL */
+	if (usage->type == EV_REL && usage->code == REL_HWHEEL) {
+		struct input_dev *input = field->hidinput->input;
+		input_event(input, usage->type, REL_WHEEL, -value);
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id ez_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_EZKEY, USB_DEVICE_ID_BTC_8193) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, ez_devices);
+
+static struct hid_driver ez_driver = {
+	.name = "ezkey",
+	.id_table = ez_devices,
+	.input_mapping = ez_input_mapping,
+	.event = ez_event,
+};
+module_hid_driver(ez_driver);
+
+MODULE_DESCRIPTION("HID driver for some ezkey \"special\" devices");
+MODULE_LICENSE("GPL");