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, 50 insertions, 0 deletions

diff --git a/drivers/hid/hid-penmount.c b/drivers/hid/hid-penmount.c
new file mode 100644
index 000000000..b9edc8e75
--- /dev/null
+++ b/drivers/hid/hid-penmount.c
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for PenMount touchscreens
+ *
+ *  Copyright (c) 2014 Christian Gmeiner <christian.gmeiner <at> gmail.com>
+ *
+ *  based on hid-penmount copyrighted by
+ *    PenMount Touch Solutions <penmount <at> seed.net.tw>
+ */
+
+/*
+ */
+
+#include <linux/module.h>
+#include <linux/hid.h>
+#include "hid-ids.h"
+
+static int penmount_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_BUTTON) {
+		if (((usage->hid - 1) & HID_USAGE) == 0) {
+			hid_map_usage(hi, usage, bit, max, EV_KEY, BTN_TOUCH);
+			return 1;
+		} else {
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id penmount_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_PENMOUNT, USB_DEVICE_ID_PENMOUNT_6000) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, penmount_devices);
+
+static struct hid_driver penmount_driver = {
+	.name = "hid-penmount",
+	.id_table = penmount_devices,
+	.input_mapping = penmount_input_mapping,
+};
+
+module_hid_driver(penmount_driver);
+
+MODULE_AUTHOR("Christian Gmeiner <christian.gmeiner@gmail.com>");
+MODULE_DESCRIPTION("PenMount HID TouchScreen driver");
+MODULE_LICENSE("GPL");