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, 217 insertions, 0 deletions

diff --git a/drivers/media/rc/ir-xmp-decoder.c b/drivers/media/rc/ir-xmp-decoder.c
new file mode 100644
index 000000000..dc36b6873
--- /dev/null
+++ b/drivers/media/rc/ir-xmp-decoder.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
+ *
+ * Copyright (C) 2014 by Marcel Mol
+ *
+ * - Based on info from http://www.hifi-remote.com
+ * - Ignore Toggle=9 frames
+ * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
+ */
+
+#include <linux/bitrev.h>
+#include <linux/module.h>
+#include "rc-core-priv.h"
+
+#define XMP_UNIT		  136 /* us */
+#define XMP_LEADER		  210 /* us */
+#define XMP_NIBBLE_PREFIX	  760 /* us */
+#define	XMP_HALFFRAME_SPACE	13800 /* us */
+/* should be 80ms but not all duration supliers can go that high */
+#define	XMP_TRAILER_SPACE	20000
+
+enum xmp_state {
+	STATE_INACTIVE,
+	STATE_LEADER_PULSE,
+	STATE_NIBBLE_SPACE,
+};
+
+/**
+ * ir_xmp_decode() - Decode one XMP pulse or space
+ * @dev:	the struct rc_dev descriptor of the device
+ * @ev:		the struct ir_raw_event descriptor of the pulse/space
+ *
+ * This function returns -EINVAL if the pulse violates the state machine
+ */
+static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
+{
+	struct xmp_dec *data = &dev->raw->xmp;
+
+	if (!is_timing_event(ev)) {
+		if (ev.overflow)
+			data->state = STATE_INACTIVE;
+		return 0;
+	}
+
+	dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
+		data->state, data->count, ev.duration, TO_STR(ev.pulse));
+
+	switch (data->state) {
+
+	case STATE_INACTIVE:
+		if (!ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
+			data->count = 0;
+			data->state = STATE_NIBBLE_SPACE;
+		}
+
+		return 0;
+
+	case STATE_LEADER_PULSE:
+		if (!ev.pulse)
+			break;
+
+		if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
+			data->state = STATE_NIBBLE_SPACE;
+
+		return 0;
+
+	case STATE_NIBBLE_SPACE:
+		if (ev.pulse)
+			break;
+
+		if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
+			int divider, i;
+			u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
+			u32 *n;
+			u32 scancode;
+
+			if (data->count != 16) {
+				dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
+					data->count, ev.duration);
+				data->state = STATE_INACTIVE;
+				return -EINVAL;
+			}
+
+			n = data->durations;
+			/*
+			 * the 4th nibble should be 15 so base the divider on this
+			 * to transform durations into nibbles. Subtract 2000 from
+			 * the divider to compensate for fluctuations in the signal
+			 */
+			divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
+			if (divider < 50) {
+				dev_dbg(&dev->dev, "divider to small %d.\n",
+					divider);
+				data->state = STATE_INACTIVE;
+				return -EINVAL;
+			}
+
+			/* convert to nibbles and do some sanity checks */
+			for (i = 0; i < 16; i++)
+				n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
+			sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
+				n[4] + n[5] + n[6] + n[7]) % 16;
+			sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
+				n[12] + n[13] + n[14] + n[15]) % 16;
+
+			if (sum1 != 15 || sum2 != 15) {
+				dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
+					sum1, sum2);
+				data->state = STATE_INACTIVE;
+				return -EINVAL;
+			}
+
+			subaddr  = n[0] << 4 | n[2];
+			subaddr2 = n[8] << 4 | n[11];
+			oem      = n[4] << 4 | n[5];
+			addr     = n[6] << 4 | n[7];
+			toggle   = n[10];
+			obc1 = n[12] << 4 | n[13];
+			obc2 = n[14] << 4 | n[15];
+			if (subaddr != subaddr2) {
+				dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
+					subaddr, subaddr2);
+				data->state = STATE_INACTIVE;
+				return -EINVAL;
+			}
+			if (oem != 0x44)
+				dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
+					oem);
+
+			scancode = addr << 24 | subaddr << 16 |
+				   obc1 << 8 | obc2;
+			dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
+
+			if (toggle == 0) {
+				rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
+			} else {
+				rc_repeat(dev);
+				dev_dbg(&dev->dev, "Repeat last key\n");
+			}
+			data->state = STATE_INACTIVE;
+
+			return 0;
+
+		} else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
+			/* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
+			if (data->count == 16) {
+				dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
+					data->count, ev.duration);
+				/*
+				 * TODO: for now go back to half frame position
+				 *	 so trailer can be found and key press
+				 *	 can be handled.
+				 */
+				data->count = 8;
+			}
+
+			else if (data->count != 8)
+				dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
+					data->count, ev.duration);
+			data->state = STATE_LEADER_PULSE;
+
+			return 0;
+
+		} else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
+			/* store nibble raw data, decode after trailer */
+			if (data->count == 16) {
+				dev_dbg(&dev->dev, "too many pulses (%d) ignoring: %u\n",
+					data->count, ev.duration);
+				data->state = STATE_INACTIVE;
+				return -EINVAL;
+			}
+			data->durations[data->count] = ev.duration;
+			data->count++;
+			data->state = STATE_LEADER_PULSE;
+
+			return 0;
+
+		}
+
+		break;
+	}
+
+	dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
+		data->count, data->state, ev.duration, TO_STR(ev.pulse));
+	data->state = STATE_INACTIVE;
+	return -EINVAL;
+}
+
+static struct ir_raw_handler xmp_handler = {
+	.protocols	= RC_PROTO_BIT_XMP,
+	.decode		= ir_xmp_decode,
+	.min_timeout	= XMP_TRAILER_SPACE,
+};
+
+static int __init ir_xmp_decode_init(void)
+{
+	ir_raw_handler_register(&xmp_handler);
+
+	printk(KERN_INFO "IR XMP protocol handler initialized\n");
+	return 0;
+}
+
+static void __exit ir_xmp_decode_exit(void)
+{
+	ir_raw_handler_unregister(&xmp_handler);
+}
+
+module_init(ir_xmp_decode_init);
+module_exit(ir_xmp_decode_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
+MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
+MODULE_DESCRIPTION("XMP IR protocol decoder");