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, 331 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/ec100.c b/drivers/media/dvb-frontends/ec100.c
new file mode 100644
index 000000000..b7a3572f8
--- /dev/null
+++ b/drivers/media/dvb-frontends/ec100.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * E3C EC100 demodulator driver
+ *
+ * Copyright (C) 2009 Antti Palosaari <crope@iki.fi>
+ */
+
+#include <media/dvb_frontend.h>
+#include "ec100.h"
+
+struct ec100_state {
+	struct i2c_adapter *i2c;
+	struct dvb_frontend frontend;
+	struct ec100_config config;
+
+	u16 ber;
+};
+
+/* write single register */
+static int ec100_write_reg(struct ec100_state *state, u8 reg, u8 val)
+{
+	int ret;
+	u8 buf[2] = {reg, val};
+	struct i2c_msg msg[1] = {
+		{
+			.addr = state->config.demod_address,
+			.flags = 0,
+			.len = sizeof(buf),
+			.buf = buf,
+		}
+	};
+
+	ret = i2c_transfer(state->i2c, msg, 1);
+	if (ret == 1) {
+		ret = 0;
+	} else {
+		dev_warn(&state->i2c->dev, "%s: i2c wr failed=%d reg=%02x\n",
+				KBUILD_MODNAME, ret, reg);
+		ret = -EREMOTEIO;
+	}
+
+	return ret;
+}
+
+/* read single register */
+static int ec100_read_reg(struct ec100_state *state, u8 reg, u8 *val)
+{
+	int ret;
+	struct i2c_msg msg[2] = {
+		{
+			.addr = state->config.demod_address,
+			.flags = 0,
+			.len = 1,
+			.buf = &reg
+		}, {
+			.addr = state->config.demod_address,
+			.flags = I2C_M_RD,
+			.len = 1,
+			.buf = val
+		}
+	};
+
+	ret = i2c_transfer(state->i2c, msg, 2);
+	if (ret == 2) {
+		ret = 0;
+	} else {
+		dev_warn(&state->i2c->dev, "%s: i2c rd failed=%d reg=%02x\n",
+				KBUILD_MODNAME, ret, reg);
+		ret = -EREMOTEIO;
+	}
+
+	return ret;
+}
+
+static int ec100_set_frontend(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
+	struct ec100_state *state = fe->demodulator_priv;
+	int ret;
+	u8 tmp, tmp2;
+
+	dev_dbg(&state->i2c->dev, "%s: frequency=%d bandwidth_hz=%d\n",
+			__func__, c->frequency, c->bandwidth_hz);
+
+	/* program tuner */
+	if (fe->ops.tuner_ops.set_params)
+		fe->ops.tuner_ops.set_params(fe);
+
+	ret = ec100_write_reg(state, 0x04, 0x06);
+	if (ret)
+		goto error;
+	ret = ec100_write_reg(state, 0x67, 0x58);
+	if (ret)
+		goto error;
+	ret = ec100_write_reg(state, 0x05, 0x18);
+	if (ret)
+		goto error;
+
+	/* reg/bw |   6  |   7  |   8
+	   -------+------+------+------
+	   A 0x1b | 0xa1 | 0xe7 | 0x2c
+	   A 0x1c | 0x55 | 0x63 | 0x72
+	   -------+------+------+------
+	   B 0x1b | 0xb7 | 0x00 | 0x49
+	   B 0x1c | 0x55 | 0x64 | 0x72 */
+
+	switch (c->bandwidth_hz) {
+	case 6000000:
+		tmp = 0xb7;
+		tmp2 = 0x55;
+		break;
+	case 7000000:
+		tmp = 0x00;
+		tmp2 = 0x64;
+		break;
+	case 8000000:
+	default:
+		tmp = 0x49;
+		tmp2 = 0x72;
+	}
+
+	ret = ec100_write_reg(state, 0x1b, tmp);
+	if (ret)
+		goto error;
+	ret = ec100_write_reg(state, 0x1c, tmp2);
+	if (ret)
+		goto error;
+
+	ret = ec100_write_reg(state, 0x0c, 0xbb); /* if freq */
+	if (ret)
+		goto error;
+	ret = ec100_write_reg(state, 0x0d, 0x31); /* if freq */
+	if (ret)
+		goto error;
+
+	ret = ec100_write_reg(state, 0x08, 0x24);
+	if (ret)
+		goto error;
+
+	ret = ec100_write_reg(state, 0x00, 0x00); /* go */
+	if (ret)
+		goto error;
+	ret = ec100_write_reg(state, 0x00, 0x20); /* go */
+	if (ret)
+		goto error;
+
+	return ret;
+error:
+	dev_dbg(&state->i2c->dev, "%s: failed=%d\n", __func__, ret);
+	return ret;
+}
+
+static int ec100_get_tune_settings(struct dvb_frontend *fe,
+	struct dvb_frontend_tune_settings *fesettings)
+{
+	fesettings->min_delay_ms = 300;
+	fesettings->step_size = 0;
+	fesettings->max_drift = 0;
+
+	return 0;
+}
+
+static int ec100_read_status(struct dvb_frontend *fe, enum fe_status *status)
+{
+	struct ec100_state *state = fe->demodulator_priv;
+	int ret;
+	u8 tmp;
+	*status = 0;
+
+	ret = ec100_read_reg(state, 0x42, &tmp);
+	if (ret)
+		goto error;
+
+	if (tmp & 0x80) {
+		/* bit7 set - have lock */
+		*status |= FE_HAS_SIGNAL | FE_HAS_CARRIER | FE_HAS_VITERBI |
+			FE_HAS_SYNC | FE_HAS_LOCK;
+	} else {
+		ret = ec100_read_reg(state, 0x01, &tmp);
+		if (ret)
+			goto error;
+
+		if (tmp & 0x10) {
+			/* bit4 set - have signal */
+			*status |= FE_HAS_SIGNAL;
+			if (!(tmp & 0x01)) {
+				/* bit0 clear - have ~valid signal */
+				*status |= FE_HAS_CARRIER |  FE_HAS_VITERBI;
+			}
+		}
+	}
+
+	return ret;
+error:
+	dev_dbg(&state->i2c->dev, "%s: failed=%d\n", __func__, ret);
+	return ret;
+}
+
+static int ec100_read_ber(struct dvb_frontend *fe, u32 *ber)
+{
+	struct ec100_state *state = fe->demodulator_priv;
+	int ret;
+	u8 tmp, tmp2;
+	u16 ber2;
+
+	*ber = 0;
+
+	ret = ec100_read_reg(state, 0x65, &tmp);
+	if (ret)
+		goto error;
+	ret = ec100_read_reg(state, 0x66, &tmp2);
+	if (ret)
+		goto error;
+
+	ber2 = (tmp2 << 8) | tmp;
+
+	/* if counter overflow or clear */
+	if (ber2 < state->ber)
+		*ber = ber2;
+	else
+		*ber = ber2 - state->ber;
+
+	state->ber = ber2;
+
+	return ret;
+error:
+	dev_dbg(&state->i2c->dev, "%s: failed=%d\n", __func__, ret);
+	return ret;
+}
+
+static int ec100_read_signal_strength(struct dvb_frontend *fe, u16 *strength)
+{
+	struct ec100_state *state = fe->demodulator_priv;
+	int ret;
+	u8 tmp;
+
+	ret = ec100_read_reg(state, 0x24, &tmp);
+	if (ret) {
+		*strength = 0;
+		goto error;
+	}
+
+	*strength = ((tmp << 8) | tmp);
+
+	return ret;
+error:
+	dev_dbg(&state->i2c->dev, "%s: failed=%d\n", __func__, ret);
+	return ret;
+}
+
+static int ec100_read_snr(struct dvb_frontend *fe, u16 *snr)
+{
+	*snr = 0;
+	return 0;
+}
+
+static int ec100_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)
+{
+	*ucblocks = 0;
+	return 0;
+}
+
+static void ec100_release(struct dvb_frontend *fe)
+{
+	struct ec100_state *state = fe->demodulator_priv;
+	kfree(state);
+}
+
+static const struct dvb_frontend_ops ec100_ops;
+
+struct dvb_frontend *ec100_attach(const struct ec100_config *config,
+	struct i2c_adapter *i2c)
+{
+	int ret;
+	struct ec100_state *state = NULL;
+	u8 tmp;
+
+	/* allocate memory for the internal state */
+	state = kzalloc_obj(struct ec100_state);
+	if (state == NULL)
+		goto error;
+
+	/* setup the state */
+	state->i2c = i2c;
+	memcpy(&state->config, config, sizeof(struct ec100_config));
+
+	/* check if the demod is there */
+	ret = ec100_read_reg(state, 0x33, &tmp);
+	if (ret || tmp != 0x0b)
+		goto error;
+
+	/* create dvb_frontend */
+	memcpy(&state->frontend.ops, &ec100_ops,
+		sizeof(struct dvb_frontend_ops));
+	state->frontend.demodulator_priv = state;
+
+	return &state->frontend;
+error:
+	kfree(state);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(ec100_attach);
+
+static const struct dvb_frontend_ops ec100_ops = {
+	.delsys = { SYS_DVBT },
+	.info = {
+		.name = "E3C EC100 DVB-T",
+		.caps =
+			FE_CAN_FEC_1_2 | FE_CAN_FEC_2_3 | FE_CAN_FEC_3_4 |
+			FE_CAN_FEC_5_6 | FE_CAN_FEC_7_8 | FE_CAN_FEC_AUTO |
+			FE_CAN_QPSK | FE_CAN_QAM_16 |
+			FE_CAN_QAM_64 | FE_CAN_QAM_AUTO |
+			FE_CAN_TRANSMISSION_MODE_AUTO |
+			FE_CAN_GUARD_INTERVAL_AUTO |
+			FE_CAN_HIERARCHY_AUTO |
+			FE_CAN_MUTE_TS
+	},
+
+	.release = ec100_release,
+	.set_frontend = ec100_set_frontend,
+	.get_tune_settings = ec100_get_tune_settings,
+	.read_status = ec100_read_status,
+	.read_ber = ec100_read_ber,
+	.read_signal_strength = ec100_read_signal_strength,
+	.read_snr = ec100_read_snr,
+	.read_ucblocks = ec100_read_ucblocks,
+};
+
+MODULE_AUTHOR("Antti Palosaari <crope@iki.fi>");
+MODULE_DESCRIPTION("E3C EC100 DVB-T demodulator driver");
+MODULE_LICENSE("GPL");