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, 242 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/stb6000.c b/drivers/media/dvb-frontends/stb6000.c
new file mode 100644
index 000000000..c66d4ac17
--- /dev/null
+++ b/drivers/media/dvb-frontends/stb6000.c
@@ -0,0 +1,242 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+  /*
+     Driver for ST STB6000 DVBS Silicon tuner
+
+     Copyright (C) 2008 Igor M. Liplianin (liplianin@me.by)
+
+
+  */
+
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/dvb/frontend.h>
+#include <asm/types.h>
+
+#include "stb6000.h"
+
+static int debug;
+#define dprintk(args...) \
+	do { \
+		if (debug) \
+			printk(KERN_DEBUG "stb6000: " args); \
+	} while (0)
+
+struct stb6000_priv {
+	/* i2c details */
+	int i2c_address;
+	struct i2c_adapter *i2c;
+	u32 frequency;
+};
+
+static void stb6000_release(struct dvb_frontend *fe)
+{
+	kfree(fe->tuner_priv);
+	fe->tuner_priv = NULL;
+}
+
+static int stb6000_sleep(struct dvb_frontend *fe)
+{
+	struct stb6000_priv *priv = fe->tuner_priv;
+	int ret;
+	u8 buf[] = { 10, 0 };
+	struct i2c_msg msg = {
+		.addr = priv->i2c_address,
+		.flags = 0,
+		.buf = buf,
+		.len = 2
+	};
+
+	dprintk("%s:\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+
+	ret = i2c_transfer(priv->i2c, &msg, 1);
+	if (ret != 1)
+		dprintk("%s: i2c error\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 0);
+
+	return (ret == 1) ? 0 : ret;
+}
+
+static int stb6000_set_params(struct dvb_frontend *fe)
+{
+	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
+	struct stb6000_priv *priv = fe->tuner_priv;
+	unsigned int n, m;
+	int ret;
+	u32 freq_mhz;
+	int bandwidth;
+	u8 buf[12];
+	struct i2c_msg msg = {
+		.addr = priv->i2c_address,
+		.flags = 0,
+		.buf = buf,
+		.len = 12
+	};
+
+	dprintk("%s:\n", __func__);
+
+	freq_mhz = p->frequency / 1000;
+	bandwidth = p->symbol_rate / 1000000;
+
+	if (bandwidth > 31)
+		bandwidth = 31;
+
+	if ((freq_mhz > 949) && (freq_mhz < 2151)) {
+		buf[0] = 0x01;
+		buf[1] = 0xac;
+		if (freq_mhz < 1950)
+			buf[1] = 0xaa;
+		if (freq_mhz < 1800)
+			buf[1] = 0xa8;
+		if (freq_mhz < 1650)
+			buf[1] = 0xa6;
+		if (freq_mhz < 1530)
+			buf[1] = 0xa5;
+		if (freq_mhz < 1470)
+			buf[1] = 0xa4;
+		if (freq_mhz < 1370)
+			buf[1] = 0xa2;
+		if (freq_mhz < 1300)
+			buf[1] = 0xa1;
+		if (freq_mhz < 1200)
+			buf[1] = 0xa0;
+		if (freq_mhz < 1075)
+			buf[1] = 0xbc;
+		if (freq_mhz < 1000)
+			buf[1] = 0xba;
+		if (freq_mhz < 1075) {
+			n = freq_mhz / 8; /* vco=lo*4 */
+			m = 2;
+		} else {
+			n = freq_mhz / 16; /* vco=lo*2 */
+			m = 1;
+		}
+		buf[2] = n >> 1;
+		buf[3] = (unsigned char)(((n & 1) << 7) |
+					(m * freq_mhz - n * 16) | 0x60);
+		buf[4] = 0x04;
+		buf[5] = 0x0e;
+
+		buf[6] = (unsigned char)(bandwidth);
+
+		buf[7] = 0xd8;
+		buf[8] = 0xd0;
+		buf[9] = 0x50;
+		buf[10] = 0xeb;
+		buf[11] = 0x4f;
+
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 1);
+
+		ret = i2c_transfer(priv->i2c, &msg, 1);
+		if (ret != 1)
+			dprintk("%s: i2c error\n", __func__);
+
+		udelay(10);
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 0);
+
+		buf[0] = 0x07;
+		buf[1] = 0xdf;
+		buf[2] = 0xd0;
+		buf[3] = 0x50;
+		buf[4] = 0xfb;
+		msg.len = 5;
+
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 1);
+
+		ret = i2c_transfer(priv->i2c, &msg, 1);
+		if (ret != 1)
+			dprintk("%s: i2c error\n", __func__);
+
+		udelay(10);
+		if (fe->ops.i2c_gate_ctrl)
+			fe->ops.i2c_gate_ctrl(fe, 0);
+
+		priv->frequency = freq_mhz * 1000;
+
+		return (ret == 1) ? 0 : ret;
+	}
+	return -1;
+}
+
+static int stb6000_get_frequency(struct dvb_frontend *fe, u32 *frequency)
+{
+	struct stb6000_priv *priv = fe->tuner_priv;
+	*frequency = priv->frequency;
+	return 0;
+}
+
+static const struct dvb_tuner_ops stb6000_tuner_ops = {
+	.info = {
+		.name = "ST STB6000",
+		.frequency_min_hz =  950 * MHz,
+		.frequency_max_hz = 2150 * MHz
+	},
+	.release = stb6000_release,
+	.sleep = stb6000_sleep,
+	.set_params = stb6000_set_params,
+	.get_frequency = stb6000_get_frequency,
+};
+
+struct dvb_frontend *stb6000_attach(struct dvb_frontend *fe, int addr,
+						struct i2c_adapter *i2c)
+{
+	struct stb6000_priv *priv = NULL;
+	u8 b0[] = { 0 };
+	u8 b1[] = { 0, 0 };
+	struct i2c_msg msg[2] = {
+		{
+			.addr = addr,
+			.flags = 0,
+			.buf = b0,
+			.len = 0
+		}, {
+			.addr = addr,
+			.flags = I2C_M_RD,
+			.buf = b1,
+			.len = 2
+		}
+	};
+	int ret;
+
+	dprintk("%s:\n", __func__);
+
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 1);
+
+	/* is some i2c device here ? */
+	ret = i2c_transfer(i2c, msg, 2);
+	if (fe->ops.i2c_gate_ctrl)
+		fe->ops.i2c_gate_ctrl(fe, 0);
+
+	if (ret != 2)
+		return NULL;
+
+	priv = kzalloc_obj(struct stb6000_priv);
+	if (priv == NULL)
+		return NULL;
+
+	priv->i2c_address = addr;
+	priv->i2c = i2c;
+
+	memcpy(&fe->ops.tuner_ops, &stb6000_tuner_ops,
+				sizeof(struct dvb_tuner_ops));
+
+	fe->tuner_priv = priv;
+
+	return fe;
+}
+EXPORT_SYMBOL_GPL(stb6000_attach);
+
+module_param(debug, int, 0644);
+MODULE_PARM_DESC(debug, "Turn on/off frontend debugging (default:off).");
+
+MODULE_DESCRIPTION("DVB STB6000 driver");
+MODULE_AUTHOR("Igor M. Liplianin <liplianin@me.by>");
+MODULE_LICENSE("GPL");