KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.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");