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, 406 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/elo.c b/drivers/input/touchscreen/elo.c
new file mode 100644
index 000000000..97aeec7ef
--- /dev/null
+++ b/drivers/input/touchscreen/elo.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Elo serial touchscreen driver
+ *
+ * Copyright (c) 2004 Vojtech Pavlik
+ */
+
+
+/*
+ * This driver can handle serial Elo touchscreens using either the Elo standard
+ * 'E271-2210' 10-byte protocol, Elo legacy 'E281A-4002' 6-byte protocol, Elo
+ * legacy 'E271-140' 4-byte protocol and Elo legacy 'E261-280' 3-byte protocol.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/ctype.h>
+
+#define DRIVER_DESC	"Elo serial touchscreen driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define ELO_MAX_LENGTH		10
+
+#define ELO10_PACKET_LEN	8
+#define ELO10_TOUCH		0x03
+#define ELO10_PRESSURE		0x80
+
+#define ELO10_LEAD_BYTE		'U'
+
+#define ELO10_ID_CMD		'i'
+
+#define ELO10_TOUCH_PACKET	'T'
+#define ELO10_ACK_PACKET	'A'
+#define ELI10_ID_PACKET		'I'
+
+/*
+ * Per-touchscreen data.
+ */
+
+struct elo {
+	struct input_dev *dev;
+	struct serio *serio;
+	struct mutex cmd_mutex;
+	struct completion cmd_done;
+	int id;
+	int idx;
+	unsigned char expected_packet;
+	unsigned char csum;
+	unsigned char data[ELO_MAX_LENGTH];
+	unsigned char response[ELO10_PACKET_LEN];
+	char phys[32];
+};
+
+static void elo_process_data_10(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+	case 0:
+		elo->csum = 0xaa;
+		if (data != ELO10_LEAD_BYTE) {
+			dev_dbg(&elo->serio->dev,
+				"unsynchronized data: 0x%02x\n", data);
+			elo->idx = 0;
+		}
+		break;
+
+	case 9:
+		elo->idx = 0;
+		if (data != elo->csum) {
+			dev_dbg(&elo->serio->dev,
+				"bad checksum: 0x%02x, expected 0x%02x\n",
+				 data, elo->csum);
+			break;
+		}
+		if (elo->data[1] != elo->expected_packet) {
+			if (elo->data[1] != ELO10_TOUCH_PACKET)
+				dev_dbg(&elo->serio->dev,
+					"unexpected packet: 0x%02x\n",
+					 elo->data[1]);
+			break;
+		}
+		if (likely(elo->data[1] == ELO10_TOUCH_PACKET)) {
+			input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
+			input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
+			if (elo->data[2] & ELO10_PRESSURE)
+				input_report_abs(dev, ABS_PRESSURE,
+						(elo->data[8] << 8) | elo->data[7]);
+			input_report_key(dev, BTN_TOUCH, elo->data[2] & ELO10_TOUCH);
+			input_sync(dev);
+		} else if (elo->data[1] == ELO10_ACK_PACKET) {
+			if (elo->data[2] == '0')
+				elo->expected_packet = ELO10_TOUCH_PACKET;
+			complete(&elo->cmd_done);
+		} else {
+			memcpy(elo->response, &elo->data[1], ELO10_PACKET_LEN);
+			elo->expected_packet = ELO10_ACK_PACKET;
+		}
+		break;
+	}
+	elo->csum += data;
+}
+
+static void elo_process_data_6(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+
+	case 0:
+		if ((data & 0xc0) != 0xc0)
+			elo->idx = 0;
+		break;
+
+	case 1:
+		if ((data & 0xc0) != 0x80)
+			elo->idx = 0;
+		break;
+
+	case 2:
+		if ((data & 0xc0) != 0x40)
+			elo->idx = 0;
+		break;
+
+	case 3:
+		if (data & 0xc0) {
+			elo->idx = 0;
+			break;
+		}
+
+		input_report_abs(dev, ABS_X, ((elo->data[0] & 0x3f) << 6) | (elo->data[1] & 0x3f));
+		input_report_abs(dev, ABS_Y, ((elo->data[2] & 0x3f) << 6) | (elo->data[3] & 0x3f));
+
+		if (elo->id == 2) {
+			input_report_key(dev, BTN_TOUCH, 1);
+			input_sync(dev);
+			elo->idx = 0;
+		}
+
+		break;
+
+	case 4:
+		if (data) {
+			input_sync(dev);
+			elo->idx = 0;
+		}
+		break;
+
+	case 5:
+		if ((data & 0xf0) == 0) {
+			input_report_abs(dev, ABS_PRESSURE, elo->data[5]);
+			input_report_key(dev, BTN_TOUCH, !!elo->data[5]);
+		}
+		input_sync(dev);
+		elo->idx = 0;
+		break;
+	}
+}
+
+static void elo_process_data_3(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+
+	case 0:
+		if ((data & 0x7f) != 0x01)
+			elo->idx = 0;
+		break;
+	case 2:
+		input_report_key(dev, BTN_TOUCH, !(elo->data[1] & 0x80));
+		input_report_abs(dev, ABS_X, elo->data[1]);
+		input_report_abs(dev, ABS_Y, elo->data[2]);
+		input_sync(dev);
+		elo->idx = 0;
+		break;
+	}
+}
+
+static irqreturn_t elo_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct elo *elo = serio_get_drvdata(serio);
+
+	switch (elo->id) {
+	case 0:
+		elo_process_data_10(elo, data);
+		break;
+
+	case 1:
+	case 2:
+		elo_process_data_6(elo, data);
+		break;
+
+	case 3:
+		elo_process_data_3(elo, data);
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int elo_command_10(struct elo *elo, unsigned char *packet)
+{
+	int error;
+	int i;
+	unsigned char csum = 0xaa + ELO10_LEAD_BYTE;
+
+	guard(mutex)(&elo->cmd_mutex);
+
+	scoped_guard(serio_pause_rx, elo->serio) {
+		elo->expected_packet = toupper(packet[0]);
+		init_completion(&elo->cmd_done);
+	}
+
+	error = serio_write(elo->serio, ELO10_LEAD_BYTE);
+	if (error)
+		return error;
+
+	for (i = 0; i < ELO10_PACKET_LEN; i++) {
+		csum += packet[i];
+		error = serio_write(elo->serio, packet[i]);
+		if (error)
+			return error;
+	}
+
+	error = serio_write(elo->serio, csum);
+	if (error)
+		return error;
+
+	wait_for_completion_timeout(&elo->cmd_done, HZ);
+
+	if (elo->expected_packet != ELO10_TOUCH_PACKET)
+		return -EIO;
+
+	/* We are back in reporting mode, the command was ACKed */
+	memcpy(packet, elo->response, ELO10_PACKET_LEN);
+	return 0;
+}
+
+static int elo_setup_10(struct elo *elo)
+{
+	static const char * const elo_types[] = { "Accu", "Dura", "Intelli", "Carroll" };
+	struct input_dev *dev = elo->dev;
+	unsigned char packet[ELO10_PACKET_LEN] = { ELO10_ID_CMD };
+
+	if (elo_command_10(elo, packet))
+		return -1;
+
+	dev->id.version = (packet[5] << 8) | packet[4];
+
+	input_set_abs_params(dev, ABS_X, 96, 4000, 0, 0);
+	input_set_abs_params(dev, ABS_Y, 96, 4000, 0, 0);
+	if (packet[3] & ELO10_PRESSURE)
+		input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);
+
+	dev_info(&elo->serio->dev,
+		 "%sTouch touchscreen, fw: %02x.%02x, features: 0x%02x, controller: 0x%02x\n",
+		 elo_types[(packet[1] - '0') & 0x03],
+		 packet[5], packet[4], packet[3], packet[7]);
+
+	return 0;
+}
+
+/*
+ * elo_disconnect() is the opposite of elo_connect()
+ */
+
+static void elo_disconnect(struct serio *serio)
+{
+	struct elo *elo = serio_get_drvdata(serio);
+
+	input_get_device(elo->dev);
+	input_unregister_device(elo->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_put_device(elo->dev);
+	kfree(elo);
+}
+
+/*
+ * elo_connect() is the routine that is called when someone adds a
+ * new serio device that supports Gunze protocol and registers it as
+ * an input device.
+ */
+
+static int elo_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct elo *elo;
+	struct input_dev *input_dev;
+	int err;
+
+	elo = kzalloc_obj(*elo);
+	input_dev = input_allocate_device();
+	if (!elo || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	elo->serio = serio;
+	elo->id = serio->id.id;
+	elo->dev = input_dev;
+	elo->expected_packet = ELO10_TOUCH_PACKET;
+	mutex_init(&elo->cmd_mutex);
+	init_completion(&elo->cmd_done);
+	scnprintf(elo->phys, sizeof(elo->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "Elo Serial TouchScreen";
+	input_dev->phys = elo->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_ELO;
+	input_dev->id.product = elo->id;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+
+	serio_set_drvdata(serio, elo);
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	switch (elo->id) {
+
+	case 0: /* 10-byte protocol */
+		if (elo_setup_10(elo)) {
+			err = -EIO;
+			goto fail3;
+		}
+
+		break;
+
+	case 1: /* 6-byte protocol */
+		input_set_abs_params(input_dev, ABS_PRESSURE, 0, 15, 0, 0);
+		fallthrough;
+
+	case 2: /* 4-byte protocol */
+		input_set_abs_params(input_dev, ABS_X, 96, 4000, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, 96, 4000, 0, 0);
+		break;
+
+	case 3: /* 3-byte protocol */
+		input_set_abs_params(input_dev, ABS_X, 0, 255, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, 0, 255, 0, 0);
+		break;
+	}
+
+	err = input_register_device(elo->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3: serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(elo);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id elo_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_ELO,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, elo_serio_ids);
+
+static struct serio_driver elo_drv = {
+	.driver		= {
+		.name	= "elo",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= elo_serio_ids,
+	.interrupt	= elo_interrupt,
+	.connect	= elo_connect,
+	.disconnect	= elo_disconnect,
+};
+
+module_serio_driver(elo_drv);