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, 376 insertions, 0 deletions

diff --git a/drivers/input/keyboard/sunkbd.c b/drivers/input/keyboard/sunkbd.c
new file mode 100644
index 000000000..5a0020827
--- /dev/null
+++ b/drivers/input/keyboard/sunkbd.c
@@ -0,0 +1,376 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1999-2001 Vojtech Pavlik
+ */
+
+/*
+ * Sun keyboard driver for Linux
+ */
+
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/workqueue.h>
+
+#define DRIVER_DESC	"Sun keyboard driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+static unsigned char sunkbd_keycode[128] = {
+	  0,128,114,129,115, 59, 60, 68, 61, 87, 62, 88, 63,100, 64,112,
+	 65, 66, 67, 56,103,119, 99, 70,105,130,131,108,106,  1,  2,  3,
+	  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 41, 14,110,113, 98, 55,
+	116,132, 83,133,102, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
+	 26, 27,111,127, 71, 72, 73, 74,134,135,107,  0, 29, 30, 31, 32,
+	 33, 34, 35, 36, 37, 38, 39, 40, 43, 28, 96, 75, 76, 77, 82,136,
+	104,137, 69, 42, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54,101,
+	 79, 80, 81,  0,  0,  0,138, 58,125, 57,126,109, 86, 78
+};
+
+#define SUNKBD_CMD_RESET	0x1
+#define SUNKBD_CMD_BELLON	0x2
+#define SUNKBD_CMD_BELLOFF	0x3
+#define SUNKBD_CMD_CLICK	0xa
+#define SUNKBD_CMD_NOCLICK	0xb
+#define SUNKBD_CMD_SETLED	0xe
+#define SUNKBD_CMD_LAYOUT	0xf
+
+#define SUNKBD_RET_RESET	0xff
+#define SUNKBD_RET_ALLUP	0x7f
+#define SUNKBD_RET_LAYOUT	0xfe
+
+#define SUNKBD_LAYOUT_5_MASK	0x20
+#define SUNKBD_RELEASE		0x80
+#define SUNKBD_KEY		0x7f
+
+/*
+ * Per-keyboard data.
+ */
+
+struct sunkbd {
+	unsigned char keycode[ARRAY_SIZE(sunkbd_keycode)];
+	struct input_dev *dev;
+	struct serio *serio;
+	struct work_struct tq;
+	wait_queue_head_t wait;
+	char name[64];
+	char phys[32];
+	char type;
+	bool enabled;
+	volatile s8 reset;
+	volatile s8 layout;
+};
+
+/*
+ * sunkbd_interrupt() is called by the low level driver when a character
+ * is received.
+ */
+
+static irqreturn_t sunkbd_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct sunkbd *sunkbd = serio_get_drvdata(serio);
+
+	if (sunkbd->reset <= -1) {
+		/*
+		 * If cp[i] is 0xff, sunkbd->reset will stay -1.
+		 * The keyboard sends 0xff 0xff 0xID on powerup.
+		 */
+		sunkbd->reset = data;
+		wake_up_interruptible(&sunkbd->wait);
+		goto out;
+	}
+
+	if (sunkbd->layout == -1) {
+		sunkbd->layout = data;
+		wake_up_interruptible(&sunkbd->wait);
+		goto out;
+	}
+
+	switch (data) {
+
+	case SUNKBD_RET_RESET:
+		if (sunkbd->enabled)
+			schedule_work(&sunkbd->tq);
+		sunkbd->reset = -1;
+		break;
+
+	case SUNKBD_RET_LAYOUT:
+		sunkbd->layout = -1;
+		break;
+
+	case SUNKBD_RET_ALLUP: /* All keys released */
+		break;
+
+	default:
+		if (!sunkbd->enabled)
+			break;
+
+		if (sunkbd->keycode[data & SUNKBD_KEY]) {
+			input_report_key(sunkbd->dev,
+					 sunkbd->keycode[data & SUNKBD_KEY],
+					 !(data & SUNKBD_RELEASE));
+			input_sync(sunkbd->dev);
+		} else {
+			printk(KERN_WARNING
+				"sunkbd.c: Unknown key (scancode %#x) %s.\n",
+				data & SUNKBD_KEY,
+				data & SUNKBD_RELEASE ? "released" : "pressed");
+		}
+	}
+out:
+	return IRQ_HANDLED;
+}
+
+/*
+ * sunkbd_event() handles events from the input module.
+ */
+
+static int sunkbd_event(struct input_dev *dev,
+			unsigned int type, unsigned int code, int value)
+{
+	struct sunkbd *sunkbd = input_get_drvdata(dev);
+
+	switch (type) {
+
+	case EV_LED:
+
+		serio_write(sunkbd->serio, SUNKBD_CMD_SETLED);
+		serio_write(sunkbd->serio,
+			(!!test_bit(LED_CAPSL,   dev->led) << 3) |
+			(!!test_bit(LED_SCROLLL, dev->led) << 2) |
+			(!!test_bit(LED_COMPOSE, dev->led) << 1) |
+			 !!test_bit(LED_NUML,    dev->led));
+		return 0;
+
+	case EV_SND:
+
+		switch (code) {
+
+		case SND_CLICK:
+			serio_write(sunkbd->serio, SUNKBD_CMD_NOCLICK - value);
+			return 0;
+
+		case SND_BELL:
+			serio_write(sunkbd->serio, SUNKBD_CMD_BELLOFF - value);
+			return 0;
+		}
+
+		break;
+	}
+
+	return -1;
+}
+
+/*
+ * sunkbd_initialize() checks for a Sun keyboard attached, and determines
+ * its type.
+ */
+
+static int sunkbd_initialize(struct sunkbd *sunkbd)
+{
+	sunkbd->reset = -2;
+	serio_write(sunkbd->serio, SUNKBD_CMD_RESET);
+	wait_event_interruptible_timeout(sunkbd->wait, sunkbd->reset >= 0, HZ);
+	if (sunkbd->reset < 0)
+		return -1;
+
+	sunkbd->type = sunkbd->reset;
+
+	if (sunkbd->type == 4) {	/* Type 4 keyboard */
+		sunkbd->layout = -2;
+		serio_write(sunkbd->serio, SUNKBD_CMD_LAYOUT);
+		wait_event_interruptible_timeout(sunkbd->wait,
+						 sunkbd->layout >= 0, HZ / 4);
+		if (sunkbd->layout < 0)
+			return -1;
+		if (sunkbd->layout & SUNKBD_LAYOUT_5_MASK)
+			sunkbd->type = 5;
+	}
+
+	return 0;
+}
+
+/*
+ * sunkbd_set_leds_beeps() sets leds and beeps to a state the computer remembers
+ * they were in.
+ */
+
+static void sunkbd_set_leds_beeps(struct sunkbd *sunkbd)
+{
+	serio_write(sunkbd->serio, SUNKBD_CMD_SETLED);
+	serio_write(sunkbd->serio,
+		(!!test_bit(LED_CAPSL,   sunkbd->dev->led) << 3) |
+		(!!test_bit(LED_SCROLLL, sunkbd->dev->led) << 2) |
+		(!!test_bit(LED_COMPOSE, sunkbd->dev->led) << 1) |
+		 !!test_bit(LED_NUML,    sunkbd->dev->led));
+	serio_write(sunkbd->serio,
+		SUNKBD_CMD_NOCLICK - !!test_bit(SND_CLICK, sunkbd->dev->snd));
+	serio_write(sunkbd->serio,
+		SUNKBD_CMD_BELLOFF - !!test_bit(SND_BELL, sunkbd->dev->snd));
+}
+
+
+/*
+ * sunkbd_reinit() wait for the keyboard reset to complete and restores state
+ * of leds and beeps.
+ */
+
+static void sunkbd_reinit(struct work_struct *work)
+{
+	struct sunkbd *sunkbd = container_of(work, struct sunkbd, tq);
+
+	/*
+	 * It is OK that we check sunkbd->enabled without pausing serio,
+	 * as we only want to catch true->false transition that will
+	 * happen once and we will be woken up for it.
+	 */
+	wait_event_interruptible_timeout(sunkbd->wait,
+					 sunkbd->reset >= 0 || !sunkbd->enabled,
+					 HZ);
+
+	if (sunkbd->reset >= 0 && sunkbd->enabled)
+		sunkbd_set_leds_beeps(sunkbd);
+}
+
+static void sunkbd_enable(struct sunkbd *sunkbd, bool enable)
+{
+	scoped_guard(serio_pause_rx, sunkbd->serio)
+		sunkbd->enabled = enable;
+
+	if (!enable) {
+		wake_up_interruptible(&sunkbd->wait);
+		cancel_work_sync(&sunkbd->tq);
+	}
+}
+
+/*
+ * sunkbd_connect() probes for a Sun keyboard and fills the necessary
+ * structures.
+ */
+
+static int sunkbd_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct sunkbd *sunkbd;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+	int i;
+
+	sunkbd = kzalloc_obj(*sunkbd);
+	input_dev = input_allocate_device();
+	if (!sunkbd || !input_dev)
+		goto fail1;
+
+	sunkbd->serio = serio;
+	sunkbd->dev = input_dev;
+	init_waitqueue_head(&sunkbd->wait);
+	INIT_WORK(&sunkbd->tq, sunkbd_reinit);
+	snprintf(sunkbd->phys, sizeof(sunkbd->phys), "%s/input0", serio->phys);
+
+	serio_set_drvdata(serio, sunkbd);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	if (sunkbd_initialize(sunkbd) < 0) {
+		err = -ENODEV;
+		goto fail3;
+	}
+
+	snprintf(sunkbd->name, sizeof(sunkbd->name),
+		 "Sun Type %d keyboard", sunkbd->type);
+	memcpy(sunkbd->keycode, sunkbd_keycode, sizeof(sunkbd->keycode));
+
+	input_dev->name = sunkbd->name;
+	input_dev->phys = sunkbd->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor  = SERIO_SUNKBD;
+	input_dev->id.product = sunkbd->type;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_set_drvdata(input_dev, sunkbd);
+
+	input_dev->event = sunkbd_event;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_LED) |
+		BIT_MASK(EV_SND) | BIT_MASK(EV_REP);
+	input_dev->ledbit[0] = BIT_MASK(LED_CAPSL) | BIT_MASK(LED_COMPOSE) |
+		BIT_MASK(LED_SCROLLL) | BIT_MASK(LED_NUML);
+	input_dev->sndbit[0] = BIT_MASK(SND_CLICK) | BIT_MASK(SND_BELL);
+
+	input_dev->keycode = sunkbd->keycode;
+	input_dev->keycodesize = sizeof(unsigned char);
+	input_dev->keycodemax = ARRAY_SIZE(sunkbd_keycode);
+	for (i = 0; i < ARRAY_SIZE(sunkbd_keycode); i++)
+		__set_bit(sunkbd->keycode[i], input_dev->keybit);
+	__clear_bit(KEY_RESERVED, input_dev->keybit);
+
+	sunkbd_enable(sunkbd, true);
+
+	err = input_register_device(sunkbd->dev);
+	if (err)
+		goto fail4;
+
+	return 0;
+
+ fail4:	sunkbd_enable(sunkbd, false);
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(sunkbd);
+	return err;
+}
+
+/*
+ * sunkbd_disconnect() unregisters and closes behind us.
+ */
+
+static void sunkbd_disconnect(struct serio *serio)
+{
+	struct sunkbd *sunkbd = serio_get_drvdata(serio);
+
+	sunkbd_enable(sunkbd, false);
+	input_unregister_device(sunkbd->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	kfree(sunkbd);
+}
+
+static const struct serio_device_id sunkbd_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_SUNKBD,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_UNKNOWN, /* sunkbd does probe */
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, sunkbd_serio_ids);
+
+static struct serio_driver sunkbd_drv = {
+	.driver		= {
+		.name	= "sunkbd",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= sunkbd_serio_ids,
+	.interrupt	= sunkbd_interrupt,
+	.connect	= sunkbd_connect,
+	.disconnect	= sunkbd_disconnect,
+};
+
+module_serio_driver(sunkbd_drv);