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, 226 insertions, 0 deletions

diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
new file mode 100644
index 000000000..b08d1d08d
--- /dev/null
+++ b/drivers/input/input-leds.c
@@ -0,0 +1,226 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * LED support for the input layer
+ *
+ * Copyright 2010-2015 Samuel Thibault <samuel.thibault@ens-lyon.org>
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/leds.h>
+#include <linux/input.h>
+
+#if IS_ENABLED(CONFIG_VT)
+#define VT_TRIGGER(_name)	.trigger = _name
+#else
+#define VT_TRIGGER(_name)	.trigger = NULL
+#endif
+
+#if IS_ENABLED(CONFIG_SND_CTL_LED)
+#define AUDIO_TRIGGER(_name)	.trigger = _name
+#else
+#define AUDIO_TRIGGER(_name)	.trigger = NULL
+#endif
+
+static const struct {
+	const char *name;
+	const char *trigger;
+} input_led_info[LED_CNT] = {
+	[LED_NUML]	= { "numlock", VT_TRIGGER("kbd-numlock") },
+	[LED_CAPSL]	= { "capslock", VT_TRIGGER("kbd-capslock") },
+	[LED_SCROLLL]	= { "scrolllock", VT_TRIGGER("kbd-scrolllock") },
+	[LED_COMPOSE]	= { "compose" },
+	[LED_KANA]	= { "kana", VT_TRIGGER("kbd-kanalock") },
+	[LED_SLEEP]	= { "sleep" } ,
+	[LED_SUSPEND]	= { "suspend" },
+	[LED_MUTE]	= { "mute", AUDIO_TRIGGER("audio-mute") },
+	[LED_MISC]	= { "misc" },
+	[LED_MAIL]	= { "mail" },
+	[LED_CHARGING]	= { "charging" },
+};
+
+struct input_led {
+	struct led_classdev cdev;
+	struct input_handle *handle;
+	unsigned int code; /* One of LED_* constants */
+};
+
+struct input_leds {
+	struct input_handle handle;
+	unsigned int num_leds;
+	struct input_led leds[] __counted_by(num_leds);
+};
+
+static enum led_brightness input_leds_brightness_get(struct led_classdev *cdev)
+{
+	struct input_led *led = container_of(cdev, struct input_led, cdev);
+	struct input_dev *input = led->handle->dev;
+
+	return test_bit(led->code, input->led) ? cdev->max_brightness : 0;
+}
+
+static void input_leds_brightness_set(struct led_classdev *cdev,
+				      enum led_brightness brightness)
+{
+	struct input_led *led = container_of(cdev, struct input_led, cdev);
+
+	input_inject_event(led->handle, EV_LED, led->code, !!brightness);
+}
+
+static void input_leds_event(struct input_handle *handle, unsigned int type,
+			     unsigned int code, int value)
+{
+}
+
+static int input_leds_get_count(struct input_dev *dev)
+{
+	unsigned int led_code;
+	int count = 0;
+
+	for_each_set_bit(led_code, dev->ledbit, LED_CNT)
+		if (input_led_info[led_code].name)
+			count++;
+
+	return count;
+}
+
+static int input_leds_connect(struct input_handler *handler,
+			      struct input_dev *dev,
+			      const struct input_device_id *id)
+{
+	struct input_leds *leds;
+	struct input_led *led;
+	unsigned int num_leds;
+	unsigned int led_code;
+	int led_no;
+	int error;
+
+	num_leds = input_leds_get_count(dev);
+	if (!num_leds)
+		return -ENXIO;
+
+	leds = kzalloc_flex(*leds, leds, num_leds);
+	if (!leds)
+		return -ENOMEM;
+
+	leds->num_leds = num_leds;
+
+	leds->handle.dev = dev;
+	leds->handle.handler = handler;
+	leds->handle.name = "leds";
+	leds->handle.private = leds;
+
+	error = input_register_handle(&leds->handle);
+	if (error)
+		goto err_free_mem;
+
+	error = input_open_device(&leds->handle);
+	if (error)
+		goto err_unregister_handle;
+
+	led_no = 0;
+	for_each_set_bit(led_code, dev->ledbit, LED_CNT) {
+		if (!input_led_info[led_code].name)
+			continue;
+
+		led = &leds->leds[led_no];
+		led->handle = &leds->handle;
+		led->code = led_code;
+
+		led->cdev.name = kasprintf(GFP_KERNEL, "%s::%s",
+					   dev_name(&dev->dev),
+					   input_led_info[led_code].name);
+		if (!led->cdev.name) {
+			error = -ENOMEM;
+			goto err_unregister_leds;
+		}
+
+		led->cdev.max_brightness = 1;
+		led->cdev.brightness_get = input_leds_brightness_get;
+		led->cdev.brightness_set = input_leds_brightness_set;
+		led->cdev.default_trigger = input_led_info[led_code].trigger;
+
+		error = led_classdev_register(&dev->dev, &led->cdev);
+		if (error) {
+			dev_err(&dev->dev, "failed to register LED %s: %d\n",
+				led->cdev.name, error);
+			kfree(led->cdev.name);
+			goto err_unregister_leds;
+		}
+
+		led_no++;
+	}
+
+	return 0;
+
+err_unregister_leds:
+	while (--led_no >= 0) {
+		struct input_led *led = &leds->leds[led_no];
+
+		led_classdev_unregister(&led->cdev);
+		kfree(led->cdev.name);
+	}
+
+	input_close_device(&leds->handle);
+
+err_unregister_handle:
+	input_unregister_handle(&leds->handle);
+
+err_free_mem:
+	kfree(leds);
+	return error;
+}
+
+static void input_leds_disconnect(struct input_handle *handle)
+{
+	struct input_leds *leds = handle->private;
+	int i;
+
+	for (i = 0; i < leds->num_leds; i++) {
+		struct input_led *led = &leds->leds[i];
+
+		led_classdev_unregister(&led->cdev);
+		kfree(led->cdev.name);
+	}
+
+	input_close_device(handle);
+	input_unregister_handle(handle);
+
+	kfree(leds);
+}
+
+static const struct input_device_id input_leds_ids[] = {
+	{
+		.flags = INPUT_DEVICE_ID_MATCH_EVBIT,
+		.evbit = { BIT_MASK(EV_LED) },
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(input, input_leds_ids);
+
+static struct input_handler input_leds_handler = {
+	.event =	input_leds_event,
+	.connect =	input_leds_connect,
+	.disconnect =	input_leds_disconnect,
+	.name =		"leds",
+	.id_table =	input_leds_ids,
+};
+
+static int __init input_leds_init(void)
+{
+	return input_register_handler(&input_leds_handler);
+}
+module_init(input_leds_init);
+
+static void __exit input_leds_exit(void)
+{
+	input_unregister_handler(&input_leds_handler);
+}
+module_exit(input_leds_exit);
+
+MODULE_AUTHOR("Samuel Thibault <samuel.thibault@ens-lyon.org>");
+MODULE_AUTHOR("Dmitry Torokhov <dmitry.torokhov@gmail.com>");
+MODULE_DESCRIPTION("Input -> LEDs Bridge");
+MODULE_LICENSE("GPL v2");