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, 346 insertions, 0 deletions

diff --git a/drivers/mfd/adp5520.c b/drivers/mfd/adp5520.c
new file mode 100644
index 000000000..bd6f4965e
--- /dev/null
+++ b/drivers/mfd/adp5520.c
@@ -0,0 +1,346 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Base driver for Analog Devices ADP5520/ADP5501 MFD PMICs
+ * LCD Backlight: drivers/video/backlight/adp5520_bl
+ * LEDs		: drivers/led/leds-adp5520
+ * GPIO		: drivers/gpio/adp5520-gpio (ADP5520 only)
+ * Keys		: drivers/input/keyboard/adp5520-keys (ADP5520 only)
+ *
+ * Copyright 2009 Analog Devices Inc.
+ *
+ * Author: Michael Hennerich <michael.hennerich@analog.com>
+ *
+ * Derived from da903x:
+ * Copyright (C) 2008 Compulab, Ltd.
+ *	Mike Rapoport <mike@compulab.co.il>
+ *
+ * Copyright (C) 2006-2008 Marvell International Ltd.
+ *	Eric Miao <eric.miao@marvell.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+
+#include <linux/mfd/adp5520.h>
+
+struct adp5520_chip {
+	struct i2c_client *client;
+	struct device *dev;
+	struct mutex lock;
+	struct blocking_notifier_head notifier_list;
+	int irq;
+	unsigned long id;
+	uint8_t mode;
+};
+
+static int __adp5520_read(struct i2c_client *client,
+				int reg, uint8_t *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed reading at 0x%02x\n", reg);
+		return ret;
+	}
+
+	*val = (uint8_t)ret;
+	return 0;
+}
+
+static int __adp5520_write(struct i2c_client *client,
+				 int reg, uint8_t val)
+{
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, reg, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed writing 0x%02x to 0x%02x\n",
+				val, reg);
+		return ret;
+	}
+	return 0;
+}
+
+static int __adp5520_ack_bits(struct i2c_client *client, int reg,
+			      uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = i2c_get_clientdata(client);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(client, reg, &reg_val);
+
+	if (!ret) {
+		reg_val |= bit_mask;
+		ret = __adp5520_write(client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+
+int adp5520_write(struct device *dev, int reg, uint8_t val)
+{
+	return __adp5520_write(to_i2c_client(dev), reg, val);
+}
+EXPORT_SYMBOL_GPL(adp5520_write);
+
+int adp5520_read(struct device *dev, int reg, uint8_t *val)
+{
+	return __adp5520_read(to_i2c_client(dev), reg, val);
+}
+EXPORT_SYMBOL_GPL(adp5520_read);
+
+int adp5520_set_bits(struct device *dev, int reg, uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(chip->client, reg, &reg_val);
+
+	if (!ret && ((reg_val & bit_mask) != bit_mask)) {
+		reg_val |= bit_mask;
+		ret = __adp5520_write(chip->client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adp5520_set_bits);
+
+int adp5520_clr_bits(struct device *dev, int reg, uint8_t bit_mask)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+	uint8_t reg_val;
+	int ret;
+
+	mutex_lock(&chip->lock);
+
+	ret = __adp5520_read(chip->client, reg, &reg_val);
+
+	if (!ret && (reg_val & bit_mask)) {
+		reg_val &= ~bit_mask;
+		ret = __adp5520_write(chip->client, reg, reg_val);
+	}
+
+	mutex_unlock(&chip->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(adp5520_clr_bits);
+
+int adp5520_register_notifier(struct device *dev, struct notifier_block *nb,
+				unsigned int events)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+
+	if (chip->irq) {
+		adp5520_set_bits(chip->dev, ADP5520_INTERRUPT_ENABLE,
+			events & (ADP5520_KP_IEN | ADP5520_KR_IEN |
+			ADP5520_OVP_IEN | ADP5520_CMPR_IEN));
+
+		return blocking_notifier_chain_register(&chip->notifier_list,
+			 nb);
+	}
+
+	return -ENODEV;
+}
+EXPORT_SYMBOL_GPL(adp5520_register_notifier);
+
+int adp5520_unregister_notifier(struct device *dev, struct notifier_block *nb,
+				unsigned int events)
+{
+	struct adp5520_chip *chip = dev_get_drvdata(dev);
+
+	adp5520_clr_bits(chip->dev, ADP5520_INTERRUPT_ENABLE,
+		events & (ADP5520_KP_IEN | ADP5520_KR_IEN |
+		ADP5520_OVP_IEN | ADP5520_CMPR_IEN));
+
+	return blocking_notifier_chain_unregister(&chip->notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(adp5520_unregister_notifier);
+
+static irqreturn_t adp5520_irq_thread(int irq, void *data)
+{
+	struct adp5520_chip *chip = data;
+	unsigned int events;
+	uint8_t reg_val;
+	int ret;
+
+	ret = __adp5520_read(chip->client, ADP5520_MODE_STATUS, &reg_val);
+	if (ret)
+		goto out;
+
+	events =  reg_val & (ADP5520_OVP_INT | ADP5520_CMPR_INT |
+		ADP5520_GPI_INT | ADP5520_KR_INT | ADP5520_KP_INT);
+
+	blocking_notifier_call_chain(&chip->notifier_list, events, NULL);
+	/* ACK, Sticky bits are W1C */
+	__adp5520_ack_bits(chip->client, ADP5520_MODE_STATUS, events);
+
+out:
+	return IRQ_HANDLED;
+}
+
+static int __remove_subdev(struct device *dev, void *unused)
+{
+	platform_device_unregister(to_platform_device(dev));
+	return 0;
+}
+
+static int adp5520_remove_subdevs(struct adp5520_chip *chip)
+{
+	return device_for_each_child(chip->dev, NULL, __remove_subdev);
+}
+
+static int adp5520_probe(struct i2c_client *client)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(client);
+	struct adp5520_platform_data *pdata = dev_get_platdata(&client->dev);
+	struct platform_device *pdev;
+	struct adp5520_chip *chip;
+	int ret;
+
+	if (!i2c_check_functionality(client->adapter,
+					I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_err(&client->dev, "SMBUS Word Data not Supported\n");
+		return -EIO;
+	}
+
+	if (pdata == NULL) {
+		dev_err(&client->dev, "missing platform data\n");
+		return -ENODEV;
+	}
+
+	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, chip);
+	chip->client = client;
+
+	chip->dev = &client->dev;
+	chip->irq = client->irq;
+	chip->id = id->driver_data;
+	mutex_init(&chip->lock);
+
+	if (chip->irq) {
+		BLOCKING_INIT_NOTIFIER_HEAD(&chip->notifier_list);
+
+		ret = request_threaded_irq(chip->irq, NULL, adp5520_irq_thread,
+				IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+				"adp5520", chip);
+		if (ret) {
+			dev_err(&client->dev, "failed to request irq %d\n",
+					chip->irq);
+			return ret;
+		}
+	}
+
+	ret = adp5520_write(chip->dev, ADP5520_MODE_STATUS, ADP5520_nSTNBY);
+	if (ret) {
+		dev_err(&client->dev, "failed to write\n");
+		goto out_free_irq;
+	}
+
+	if (pdata->keys) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-keys",
+				chip->id, pdata->keys, sizeof(*pdata->keys));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->gpio) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-gpio",
+				chip->id, pdata->gpio, sizeof(*pdata->gpio));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->leds) {
+		pdev = platform_device_register_data(chip->dev, "adp5520-led",
+				chip->id, pdata->leds, sizeof(*pdata->leds));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	if (pdata->backlight) {
+		pdev = platform_device_register_data(chip->dev,
+						"adp5520-backlight",
+						chip->id,
+						pdata->backlight,
+						sizeof(*pdata->backlight));
+		if (IS_ERR(pdev)) {
+			ret = PTR_ERR(pdev);
+			goto out_remove_subdevs;
+		}
+	}
+
+	return 0;
+
+out_remove_subdevs:
+	adp5520_remove_subdevs(chip);
+
+out_free_irq:
+	if (chip->irq)
+		free_irq(chip->irq, chip);
+
+	return ret;
+}
+
+static int adp5520_suspend(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct adp5520_chip *chip = dev_get_drvdata(&client->dev);
+
+	adp5520_read(chip->dev, ADP5520_MODE_STATUS, &chip->mode);
+	/* All other bits are W1C */
+	chip->mode &= ADP5520_BL_EN | ADP5520_DIM_EN | ADP5520_nSTNBY;
+	adp5520_write(chip->dev, ADP5520_MODE_STATUS, 0);
+	return 0;
+}
+
+static int adp5520_resume(struct device *dev)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct adp5520_chip *chip = dev_get_drvdata(&client->dev);
+
+	adp5520_write(chip->dev, ADP5520_MODE_STATUS, chip->mode);
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(adp5520_pm, adp5520_suspend, adp5520_resume);
+
+static const struct i2c_device_id adp5520_id[] = {
+	{ "pmic-adp5520", ID_ADP5520 },
+	{ "pmic-adp5501", ID_ADP5501 },
+	{ }
+};
+
+static struct i2c_driver adp5520_driver = {
+	.driver = {
+		.name			= "adp5520",
+		.pm			= pm_sleep_ptr(&adp5520_pm),
+		.suppress_bind_attrs	= true,
+	},
+	.probe		= adp5520_probe,
+	.id_table	= adp5520_id,
+};
+builtin_i2c_driver(adp5520_driver);