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, 217 insertions, 0 deletions

diff --git a/drivers/mfd/max77843.c b/drivers/mfd/max77843.c
new file mode 100644
index 000000000..2a48577b1
--- /dev/null
+++ b/drivers/mfd/max77843.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// MFD core driver for the Maxim MAX77843
+//
+// Copyright (C) 2015 Samsung Electronics
+// Author: Jaewon Kim <jaewon02.kim@samsung.com>
+// Author: Beomho Seo <beomho.seo@samsung.com>
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77693-common.h>
+#include <linux/mfd/max77843-private.h>
+#include <linux/platform_device.h>
+
+static const struct mfd_cell max77843_devs[] = {
+	{
+		.name = "max77843-muic",
+		.of_compatible = "maxim,max77843-muic",
+	}, {
+		.name = "max77843-regulator",
+		.of_compatible = "maxim,max77843-regulator",
+	}, {
+		.name = "max77843-charger",
+		.of_compatible = "maxim,max77843-charger"
+	}, {
+		.name = "max77843-fuelgauge",
+		.of_compatible = "maxim,max77843-fuelgauge",
+	}, {
+		.name = "max77843-haptic",
+		.of_compatible = "maxim,max77843-haptic",
+	},
+};
+
+static const struct regmap_config max77843_charger_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_CHG_REG_END,
+};
+
+static const struct regmap_config max77843_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_SYS_REG_END,
+};
+
+static const struct regmap_irq max77843_irqs[] = {
+	/* TOPSYS interrupts */
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSUVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSOVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TSHDN_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TM_INT, },
+};
+
+static const struct regmap_irq_chip max77843_irq_chip = {
+	.name		= "max77843",
+	.status_base	= MAX77843_SYS_REG_SYSINTSRC,
+	.mask_base	= MAX77843_SYS_REG_SYSINTMASK,
+	.num_regs	= 1,
+	.irqs		= max77843_irqs,
+	.num_irqs	= ARRAY_SIZE(max77843_irqs),
+};
+
+/* Charger and Charger regulator use same regmap. */
+static int max77843_chg_init(struct max77693_dev *max77843)
+{
+	int ret;
+
+	max77843->i2c_chg = i2c_new_dummy_device(max77843->i2c->adapter, I2C_ADDR_CHG);
+	if (IS_ERR(max77843->i2c_chg)) {
+		dev_err(&max77843->i2c->dev,
+				"Cannot allocate I2C device for Charger\n");
+		return PTR_ERR(max77843->i2c_chg);
+	}
+	i2c_set_clientdata(max77843->i2c_chg, max77843);
+
+	max77843->regmap_chg = devm_regmap_init_i2c(max77843->i2c_chg,
+			&max77843_charger_regmap_config);
+	if (IS_ERR(max77843->regmap_chg)) {
+		ret = PTR_ERR(max77843->regmap_chg);
+		goto err_chg_i2c;
+	}
+
+	return 0;
+
+err_chg_i2c:
+	i2c_unregister_device(max77843->i2c_chg);
+
+	return ret;
+}
+
+static int max77843_probe(struct i2c_client *i2c)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(i2c);
+	struct max77693_dev *max77843;
+	unsigned int reg_data;
+	int ret;
+
+	max77843 = devm_kzalloc(&i2c->dev, sizeof(*max77843), GFP_KERNEL);
+	if (!max77843)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, max77843);
+	max77843->dev = &i2c->dev;
+	max77843->i2c = i2c;
+	max77843->irq = i2c->irq;
+	max77843->type = id->driver_data;
+
+	max77843->regmap = devm_regmap_init_i2c(i2c,
+			&max77843_regmap_config);
+	if (IS_ERR(max77843->regmap)) {
+		dev_err(&i2c->dev, "Failed to allocate topsys register map\n");
+		return PTR_ERR(max77843->regmap);
+	}
+
+	ret = regmap_add_irq_chip(max77843->regmap, max77843->irq,
+			IRQF_TRIGGER_LOW | IRQF_ONESHOT | IRQF_SHARED,
+			0, &max77843_irq_chip, &max77843->irq_data_topsys);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to add TOPSYS IRQ chip\n");
+		return ret;
+	}
+
+	ret = regmap_read(max77843->regmap,
+			MAX77843_SYS_REG_PMICID, &reg_data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to read PMIC ID\n");
+		goto err_pmic_id;
+	}
+	dev_info(&i2c->dev, "device ID: 0x%x\n", reg_data);
+
+	ret = max77843_chg_init(max77843);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to init Charger\n");
+		goto err_pmic_id;
+	}
+
+	ret = regmap_update_bits(max77843->regmap,
+				 MAX77843_SYS_REG_INTSRCMASK,
+				 MAX77843_INTSRC_MASK_MASK,
+				 (unsigned int)~MAX77843_INTSRC_MASK_MASK);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to unmask interrupt source\n");
+		goto err_pmic_id;
+	}
+
+	ret = mfd_add_devices(max77843->dev, -1, max77843_devs,
+			      ARRAY_SIZE(max77843_devs), NULL, 0, NULL);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to add mfd device\n");
+		goto err_pmic_id;
+	}
+
+	device_init_wakeup(max77843->dev, true);
+
+	return 0;
+
+err_pmic_id:
+	regmap_del_irq_chip(max77843->irq, max77843->irq_data_topsys);
+
+	return ret;
+}
+
+static const struct of_device_id max77843_dt_match[] = {
+	{ .compatible = "maxim,max77843", },
+	{ },
+};
+
+static const struct i2c_device_id max77843_id[] = {
+	{ "max77843", TYPE_MAX77843, },
+	{ },
+};
+
+static int __maybe_unused max77843_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	disable_irq(max77843->irq);
+	if (device_may_wakeup(dev))
+		enable_irq_wake(max77843->irq);
+
+	return 0;
+}
+
+static int __maybe_unused max77843_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(max77843->irq);
+	enable_irq(max77843->irq);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(max77843_pm, max77843_suspend, max77843_resume);
+
+static struct i2c_driver max77843_i2c_driver = {
+	.driver	= {
+		.name = "max77843",
+		.pm = &max77843_pm,
+		.of_match_table = max77843_dt_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = max77843_probe,
+	.id_table = max77843_id,
+};
+
+static int __init max77843_i2c_init(void)
+{
+	return i2c_add_driver(&max77843_i2c_driver);
+}
+subsys_initcall(max77843_i2c_init);