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, 338 insertions, 0 deletions

diff --git a/drivers/mfd/max8907.c b/drivers/mfd/max8907.c
new file mode 100644
index 000000000..7bac1d651
--- /dev/null
+++ b/drivers/mfd/max8907.c
@@ -0,0 +1,338 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * max8907.c - mfd driver for MAX8907
+ *
+ * Copyright (C) 2010 Gyungoh Yoo <jack.yoo@maxim-ic.com>
+ * Copyright (C) 2010-2012, NVIDIA CORPORATION. All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max8907.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+static const struct mfd_cell max8907_cells[] = {
+	{ .name = "max8907-regulator", },
+	{ .name = "max8907-rtc", },
+};
+
+static bool max8907_gen_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_ON_OFF_IRQ1:
+	case MAX8907_REG_ON_OFF_STAT:
+	case MAX8907_REG_ON_OFF_IRQ2:
+	case MAX8907_REG_CHG_IRQ1:
+	case MAX8907_REG_CHG_IRQ2:
+	case MAX8907_REG_CHG_STAT:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_gen_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_ON_OFF_IRQ1:
+	case MAX8907_REG_ON_OFF_IRQ2:
+	case MAX8907_REG_CHG_IRQ1:
+	case MAX8907_REG_CHG_IRQ2:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_gen_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	return !max8907_gen_is_volatile_reg(dev, reg);
+}
+
+static const struct regmap_config max8907_regmap_gen_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = max8907_gen_is_volatile_reg,
+	.precious_reg = max8907_gen_is_precious_reg,
+	.writeable_reg = max8907_gen_is_writeable_reg,
+	.max_register = MAX8907_REG_LDO20VOUT,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static bool max8907_rtc_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	if (reg <= MAX8907_REG_RTC_YEAR2)
+		return true;
+
+	switch (reg) {
+	case MAX8907_REG_RTC_STATUS:
+	case MAX8907_REG_RTC_IRQ:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_rtc_is_precious_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_RTC_IRQ:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool max8907_rtc_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case MAX8907_REG_RTC_STATUS:
+	case MAX8907_REG_RTC_IRQ:
+		return false;
+	default:
+		return true;
+	}
+}
+
+static const struct regmap_config max8907_regmap_rtc_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.volatile_reg = max8907_rtc_is_volatile_reg,
+	.precious_reg = max8907_rtc_is_precious_reg,
+	.writeable_reg = max8907_rtc_is_writeable_reg,
+	.max_register = MAX8907_REG_MPL_CNTL,
+	.cache_type = REGCACHE_MAPLE,
+};
+
+static const struct regmap_irq max8907_chg_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 0, },
+	{ .reg_offset = 0, .mask = 1 << 1, },
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 1, .mask = 1 << 0, },
+	{ .reg_offset = 1, .mask = 1 << 1, },
+	{ .reg_offset = 1, .mask = 1 << 2, },
+	{ .reg_offset = 1, .mask = 1 << 3, },
+	{ .reg_offset = 1, .mask = 1 << 4, },
+	{ .reg_offset = 1, .mask = 1 << 5, },
+	{ .reg_offset = 1, .mask = 1 << 6, },
+	{ .reg_offset = 1, .mask = 1 << 7, },
+};
+
+static const struct regmap_irq_chip max8907_chg_irq_chip = {
+	.name = "max8907 chg",
+	.status_base = MAX8907_REG_CHG_IRQ1,
+	.mask_base = MAX8907_REG_CHG_IRQ1_MASK,
+	.wake_base = MAX8907_REG_CHG_IRQ1_MASK,
+	.irq_reg_stride = MAX8907_REG_CHG_IRQ2 - MAX8907_REG_CHG_IRQ1,
+	.num_regs = 2,
+	.irqs = max8907_chg_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_chg_irqs),
+};
+
+static const struct regmap_irq max8907_on_off_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 0, },
+	{ .reg_offset = 0, .mask = 1 << 1, },
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 0, .mask = 1 << 3, },
+	{ .reg_offset = 0, .mask = 1 << 4, },
+	{ .reg_offset = 0, .mask = 1 << 5, },
+	{ .reg_offset = 0, .mask = 1 << 6, },
+	{ .reg_offset = 0, .mask = 1 << 7, },
+	{ .reg_offset = 1, .mask = 1 << 0, },
+	{ .reg_offset = 1, .mask = 1 << 1, },
+};
+
+static const struct regmap_irq_chip max8907_on_off_irq_chip = {
+	.name = "max8907 on_off",
+	.status_base = MAX8907_REG_ON_OFF_IRQ1,
+	.mask_base = MAX8907_REG_ON_OFF_IRQ1_MASK,
+	.irq_reg_stride = MAX8907_REG_ON_OFF_IRQ2 - MAX8907_REG_ON_OFF_IRQ1,
+	.num_regs = 2,
+	.irqs = max8907_on_off_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_on_off_irqs),
+};
+
+static const struct regmap_irq max8907_rtc_irqs[] = {
+	{ .reg_offset = 0, .mask = 1 << 2, },
+	{ .reg_offset = 0, .mask = 1 << 3, },
+};
+
+static const struct regmap_irq_chip max8907_rtc_irq_chip = {
+	.name = "max8907 rtc",
+	.status_base = MAX8907_REG_RTC_IRQ,
+	.mask_base = MAX8907_REG_RTC_IRQ_MASK,
+	.num_regs = 1,
+	.irqs = max8907_rtc_irqs,
+	.num_irqs = ARRAY_SIZE(max8907_rtc_irqs),
+};
+
+static struct max8907 *max8907_pm_off;
+static void max8907_power_off(void)
+{
+	regmap_update_bits(max8907_pm_off->regmap_gen, MAX8907_REG_RESET_CNFG,
+			MAX8907_MASK_POWER_OFF, MAX8907_MASK_POWER_OFF);
+}
+
+static int max8907_i2c_probe(struct i2c_client *i2c)
+{
+	struct max8907 *max8907;
+	int ret;
+	struct max8907_platform_data *pdata = dev_get_platdata(&i2c->dev);
+	bool pm_off = false;
+
+	if (pdata)
+		pm_off = pdata->pm_off;
+	else if (i2c->dev.of_node)
+		pm_off = of_property_read_bool(i2c->dev.of_node,
+					"maxim,system-power-controller");
+
+	max8907 = devm_kzalloc(&i2c->dev, sizeof(struct max8907), GFP_KERNEL);
+	if (!max8907) {
+		ret = -ENOMEM;
+		goto err_alloc_drvdata;
+	}
+
+	max8907->dev = &i2c->dev;
+	max8907->i2c_gen = i2c;
+	i2c_set_clientdata(i2c, max8907);
+	max8907->regmap_gen = devm_regmap_init_i2c(i2c,
+						&max8907_regmap_gen_config);
+	if (IS_ERR(max8907->regmap_gen)) {
+		ret = PTR_ERR(max8907->regmap_gen);
+		dev_err(&i2c->dev, "gen regmap init failed: %d\n", ret);
+		goto err_regmap_gen;
+	}
+
+	max8907->i2c_rtc = i2c_new_dummy_device(i2c->adapter, MAX8907_RTC_I2C_ADDR);
+	if (IS_ERR(max8907->i2c_rtc)) {
+		ret = PTR_ERR(max8907->i2c_rtc);
+		goto err_dummy_rtc;
+	}
+	i2c_set_clientdata(max8907->i2c_rtc, max8907);
+	max8907->regmap_rtc = devm_regmap_init_i2c(max8907->i2c_rtc,
+						&max8907_regmap_rtc_config);
+	if (IS_ERR(max8907->regmap_rtc)) {
+		ret = PTR_ERR(max8907->regmap_rtc);
+		dev_err(&i2c->dev, "rtc regmap init failed: %d\n", ret);
+		goto err_regmap_rtc;
+	}
+
+	ret = regmap_add_irq_chip(max8907->regmap_gen, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED,
+				  -1, &max8907_chg_irq_chip,
+				  &max8907->irqc_chg);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add chg irq chip: %d\n", ret);
+		goto err_irqc_chg;
+	}
+	ret = regmap_add_irq_chip(max8907->regmap_gen, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED, -1,
+				  &max8907_on_off_irq_chip,
+				  &max8907->irqc_on_off);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add on off irq chip: %d\n", ret);
+		goto err_irqc_on_off;
+	}
+	ret = regmap_add_irq_chip(max8907->regmap_rtc, max8907->i2c_gen->irq,
+				  IRQF_ONESHOT | IRQF_SHARED, -1,
+				  &max8907_rtc_irq_chip,
+				  &max8907->irqc_rtc);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add rtc irq chip: %d\n", ret);
+		goto err_irqc_rtc;
+	}
+
+	ret = mfd_add_devices(max8907->dev, -1, max8907_cells,
+			      ARRAY_SIZE(max8907_cells), NULL, 0, NULL);
+	if (ret != 0) {
+		dev_err(&i2c->dev, "failed to add MFD devices %d\n", ret);
+		goto err_add_devices;
+	}
+
+	if (pm_off && !pm_power_off) {
+		max8907_pm_off = max8907;
+		pm_power_off = max8907_power_off;
+	}
+
+	return 0;
+
+err_add_devices:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_rtc);
+err_irqc_rtc:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_on_off);
+err_irqc_on_off:
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_chg);
+err_irqc_chg:
+err_regmap_rtc:
+	i2c_unregister_device(max8907->i2c_rtc);
+err_dummy_rtc:
+err_regmap_gen:
+err_alloc_drvdata:
+	return ret;
+}
+
+static void max8907_i2c_remove(struct i2c_client *i2c)
+{
+	struct max8907 *max8907 = i2c_get_clientdata(i2c);
+
+	mfd_remove_devices(max8907->dev);
+
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_rtc);
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_on_off);
+	regmap_del_irq_chip(max8907->i2c_gen->irq, max8907->irqc_chg);
+
+	i2c_unregister_device(max8907->i2c_rtc);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id max8907_of_match[] = {
+	{ .compatible = "maxim,max8907" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, max8907_of_match);
+#endif
+
+static const struct i2c_device_id max8907_i2c_id[] = {
+	{ "max8907" },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, max8907_i2c_id);
+
+static struct i2c_driver max8907_i2c_driver = {
+	.driver = {
+		.name = "max8907",
+		.of_match_table = of_match_ptr(max8907_of_match),
+	},
+	.probe = max8907_i2c_probe,
+	.remove = max8907_i2c_remove,
+	.id_table = max8907_i2c_id,
+};
+
+static int __init max8907_i2c_init(void)
+{
+	int ret = -ENODEV;
+
+	ret = i2c_add_driver(&max8907_i2c_driver);
+	if (ret != 0)
+		pr_err("Failed to register I2C driver: %d\n", ret);
+
+	return ret;
+}
+subsys_initcall(max8907_i2c_init);
+
+static void __exit max8907_i2c_exit(void)
+{
+	i2c_del_driver(&max8907_i2c_driver);
+}
+module_exit(max8907_i2c_exit);
+
+MODULE_DESCRIPTION("MAX8907 multi-function core driver");
+MODULE_AUTHOR("Gyungoh Yoo <jack.yoo@maxim-ic.com>");
+MODULE_LICENSE("GPL v2");