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, 220 insertions, 0 deletions

diff --git a/drivers/mfd/max77541.c b/drivers/mfd/max77541.c
new file mode 100644
index 000000000..f91b4f537
--- /dev/null
+++ b/drivers/mfd/max77541.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 Analog Devices, Inc.
+ * Driver for the MAX77540 and MAX77541
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77541.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+static const struct regmap_config max77541_regmap_config = {
+	.reg_bits   = 8,
+	.val_bits   = 8,
+};
+
+static const struct regmap_irq max77541_src_irqs[] = {
+	{ .mask = MAX77541_BIT_INT_SRC_TOPSYS },
+	{ .mask = MAX77541_BIT_INT_SRC_BUCK },
+};
+
+static const struct regmap_irq_chip max77541_src_irq_chip = {
+	.name		= "max77541-src",
+	.status_base	= MAX77541_REG_INT_SRC,
+	.mask_base	= MAX77541_REG_INT_SRC_M,
+	.num_regs	= 1,
+	.irqs		= max77541_src_irqs,
+	.num_irqs       = ARRAY_SIZE(max77541_src_irqs),
+};
+
+static const struct regmap_irq max77541_topsys_irqs[] = {
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TJ_120C },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TJ_140C },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TSHDN },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_UVLO },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_ALT_SWO },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_EXT_FREQ_DET },
+};
+
+static const struct regmap_irq_chip max77541_topsys_irq_chip = {
+	.name		= "max77541-topsys",
+	.status_base	= MAX77541_REG_TOPSYS_INT,
+	.mask_base	= MAX77541_REG_TOPSYS_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_topsys_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_topsys_irqs),
+};
+
+static const struct regmap_irq max77541_buck_irqs[] = {
+	{ .mask = MAX77541_BIT_BUCK_INT_M1_POK_FLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M2_POK_FLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M1_SCFLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M2_SCFLT },
+};
+
+static const struct regmap_irq_chip max77541_buck_irq_chip = {
+	.name		= "max77541-buck",
+	.status_base	= MAX77541_REG_BUCK_INT,
+	.mask_base	= MAX77541_REG_BUCK_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_buck_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_buck_irqs),
+};
+
+static const struct regmap_irq max77541_adc_irqs[] = {
+	{ .mask = MAX77541_BIT_ADC_INT_CH1_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH2_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH3_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH6_I },
+};
+
+static const struct regmap_irq_chip max77541_adc_irq_chip = {
+	.name		= "max77541-adc",
+	.status_base	= MAX77541_REG_ADC_INT,
+	.mask_base	= MAX77541_REG_ADC_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_adc_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_adc_irqs),
+};
+
+static const struct mfd_cell max77540_devs[] = {
+	MFD_CELL_OF("max77540-regulator", NULL, NULL, 0, 0, NULL),
+};
+
+static const struct mfd_cell max77541_devs[] = {
+	MFD_CELL_OF("max77541-regulator", NULL, NULL, 0, 0, NULL),
+	MFD_CELL_OF("max77541-adc", NULL, NULL, 0, 0, NULL),
+};
+
+static int max77541_pmic_irq_init(struct device *dev)
+{
+	struct max77541 *max77541 = dev_get_drvdata(dev);
+	int irq = max77541->i2c->irq;
+	int ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_src_irq_chip,
+				       &max77541->irq_data);
+	if (ret)
+		return ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_topsys_irq_chip,
+				       &max77541->irq_topsys);
+	if (ret)
+		return ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_buck_irq_chip,
+				       &max77541->irq_buck);
+	if (ret)
+		return ret;
+
+	if (max77541->id == MAX77541) {
+		ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+					       IRQF_ONESHOT | IRQF_SHARED, 0,
+					       &max77541_adc_irq_chip,
+					       &max77541->irq_adc);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int max77541_pmic_setup(struct device *dev)
+{
+	struct max77541 *max77541 = dev_get_drvdata(dev);
+	const struct mfd_cell *cells;
+	int n_devs;
+	int ret;
+
+	switch (max77541->id) {
+	case MAX77540:
+		cells =  max77540_devs;
+		n_devs = ARRAY_SIZE(max77540_devs);
+		break;
+	case MAX77541:
+		cells =  max77541_devs;
+		n_devs = ARRAY_SIZE(max77541_devs);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = max77541_pmic_irq_init(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize IRQ\n");
+
+	ret = devm_device_init_wakeup(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Unable to init wakeup\n");
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				    cells, n_devs, NULL, 0, NULL);
+}
+
+static int max77541_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct max77541 *max77541;
+
+	max77541 = devm_kzalloc(dev, sizeof(*max77541), GFP_KERNEL);
+	if (!max77541)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, max77541);
+	max77541->i2c = client;
+
+	max77541->id = (uintptr_t)i2c_get_match_data(client);
+	if (!max77541->id)
+		return -EINVAL;
+
+	max77541->regmap = devm_regmap_init_i2c(client,
+						&max77541_regmap_config);
+	if (IS_ERR(max77541->regmap))
+		return dev_err_probe(dev, PTR_ERR(max77541->regmap),
+				     "Failed to allocate register map\n");
+
+	return max77541_pmic_setup(dev);
+}
+
+static const struct of_device_id max77541_of_id[] = {
+	{
+		.compatible = "adi,max77540",
+		.data = (void *)MAX77540,
+	},
+	{
+		.compatible = "adi,max77541",
+		.data = (void *)MAX77541,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77541_of_id);
+
+static const struct i2c_device_id max77541_id[] = {
+	{ "max77540", MAX77540 },
+	{ "max77541", MAX77541 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max77541_id);
+
+static struct i2c_driver max77541_driver = {
+	.driver = {
+		.name = "max77541",
+		.of_match_table = max77541_of_id,
+	},
+	.probe = max77541_probe,
+	.id_table = max77541_id,
+};
+module_i2c_driver(max77541_driver);
+
+MODULE_DESCRIPTION("MAX7740/MAX7741 Driver");
+MODULE_AUTHOR("Okan Sahin <okan.sahin@analog.com>");
+MODULE_LICENSE("GPL");