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, 244 insertions, 0 deletions

diff --git a/drivers/mfd/stpmic1.c b/drivers/mfd/stpmic1.c
new file mode 100644
index 000000000..7c677b034
--- /dev/null
+++ b/drivers/mfd/stpmic1.c
@@ -0,0 +1,244 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) STMicroelectronics 2018
+// Author: Pascal Paillet <p.paillet@st.com>
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/stpmic1.h>
+#include <linux/module.h>
+#include <linux/reboot.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/pm_wakeirq.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/mfd/st,stpmic1.h>
+
+#define STPMIC1_MAX_RETRIES 2
+
+#define STPMIC1_MAIN_IRQ 0
+
+static const struct regmap_range stpmic1_readable_ranges[] = {
+	regmap_reg_range(TURN_ON_SR, VERSION_SR),
+	regmap_reg_range(MAIN_CR, LDO6_STDBY_CR),
+	regmap_reg_range(BST_SW_CR, BST_SW_CR),
+	regmap_reg_range(INT_PENDING_R1, INT_PENDING_R4),
+	regmap_reg_range(INT_CLEAR_R1, INT_CLEAR_R4),
+	regmap_reg_range(INT_MASK_R1, INT_MASK_R4),
+	regmap_reg_range(INT_SET_MASK_R1, INT_SET_MASK_R4),
+	regmap_reg_range(INT_CLEAR_MASK_R1, INT_CLEAR_MASK_R4),
+	regmap_reg_range(INT_SRC_R1, INT_SRC_R1),
+};
+
+static const struct regmap_range stpmic1_writeable_ranges[] = {
+	regmap_reg_range(MAIN_CR, LDO6_STDBY_CR),
+	regmap_reg_range(BST_SW_CR, BST_SW_CR),
+	regmap_reg_range(INT_CLEAR_R1, INT_CLEAR_R4),
+	regmap_reg_range(INT_SET_MASK_R1, INT_SET_MASK_R4),
+	regmap_reg_range(INT_CLEAR_MASK_R1, INT_CLEAR_MASK_R4),
+};
+
+static const struct regmap_range stpmic1_volatile_ranges[] = {
+	regmap_reg_range(TURN_ON_SR, VERSION_SR),
+	regmap_reg_range(WCHDG_CR, WCHDG_CR),
+	regmap_reg_range(INT_PENDING_R1, INT_PENDING_R4),
+	regmap_reg_range(INT_SRC_R1, INT_SRC_R4),
+};
+
+static const struct regmap_access_table stpmic1_readable_table = {
+	.yes_ranges = stpmic1_readable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_readable_ranges),
+};
+
+static const struct regmap_access_table stpmic1_writeable_table = {
+	.yes_ranges = stpmic1_writeable_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_writeable_ranges),
+};
+
+static const struct regmap_access_table stpmic1_volatile_table = {
+	.yes_ranges = stpmic1_volatile_ranges,
+	.n_yes_ranges = ARRAY_SIZE(stpmic1_volatile_ranges),
+};
+
+static const struct regmap_config stpmic1_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.cache_type = REGCACHE_MAPLE,
+	.max_register = PMIC_MAX_REGISTER_ADDRESS,
+	.rd_table = &stpmic1_readable_table,
+	.wr_table = &stpmic1_writeable_table,
+	.volatile_table = &stpmic1_volatile_table,
+};
+
+static const struct regmap_irq stpmic1_irqs[] = {
+	REGMAP_IRQ_REG(IT_PONKEY_F, 0, 0x01),
+	REGMAP_IRQ_REG(IT_PONKEY_R, 0, 0x02),
+	REGMAP_IRQ_REG(IT_WAKEUP_F, 0, 0x04),
+	REGMAP_IRQ_REG(IT_WAKEUP_R, 0, 0x08),
+	REGMAP_IRQ_REG(IT_VBUS_OTG_F, 0, 0x10),
+	REGMAP_IRQ_REG(IT_VBUS_OTG_R, 0, 0x20),
+	REGMAP_IRQ_REG(IT_SWOUT_F, 0, 0x40),
+	REGMAP_IRQ_REG(IT_SWOUT_R, 0, 0x80),
+
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK1, 1, 0x01),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK2, 1, 0x02),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK3, 1, 0x04),
+	REGMAP_IRQ_REG(IT_CURLIM_BUCK4, 1, 0x08),
+	REGMAP_IRQ_REG(IT_OCP_OTG, 1, 0x10),
+	REGMAP_IRQ_REG(IT_OCP_SWOUT, 1, 0x20),
+	REGMAP_IRQ_REG(IT_OCP_BOOST, 1, 0x40),
+	REGMAP_IRQ_REG(IT_OVP_BOOST, 1, 0x80),
+
+	REGMAP_IRQ_REG(IT_CURLIM_LDO1, 2, 0x01),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO2, 2, 0x02),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO3, 2, 0x04),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO4, 2, 0x08),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO5, 2, 0x10),
+	REGMAP_IRQ_REG(IT_CURLIM_LDO6, 2, 0x20),
+	REGMAP_IRQ_REG(IT_SHORT_SWOTG, 2, 0x40),
+	REGMAP_IRQ_REG(IT_SHORT_SWOUT, 2, 0x80),
+
+	REGMAP_IRQ_REG(IT_TWARN_F, 3, 0x01),
+	REGMAP_IRQ_REG(IT_TWARN_R, 3, 0x02),
+	REGMAP_IRQ_REG(IT_VINLOW_F, 3, 0x04),
+	REGMAP_IRQ_REG(IT_VINLOW_R, 3, 0x08),
+	REGMAP_IRQ_REG(IT_SWIN_F, 3, 0x40),
+	REGMAP_IRQ_REG(IT_SWIN_R, 3, 0x80),
+};
+
+static const struct regmap_irq_chip stpmic1_regmap_irq_chip = {
+	.name = "pmic_irq",
+	.status_base = INT_PENDING_R1,
+	.mask_base = INT_SET_MASK_R1,
+	.unmask_base = INT_CLEAR_MASK_R1,
+	.mask_unmask_non_inverted = true,
+	.ack_base = INT_CLEAR_R1,
+	.num_regs = STPMIC1_PMIC_NUM_IRQ_REGS,
+	.irqs = stpmic1_irqs,
+	.num_irqs = ARRAY_SIZE(stpmic1_irqs),
+};
+
+static int stpmic1_power_off(struct sys_off_data *data)
+{
+	struct stpmic1 *ddata = data->cb_data;
+	int ret;
+
+	/*
+	 * Attempt to shut down again, in case the first attempt failed.
+	 * The STPMIC1 might get confused and the first regmap_update_bits()
+	 * returns with -ETIMEDOUT / -110 . If that or similar transient
+	 * failure occurs, try to shut down again. If the second attempt
+	 * fails, there is some bigger problem, report it to user.
+	 */
+	for (int retries = 0; retries < STPMIC1_MAX_RETRIES; retries++) {
+		ret = regmap_update_bits(ddata->regmap, MAIN_CR, SOFTWARE_SWITCH_OFF,
+					 SOFTWARE_SWITCH_OFF);
+		if (!ret)
+			return NOTIFY_DONE;
+	}
+
+	dev_err(ddata->dev, "Failed to access PMIC I2C bus (%d)\n", ret);
+
+	return NOTIFY_DONE;
+}
+
+static int stpmic1_probe(struct i2c_client *i2c)
+{
+	struct stpmic1 *ddata;
+	struct device *dev = &i2c->dev;
+	int ret;
+	struct device_node *np = dev->of_node;
+	u32 reg;
+
+	ddata = devm_kzalloc(dev, sizeof(struct stpmic1), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, ddata);
+	ddata->dev = dev;
+
+	ddata->regmap = devm_regmap_init_i2c(i2c, &stpmic1_regmap_config);
+	if (IS_ERR(ddata->regmap))
+		return PTR_ERR(ddata->regmap);
+
+	ddata->irq = of_irq_get(np, STPMIC1_MAIN_IRQ);
+	if (ddata->irq < 0) {
+		dev_err(dev, "Failed to get main IRQ: %d\n", ddata->irq);
+		return ddata->irq;
+	}
+
+	ret = regmap_read(ddata->regmap, VERSION_SR, &reg);
+	if (ret) {
+		dev_err(dev, "Unable to read PMIC version\n");
+		return ret;
+	}
+	dev_info(dev, "PMIC Chip Version: 0x%x\n", reg);
+
+	/* Initialize PMIC IRQ Chip & associated IRQ domains */
+	ret = devm_regmap_add_irq_chip(dev, ddata->regmap, ddata->irq,
+				       IRQF_ONESHOT | IRQF_SHARED,
+				       0, &stpmic1_regmap_irq_chip,
+				       &ddata->irq_data);
+	if (ret) {
+		dev_err(dev, "IRQ Chip registration failed: %d\n", ret);
+		return ret;
+	}
+
+	ret = devm_register_power_off_handler(ddata->dev, stpmic1_power_off, ddata);
+	if (ret) {
+		dev_err(ddata->dev, "failed to register sys-off handler: %d\n", ret);
+		return ret;
+	}
+
+	return devm_of_platform_populate(dev);
+}
+
+static int stpmic1_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct stpmic1 *pmic_dev = i2c_get_clientdata(i2c);
+
+	disable_irq(pmic_dev->irq);
+
+	return 0;
+}
+
+static int stpmic1_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct stpmic1 *pmic_dev = i2c_get_clientdata(i2c);
+	int ret;
+
+	ret = regcache_sync(pmic_dev->regmap);
+	if (ret)
+		return ret;
+
+	enable_irq(pmic_dev->irq);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(stpmic1_pm, stpmic1_suspend, stpmic1_resume);
+
+static const struct of_device_id stpmic1_of_match[] = {
+	{ .compatible = "st,stpmic1", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, stpmic1_of_match);
+
+static struct i2c_driver stpmic1_driver = {
+	.driver = {
+		.name = "stpmic1",
+		.of_match_table = stpmic1_of_match,
+		.pm = pm_sleep_ptr(&stpmic1_pm),
+	},
+	.probe = stpmic1_probe,
+};
+
+module_i2c_driver(stpmic1_driver);
+
+MODULE_DESCRIPTION("STPMIC1 PMIC Driver");
+MODULE_AUTHOR("Pascal Paillet <p.paillet@st.com>");
+MODULE_LICENSE("GPL v2");