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, 87 insertions, 0 deletions

diff --git a/drivers/mfd/lp873x.c b/drivers/mfd/lp873x.c
new file mode 100644
index 000000000..d2c90302b
--- /dev/null
+++ b/drivers/mfd/lp873x.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016 Texas Instruments Incorporated - https://www.ti.com/
+ *
+ * Author: Keerthy <j-keerthy@ti.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/lp873x.h>
+
+static const struct regmap_config lp873x_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LP873X_REG_MAX,
+};
+
+static const struct mfd_cell lp873x_cells[] = {
+	{ .name = "lp873x-regulator", },
+	{ .name = "lp873x-gpio", },
+};
+
+static int lp873x_probe(struct i2c_client *client)
+{
+	struct lp873x *lp873;
+	int ret;
+	unsigned int otpid;
+
+	lp873 = devm_kzalloc(&client->dev, sizeof(*lp873), GFP_KERNEL);
+	if (!lp873)
+		return -ENOMEM;
+
+	lp873->dev = &client->dev;
+
+	lp873->regmap = devm_regmap_init_i2c(client, &lp873x_regmap_config);
+	if (IS_ERR(lp873->regmap)) {
+		ret = PTR_ERR(lp873->regmap);
+		dev_err(lp873->dev,
+			"Failed to initialize register map: %d\n", ret);
+		return ret;
+	}
+
+	ret = regmap_read(lp873->regmap, LP873X_REG_OTP_REV, &otpid);
+	if (ret) {
+		dev_err(lp873->dev, "Failed to read OTP ID\n");
+		return ret;
+	}
+
+	lp873->rev = otpid & LP873X_OTP_REV_OTP_ID;
+
+	i2c_set_clientdata(client, lp873);
+
+	ret = mfd_add_devices(lp873->dev, PLATFORM_DEVID_AUTO, lp873x_cells,
+			      ARRAY_SIZE(lp873x_cells), NULL, 0, NULL);
+
+	return ret;
+}
+
+static const struct of_device_id of_lp873x_match_table[] = {
+	{ .compatible = "ti,lp8733", },
+	{ .compatible = "ti,lp8732", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, of_lp873x_match_table);
+
+static const struct i2c_device_id lp873x_id_table[] = {
+	{ "lp873x" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, lp873x_id_table);
+
+static struct i2c_driver lp873x_driver = {
+	.driver	= {
+		.name	= "lp873x",
+		.of_match_table = of_lp873x_match_table,
+	},
+	.probe		= lp873x_probe,
+	.id_table	= lp873x_id_table,
+};
+module_i2c_driver(lp873x_driver);
+
+MODULE_AUTHOR("J Keerthy <j-keerthy@ti.com>");
+MODULE_DESCRIPTION("LP873X chip family Multi-Function Device driver");
+MODULE_LICENSE("GPL v2");