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, 143 insertions, 0 deletions

diff --git a/drivers/mfd/madera-spi.c b/drivers/mfd/madera-spi.c
new file mode 100644
index 000000000..3fffa21ce
--- /dev/null
+++ b/drivers/mfd/madera-spi.c
@@ -0,0 +1,143 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SPI bus interface to Cirrus Logic Madera codecs
+ *
+ * Copyright (C) 2015-2018 Cirrus Logic
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#include <linux/mfd/madera/core.h>
+
+#include "madera.h"
+
+static int madera_spi_probe(struct spi_device *spi)
+{
+	struct madera *madera;
+	const struct regmap_config *regmap_16bit_config = NULL;
+	const struct regmap_config *regmap_32bit_config = NULL;
+	unsigned long type;
+	const char *name;
+	int ret;
+
+	type = (unsigned long)spi_get_device_match_data(spi);
+	switch (type) {
+	case CS47L15:
+		if (IS_ENABLED(CONFIG_MFD_CS47L15)) {
+			regmap_16bit_config = &cs47l15_16bit_spi_regmap;
+			regmap_32bit_config = &cs47l15_32bit_spi_regmap;
+		}
+		break;
+	case CS47L35:
+		if (IS_ENABLED(CONFIG_MFD_CS47L35)) {
+			regmap_16bit_config = &cs47l35_16bit_spi_regmap;
+			regmap_32bit_config = &cs47l35_32bit_spi_regmap;
+		}
+		break;
+	case CS47L85:
+	case WM1840:
+		if (IS_ENABLED(CONFIG_MFD_CS47L85)) {
+			regmap_16bit_config = &cs47l85_16bit_spi_regmap;
+			regmap_32bit_config = &cs47l85_32bit_spi_regmap;
+		}
+		break;
+	case CS47L90:
+	case CS47L91:
+		if (IS_ENABLED(CONFIG_MFD_CS47L90)) {
+			regmap_16bit_config = &cs47l90_16bit_spi_regmap;
+			regmap_32bit_config = &cs47l90_32bit_spi_regmap;
+		}
+		break;
+	case CS42L92:
+	case CS47L92:
+	case CS47L93:
+		if (IS_ENABLED(CONFIG_MFD_CS47L92)) {
+			regmap_16bit_config = &cs47l92_16bit_spi_regmap;
+			regmap_32bit_config = &cs47l92_32bit_spi_regmap;
+		}
+		break;
+	default:
+		dev_err(&spi->dev,
+			"Unknown Madera SPI device type %ld\n", type);
+		return -EINVAL;
+	}
+
+	name = madera_name_from_type(type);
+
+	if (!regmap_16bit_config) {
+		/* it's polite to say which codec isn't built into the kernel */
+		dev_err(&spi->dev,
+			"Kernel does not include support for %s\n", name);
+		return -EINVAL;
+	}
+
+	madera = devm_kzalloc(&spi->dev, sizeof(*madera), GFP_KERNEL);
+	if (!madera)
+		return -ENOMEM;
+
+	madera->regmap = devm_regmap_init_spi(spi, regmap_16bit_config);
+	if (IS_ERR(madera->regmap)) {
+		ret = PTR_ERR(madera->regmap);
+		dev_err(&spi->dev,
+			"Failed to allocate 16-bit register map: %d\n",	ret);
+		return ret;
+	}
+
+	madera->regmap_32bit = devm_regmap_init_spi(spi, regmap_32bit_config);
+	if (IS_ERR(madera->regmap_32bit)) {
+		ret = PTR_ERR(madera->regmap_32bit);
+		dev_err(&spi->dev,
+			"Failed to allocate 32-bit register map: %d\n",	ret);
+		return ret;
+	}
+
+	madera->type = type;
+	madera->type_name = name;
+	madera->dev = &spi->dev;
+	madera->irq = spi->irq;
+
+	return madera_dev_init(madera);
+}
+
+static void madera_spi_remove(struct spi_device *spi)
+{
+	struct madera *madera = spi_get_drvdata(spi);
+
+	madera_dev_exit(madera);
+}
+
+static const struct spi_device_id madera_spi_ids[] = {
+	{ .name = "cs47l15", .driver_data = CS47L15 },
+	{ .name = "cs47l35", .driver_data = CS47L35 },
+	{ .name = "cs47l85", .driver_data = CS47L85 },
+	{ .name = "cs47l90", .driver_data = CS47L90 },
+	{ .name = "cs47l91", .driver_data = CS47L91 },
+	{ .name = "cs42l92", .driver_data = CS42L92 },
+	{ .name = "cs47l92", .driver_data = CS47L92 },
+	{ .name = "cs47l93", .driver_data = CS47L93 },
+	{ .name = "wm1840", .driver_data = WM1840 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, madera_spi_ids);
+
+static struct spi_driver madera_spi_driver = {
+	.driver = {
+		.name	= "madera",
+		.pm	= &madera_pm_ops,
+		.of_match_table	= of_match_ptr(madera_of_match),
+	},
+	.probe		= madera_spi_probe,
+	.remove		= madera_spi_remove,
+	.id_table	= madera_spi_ids,
+};
+
+module_spi_driver(madera_spi_driver);
+
+MODULE_DESCRIPTION("Madera SPI bus interface");
+MODULE_AUTHOR("Richard Fitzgerald <rf@opensource.cirrus.com>");
+MODULE_LICENSE("GPL v2");