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, 115 insertions, 0 deletions

diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
new file mode 100644
index 000000000..e20d6ad9d
--- /dev/null
+++ b/drivers/acpi/fan.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * ACPI fan device IDs are shared between the fan driver and the device power
+ * management code.
+ *
+ * Add new device IDs before the generic ACPI fan one.
+ */
+
+#ifndef _ACPI_FAN_H_
+#define _ACPI_FAN_H_
+
+#include <linux/device.h>
+#include <linux/limits.h>
+#include <linux/types.h>
+
+#define ACPI_FAN_DEVICE_IDS						\
+	{ .id = "INT3404" },	/* Fan */				\
+	{ .id = "INTC1044" },	/* Fan for Tiger Lake generation */	\
+	{ .id = "INTC1048" },	/* Fan for Alder Lake generation */	\
+	{ .id = "INTC1063" },	/* Fan for Meteor Lake generation */	\
+	{ .id = "INTC106A" },	/* Fan for Lunar Lake generation */	\
+	{ .id = "INTC10A2" },	/* Fan for Raptor Lake generation */	\
+	{ .id = "INTC10D6" },	/* Fan for Panther Lake generation */	\
+	{ .id = "INTC10FE" },	/* Fan for Wildcat Lake generation */	\
+	{ .id = "INTC10F5" },	/* Fan for Nova Lake generation */	\
+	{ .id = "PNP0C0B" }	/* Generic ACPI fan */
+
+#define ACPI_FPS_NAME_LEN	20
+
+struct acpi_fan_fps {
+	u64 control;
+	u64 trip_point;
+	u64 speed;
+	u64 noise_level;
+	u64 power;
+	char name[ACPI_FPS_NAME_LEN];
+	struct device_attribute dev_attr;
+};
+
+struct acpi_fan_fif {
+	u8 revision;
+	u8 fine_grain_ctrl;
+	u8 step_size;
+	u8 low_speed_notification;
+};
+
+struct acpi_fan_fst {
+	u64 revision;
+	u64 control;
+	u64 speed;
+};
+
+struct acpi_fan {
+	acpi_handle handle;
+	bool acpi4;
+	bool has_fst;
+	struct acpi_fan_fif fif;
+	struct acpi_fan_fps *fps;
+	int fps_count;
+	/* A value of 0 means that trippoint-related functions are not supported */
+	u32 fan_trip_granularity;
+#if IS_REACHABLE(CONFIG_HWMON)
+	struct device *hdev;
+#endif
+	struct thermal_cooling_device *cdev;
+	struct device_attribute fst_speed;
+	struct device_attribute fine_grain_control;
+};
+
+/**
+ * acpi_fan_speed_valid - Check if fan speed value is valid
+ * @speed: Speed value returned by the ACPI firmware
+ *
+ * Check if the fan speed value returned by the ACPI firmware is valid. This function is
+ * necessary as ACPI firmware implementations can return 0xFFFFFFFF to signal that the
+ * ACPI fan does not support speed reporting. Additionally, some buggy ACPI firmware
+ * implementations return a value larger than the 32-bit integer value defined by
+ * the ACPI specification when using placeholder values. Such invalid values are also
+ * detected by this function.
+ *
+ * Returns: True if the fan speed value is valid, false otherwise.
+ */
+static inline bool acpi_fan_speed_valid(u64 speed)
+{
+	return speed < U32_MAX;
+}
+
+/**
+ * acpi_fan_power_valid - Check if fan power value is valid
+ * @power: Power value returned by the ACPI firmware
+ *
+ * Check if the fan power value returned by the ACPI firmware is valid.
+ * See acpi_fan_speed_valid() for details.
+ *
+ * Returns: True if the fan power value is valid, false otherwise.
+ */
+static inline bool acpi_fan_power_valid(u64 power)
+{
+	return power < U32_MAX;
+}
+
+int acpi_fan_get_fst(acpi_handle handle, struct acpi_fan_fst *fst);
+int acpi_fan_create_attributes(struct acpi_device *device);
+void acpi_fan_delete_attributes(struct acpi_device *device);
+
+#if IS_REACHABLE(CONFIG_HWMON)
+int devm_acpi_fan_create_hwmon(struct device *dev);
+void acpi_fan_notify_hwmon(struct device *dev);
+#else
+static inline int devm_acpi_fan_create_hwmon(struct device *dev) { return 0; };
+static inline void acpi_fan_notify_hwmon(struct device *dev) { };
+#endif
+
+#endif