From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- lib/kunit/device.c | 201 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 201 insertions(+) create mode 100644 lib/kunit/device.c (limited to 'lib/kunit/device.c') diff --git a/lib/kunit/device.c b/lib/kunit/device.c new file mode 100644 index 000000000..85d57ad34 --- /dev/null +++ b/lib/kunit/device.c @@ -0,0 +1,201 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * KUnit-managed device implementation + * + * Implementation of struct kunit_device helpers for fake devices whose + * lifecycle is managed by KUnit. + * + * Copyright (C) 2023, Google LLC. + * Author: David Gow + */ + +#include +#include + +#include +#include +#include + +#include "device-impl.h" + +/* Wrappers for use with kunit_add_action() */ +KUNIT_DEFINE_ACTION_WRAPPER(device_unregister_wrapper, device_unregister, struct device *); +KUNIT_DEFINE_ACTION_WRAPPER(driver_unregister_wrapper, driver_unregister, struct device_driver *); + +/* The root device for the KUnit bus, parent of all kunit_devices. */ +static struct device *kunit_bus_device; + +/* A device owned by a KUnit test. */ +struct kunit_device { + struct device dev; + /* The KUnit test which owns this device. */ + struct kunit *owner; + /* If the driver is managed by KUnit and unique to this device. */ + const struct device_driver *driver; +}; + +#define to_kunit_device(d) container_of_const(d, struct kunit_device, dev) + +static const struct bus_type kunit_bus_type = { + .name = "kunit", +}; + +/* Register the 'kunit_bus' used for fake devices. */ +int kunit_bus_init(void) +{ + int error; + + kunit_bus_device = root_device_register("kunit"); + if (IS_ERR(kunit_bus_device)) + return PTR_ERR(kunit_bus_device); + + error = bus_register(&kunit_bus_type); + if (error) + root_device_unregister(kunit_bus_device); + return error; +} + +/* Unregister the 'kunit_bus' in case the KUnit module is unloaded. */ +void kunit_bus_shutdown(void) +{ + /* Make sure the bus exists before we unregister it. */ + if (IS_ERR_OR_NULL(kunit_bus_device)) + return; + + bus_unregister(&kunit_bus_type); + + root_device_unregister(kunit_bus_device); + + kunit_bus_device = NULL; +} + +/* Release a 'fake' KUnit device. */ +static void kunit_device_release(struct device *d) +{ + kfree(to_kunit_device(d)); +} + +/* + * Create and register a KUnit-managed struct device_driver on the kunit_bus. + * Returns an error pointer on failure. + */ +struct device_driver *kunit_driver_create(struct kunit *test, const char *name) +{ + struct device_driver *driver; + int err = -ENOMEM; + + driver = kunit_kzalloc(test, sizeof(*driver), GFP_KERNEL); + + if (!driver) + return ERR_PTR(err); + + driver->name = kunit_kstrdup_const(test, name, GFP_KERNEL); + driver->bus = &kunit_bus_type; + driver->owner = THIS_MODULE; + + err = driver_register(driver); + if (err) { + kunit_kfree(test, driver); + return ERR_PTR(err); + } + + kunit_add_action(test, driver_unregister_wrapper, driver); + return driver; +} +EXPORT_SYMBOL_GPL(kunit_driver_create); + +/* Helper which creates a kunit_device, attaches it to the kunit_bus*/ +static struct kunit_device *kunit_device_register_internal(struct kunit *test, + const char *name) +{ + struct kunit_device *kunit_dev; + int err = -ENOMEM; + + kunit_dev = kzalloc_obj(*kunit_dev); + if (!kunit_dev) + return ERR_PTR(err); + + kunit_dev->owner = test; + + err = dev_set_name(&kunit_dev->dev, "%s.%s", test->name, name); + if (err) { + kfree(kunit_dev); + return ERR_PTR(err); + } + + kunit_dev->dev.release = kunit_device_release; + kunit_dev->dev.bus = &kunit_bus_type; + kunit_dev->dev.parent = kunit_bus_device; + + err = device_register(&kunit_dev->dev); + if (err) { + put_device(&kunit_dev->dev); + return ERR_PTR(err); + } + + kunit_dev->dev.dma_mask = &kunit_dev->dev.coherent_dma_mask; + kunit_dev->dev.coherent_dma_mask = DMA_BIT_MASK(32); + + kunit_add_action(test, device_unregister_wrapper, &kunit_dev->dev); + + return kunit_dev; +} + +/* + * Create and register a new KUnit-managed device, using the user-supplied device_driver. + * On failure, returns an error pointer. + */ +struct device *kunit_device_register_with_driver(struct kunit *test, + const char *name, + const struct device_driver *drv) +{ + struct kunit_device *kunit_dev = kunit_device_register_internal(test, name); + + if (IS_ERR_OR_NULL(kunit_dev)) + return ERR_CAST(kunit_dev); + + return &kunit_dev->dev; +} +EXPORT_SYMBOL_GPL(kunit_device_register_with_driver); + +/* + * Create and register a new KUnit-managed device, including a matching device_driver. + * On failure, returns an error pointer. + */ +struct device *kunit_device_register(struct kunit *test, const char *name) +{ + struct device_driver *drv; + struct kunit_device *dev; + + drv = kunit_driver_create(test, name); + if (IS_ERR(drv)) + return ERR_CAST(drv); + + dev = kunit_device_register_internal(test, name); + if (IS_ERR(dev)) { + kunit_release_action(test, driver_unregister_wrapper, (void *)drv); + return ERR_CAST(dev); + } + + /* Request the driver be freed. */ + dev->driver = drv; + + + return &dev->dev; +} +EXPORT_SYMBOL_GPL(kunit_device_register); + +/* Unregisters a KUnit-managed device early (including the driver, if automatically created). */ +void kunit_device_unregister(struct kunit *test, struct device *dev) +{ + const struct device_driver *driver = to_kunit_device(dev)->driver; + + kunit_release_action(test, device_unregister_wrapper, dev); + if (driver) { + const char *driver_name = driver->name; + kunit_release_action(test, driver_unregister_wrapper, (void *)driver); + kunit_kfree_const(test, driver_name); + } +} +EXPORT_SYMBOL_GPL(kunit_device_unregister); + -- cgit v1.3.1