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/platform.c | 366 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 366 insertions(+) create mode 100644 lib/kunit/platform.c (limited to 'lib/kunit/platform.c') diff --git a/lib/kunit/platform.c b/lib/kunit/platform.c new file mode 100644 index 000000000..737758d71 --- /dev/null +++ b/lib/kunit/platform.c @@ -0,0 +1,366 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test managed platform driver + */ + +#include +#include +#include +#include +#include + +#include +#include + +struct kunit_platform_device_alloc_params { + const char *name; + int id; +}; + +static int kunit_platform_device_alloc_init(struct kunit_resource *res, void *context) +{ + struct kunit_platform_device_alloc_params *params = context; + struct platform_device *pdev; + + pdev = platform_device_alloc(params->name, params->id); + if (!pdev) + return -ENOMEM; + + res->data = pdev; + + return 0; +} + +static void kunit_platform_device_alloc_exit(struct kunit_resource *res) +{ + struct platform_device *pdev = res->data; + + platform_device_put(pdev); +} + +/** + * kunit_platform_device_alloc() - Allocate a KUnit test managed platform device + * @test: test context + * @name: device name of platform device to alloc + * @id: identifier of platform device to alloc. + * + * Allocate a test managed platform device. The device is put when the test completes. + * + * Return: Allocated platform device on success, NULL on failure. + */ +struct platform_device * +kunit_platform_device_alloc(struct kunit *test, const char *name, int id) +{ + struct kunit_platform_device_alloc_params params = { + .name = name, + .id = id, + }; + + return kunit_alloc_resource(test, + kunit_platform_device_alloc_init, + kunit_platform_device_alloc_exit, + GFP_KERNEL, ¶ms); +} +EXPORT_SYMBOL_GPL(kunit_platform_device_alloc); + +static void kunit_platform_device_add_exit(struct kunit_resource *res) +{ + struct platform_device *pdev = res->data; + + platform_device_unregister(pdev); +} + +static bool +kunit_platform_device_alloc_match(struct kunit *test, + struct kunit_resource *res, void *match_data) +{ + struct platform_device *pdev = match_data; + + return res->data == pdev && res->free == kunit_platform_device_alloc_exit; +} + +KUNIT_DEFINE_ACTION_WRAPPER(platform_device_unregister_wrapper, + platform_device_unregister, struct platform_device *); +/** + * kunit_platform_device_add() - Register a KUnit test managed platform device + * @test: test context + * @pdev: platform device to add + * + * Register a test managed platform device. The device is unregistered when the + * test completes. + * + * Return: 0 on success, negative errno on failure. + */ +int kunit_platform_device_add(struct kunit *test, struct platform_device *pdev) +{ + struct kunit_resource *res; + int ret; + + ret = platform_device_add(pdev); + if (ret) + return ret; + + res = kunit_find_resource(test, kunit_platform_device_alloc_match, pdev); + if (res) { + /* + * Transfer the reference count of the platform device if it + * was allocated with kunit_platform_device_alloc(). In this + * case, calling platform_device_put() when the test exits from + * kunit_platform_device_alloc_exit() would lead to reference + * count underflow because platform_device_unregister_wrapper() + * calls platform_device_unregister() which also calls + * platform_device_put(). + * + * Usually callers transfer the refcount initialized in + * platform_device_alloc() to platform_device_add() by calling + * platform_device_unregister() when platform_device_add() + * succeeds or platform_device_put() when it fails. KUnit has to + * keep this straight by redirecting the free routine for the + * resource to the right function. Luckily this only has to + * account for the success scenario. + */ + res->free = kunit_platform_device_add_exit; + kunit_put_resource(res); + } else { + ret = kunit_add_action_or_reset(test, platform_device_unregister_wrapper, pdev); + if (ret) + return ret; + } + + return 0; +} +EXPORT_SYMBOL_GPL(kunit_platform_device_add); + +/** + * kunit_platform_device_register_full() - Register a KUnit test-managed platform + * device described by platform device info + * @test: test context + * @pdevinfo: platform device information describing the new device + * + * Register a test-managed platform device. The device is unregistered when the + * test completes. + * + * Return: New platform device on success, IS_ERR() on error. + */ +struct platform_device * +kunit_platform_device_register_full(struct kunit *test, + const struct platform_device_info *pdevinfo) +{ + struct platform_device *pdev; + int ret; + + pdev = platform_device_register_full(pdevinfo); + if (IS_ERR(pdev)) + return pdev; + + ret = kunit_add_action_or_reset(test, platform_device_unregister_wrapper, pdev); + if (ret) + return ERR_PTR(ret); + + return pdev; +} +EXPORT_SYMBOL_GPL(kunit_platform_device_register_full); + +static bool +kunit_platform_device_add_match(struct kunit *test, struct kunit_resource *res, + void *match_data) +{ + struct platform_device *pdev = match_data; + + return res->data == pdev && res->free == kunit_platform_device_add_exit; +} + +/** + * kunit_platform_device_unregister() - Unregister a KUnit-managed platform device + * @test: test context + * @pdev: platform device to unregister + * + * Unregister a test-managed platform device and cancel its release action. + */ +void kunit_platform_device_unregister(struct kunit *test, + struct platform_device *pdev) +{ + struct kunit_resource *res; + + res = kunit_find_resource(test, kunit_platform_device_add_match, pdev); + if (res) { + res->free = NULL; + kunit_put_resource(res); + } else { + kunit_remove_action(test, platform_device_unregister_wrapper, pdev); + } + + platform_device_unregister(pdev); +} +EXPORT_SYMBOL_GPL(kunit_platform_device_unregister); + +struct kunit_platform_device_probe_nb { + struct completion *x; + struct device *dev; + struct notifier_block nb; +}; + +static int kunit_platform_device_probe_notify(struct notifier_block *nb, + unsigned long event, void *data) +{ + struct kunit_platform_device_probe_nb *knb; + struct device *dev = data; + + knb = container_of(nb, struct kunit_platform_device_probe_nb, nb); + if (event != BUS_NOTIFY_BOUND_DRIVER || knb->dev != dev) + return NOTIFY_DONE; + + complete(knb->x); + + return NOTIFY_OK; +} + +static void kunit_platform_device_probe_nb_remove(void *nb) +{ + bus_unregister_notifier(&platform_bus_type, nb); +} + +/** + * kunit_platform_device_prepare_wait_for_probe() - Prepare a completion + * variable to wait for a platform device to probe + * @test: test context + * @pdev: platform device to prepare to wait for probe of + * @x: completion variable completed when @dev has probed + * + * Prepare a completion variable @x to wait for @pdev to probe. Waiting on the + * completion forces a preemption, allowing the platform driver to probe. + * + * Example + * + * .. code-block:: c + * + * static int kunit_platform_driver_probe(struct platform_device *pdev) + * { + * return 0; + * } + * + * static void kunit_platform_driver_test(struct kunit *test) + * { + * struct platform_device *pdev; + * struct platform_driver *pdrv; + * DECLARE_COMPLETION_ONSTACK(comp); + * + * pdev = kunit_platform_device_alloc(test, "kunit-platform", -1); + * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdev); + * KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_add(test, pdev)); + * + * pdrv = kunit_kzalloc(test, sizeof(*pdrv), GFP_KERNEL); + * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, pdrv); + * + * pdrv->probe = kunit_platform_driver_probe; + * pdrv->driver.name = "kunit-platform"; + * pdrv->driver.owner = THIS_MODULE; + * + * KUNIT_ASSERT_EQ(test, 0, kunit_platform_device_prepare_wait_for_probe(test, pdev, &comp)); + * KUNIT_ASSERT_EQ(test, 0, kunit_platform_driver_register(test, pdrv)); + * + * KUNIT_EXPECT_NE(test, 0, wait_for_completion_timeout(&comp, 3 * HZ)); + * } + * + * Return: 0 on success, negative errno on failure. + */ +int kunit_platform_device_prepare_wait_for_probe(struct kunit *test, + struct platform_device *pdev, + struct completion *x) +{ + struct device *dev = &pdev->dev; + struct kunit_platform_device_probe_nb *knb; + bool bound; + + knb = kunit_kzalloc(test, sizeof(*knb), GFP_KERNEL); + if (!knb) + return -ENOMEM; + + knb->nb.notifier_call = kunit_platform_device_probe_notify; + knb->dev = dev; + knb->x = x; + + device_lock(dev); + bound = device_is_bound(dev); + if (bound) { + device_unlock(dev); + complete(x); + kunit_kfree(test, knb); + return 0; + } + + bus_register_notifier(&platform_bus_type, &knb->nb); + device_unlock(&pdev->dev); + + return kunit_add_action_or_reset(test, kunit_platform_device_probe_nb_remove, &knb->nb); +} +EXPORT_SYMBOL_GPL(kunit_platform_device_prepare_wait_for_probe); + +KUNIT_DEFINE_ACTION_WRAPPER(platform_driver_unregister_wrapper, + platform_driver_unregister, struct platform_driver *); +/** + * kunit_platform_driver_register() - Register a KUnit test managed platform driver + * @test: test context + * @drv: platform driver to register + * + * Register a test managed platform driver. This allows callers to embed the + * @drv in a container structure and use container_of() in the probe function + * to pass information to KUnit tests. + * + * Example + * + * .. code-block:: c + * + * struct kunit_test_context { + * struct platform_driver pdrv; + * const char *data; + * }; + * + * static inline struct kunit_test_context * + * to_test_context(struct platform_device *pdev) + * { + * return container_of(to_platform_driver(pdev->dev.driver), + * struct kunit_test_context, + * pdrv); + * } + * + * static int kunit_platform_driver_probe(struct platform_device *pdev) + * { + * struct kunit_test_context *ctx; + * + * ctx = to_test_context(pdev); + * ctx->data = "test data"; + * + * return 0; + * } + * + * static void kunit_platform_driver_test(struct kunit *test) + * { + * struct kunit_test_context *ctx; + * + * ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL); + * KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx); + * + * ctx->pdrv.probe = kunit_platform_driver_probe; + * ctx->pdrv.driver.name = "kunit-platform"; + * ctx->pdrv.driver.owner = THIS_MODULE; + * + * KUNIT_EXPECT_EQ(test, 0, kunit_platform_driver_register(test, &ctx->pdrv)); + * <... wait for driver to probe ...> + * KUNIT_EXPECT_STREQ(test, ctx->data, "test data"); + * } + * + * Return: 0 on success, negative errno on failure. + */ +int kunit_platform_driver_register(struct kunit *test, + struct platform_driver *drv) +{ + int ret; + + ret = platform_driver_register(drv); + if (ret) + return ret; + + return kunit_add_action_or_reset(test, platform_driver_unregister_wrapper, drv); +} +EXPORT_SYMBOL_GPL(kunit_platform_driver_register); -- cgit v1.3.1