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 --- drivers/nvmem/layouts.c | 205 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 205 insertions(+) create mode 100644 drivers/nvmem/layouts.c (limited to 'drivers/nvmem/layouts.c') diff --git a/drivers/nvmem/layouts.c b/drivers/nvmem/layouts.c new file mode 100644 index 000000000..07a34be96 --- /dev/null +++ b/drivers/nvmem/layouts.c @@ -0,0 +1,205 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * NVMEM layout bus handling + * + * Copyright (C) 2023 Bootlin + * Author: Miquel Raynal +#include +#include +#include +#include +#include +#include + +#include "internals.h" + +#define to_nvmem_layout_driver(drv) \ + (container_of_const((drv), struct nvmem_layout_driver, driver)) +#define to_nvmem_layout_device(_dev) \ + container_of((_dev), struct nvmem_layout, dev) + +static int nvmem_layout_bus_match(struct device *dev, const struct device_driver *drv) +{ + return of_driver_match_device(dev, drv); +} + +static int nvmem_layout_bus_probe(struct device *dev) +{ + struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver); + struct nvmem_layout *layout = to_nvmem_layout_device(dev); + + if (!drv->probe || !drv->remove) + return -EINVAL; + + return drv->probe(layout); +} + +static void nvmem_layout_bus_remove(struct device *dev) +{ + struct nvmem_layout_driver *drv = to_nvmem_layout_driver(dev->driver); + struct nvmem_layout *layout = to_nvmem_layout_device(dev); + + return drv->remove(layout); +} + +static int nvmem_layout_bus_uevent(const struct device *dev, + struct kobj_uevent_env *env) +{ + int ret; + + ret = of_device_uevent_modalias(dev, env); + if (ret != -ENODEV) + return ret; + + return 0; +} + +static const struct bus_type nvmem_layout_bus_type = { + .name = "nvmem-layout", + .match = nvmem_layout_bus_match, + .probe = nvmem_layout_bus_probe, + .remove = nvmem_layout_bus_remove, + .uevent = nvmem_layout_bus_uevent, +}; + +int __nvmem_layout_driver_register(struct nvmem_layout_driver *drv, + struct module *owner) +{ + drv->driver.bus = &nvmem_layout_bus_type; + drv->driver.owner = owner; + + return driver_register(&drv->driver); +} +EXPORT_SYMBOL_GPL(__nvmem_layout_driver_register); + +void nvmem_layout_driver_unregister(struct nvmem_layout_driver *drv) +{ + driver_unregister(&drv->driver); +} +EXPORT_SYMBOL_GPL(nvmem_layout_driver_unregister); + +static void nvmem_layout_release_device(struct device *dev) +{ + struct nvmem_layout *layout = to_nvmem_layout_device(dev); + + of_node_put(layout->dev.of_node); + kfree(layout); +} + +static int nvmem_layout_create_device(struct nvmem_device *nvmem, + struct device_node *np) +{ + struct nvmem_layout *layout; + struct device *dev; + int ret; + + layout = kzalloc_obj(*layout); + if (!layout) + return -ENOMEM; + + /* Create a bidirectional link */ + layout->nvmem = nvmem; + nvmem->layout = layout; + + /* Device model registration */ + dev = &layout->dev; + device_initialize(dev); + dev->parent = &nvmem->dev; + dev->bus = &nvmem_layout_bus_type; + dev->release = nvmem_layout_release_device; + dev->coherent_dma_mask = DMA_BIT_MASK(32); + dev->dma_mask = &dev->coherent_dma_mask; + device_set_node(dev, of_fwnode_handle(of_node_get(np))); + of_device_make_bus_id(dev); + of_msi_configure(dev, dev->of_node); + + ret = device_add(dev); + if (ret) { + put_device(dev); + return ret; + } + + return 0; +} + +static int nvmem_layout_bus_populate(struct nvmem_device *nvmem, + struct device_node *layout_dn) +{ + int ret; + + /* Make sure it has a compatible property */ + if (!of_property_present(layout_dn, "compatible")) { + pr_debug("%s() - skipping %pOF, no compatible prop\n", + __func__, layout_dn); + return 0; + } + + if (of_node_check_flag(layout_dn, OF_POPULATED_BUS)) { + pr_debug("%s() - skipping %pOF, already populated\n", + __func__, layout_dn); + + return 0; + } + + /* NVMEM layout buses expect only a single device representing the layout */ + ret = nvmem_layout_create_device(nvmem, layout_dn); + if (ret) + return ret; + + of_node_set_flag(layout_dn, OF_POPULATED_BUS); + + return 0; +} + +struct device_node *of_nvmem_layout_get_container(struct nvmem_device *nvmem) +{ + return of_get_child_by_name(nvmem->dev.of_node, "nvmem-layout"); +} +EXPORT_SYMBOL_GPL(of_nvmem_layout_get_container); + +/* + * Returns the number of devices populated, 0 if the operation was not relevant + * for this nvmem device, an error code otherwise. + */ +int nvmem_populate_layout(struct nvmem_device *nvmem) +{ + struct device_node *layout_dn; + int ret; + + layout_dn = of_nvmem_layout_get_container(nvmem); + if (!layout_dn) + return 0; + + /* Populate the layout device */ + device_links_supplier_sync_state_pause(); + ret = nvmem_layout_bus_populate(nvmem, layout_dn); + device_links_supplier_sync_state_resume(); + + of_node_put(layout_dn); + return ret; +} + +void nvmem_destroy_layout(struct nvmem_device *nvmem) +{ + struct device *dev; + + if (!nvmem->layout) + return; + + dev = &nvmem->layout->dev; + of_node_clear_flag(dev->of_node, OF_POPULATED_BUS); + device_unregister(dev); +} + +int nvmem_layout_bus_register(void) +{ + return bus_register(&nvmem_layout_bus_type); +} + +void nvmem_layout_bus_unregister(void) +{ + bus_unregister(&nvmem_layout_bus_type); +} -- cgit v1.3.1