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/base/module.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 114 insertions(+) create mode 100644 drivers/base/module.c (limited to 'drivers/base/module.c') diff --git a/drivers/base/module.c b/drivers/base/module.c new file mode 100644 index 000000000..6789dca48 --- /dev/null +++ b/drivers/base/module.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * module.c - module sysfs fun for drivers + */ +#include +#include +#include +#include +#include +#include "base.h" + +static char *make_driver_name(const struct device_driver *drv) +{ + char *driver_name; + + driver_name = kasprintf(GFP_KERNEL, "%s:%s", drv->bus->name, drv->name); + if (!driver_name) + return NULL; + + return driver_name; +} + +static void module_create_drivers_dir(struct module_kobject *mk) +{ + static DEFINE_MUTEX(drivers_dir_mutex); + + mutex_lock(&drivers_dir_mutex); + if (mk && !mk->drivers_dir) + mk->drivers_dir = kobject_create_and_add("drivers", &mk->kobj); + mutex_unlock(&drivers_dir_mutex); +} + +int module_add_driver(struct module *mod, const struct device_driver *drv) +{ + char *driver_name; + struct module_kobject *mk = NULL; + int ret; + + if (!drv) + return 0; + + if (mod) + mk = &mod->mkobj; + else if (drv->mod_name) { + /* Lookup or create built-in module entry in /sys/module */ + mk = lookup_or_create_module_kobject(drv->mod_name); + if (mk) { + /* remember our module structure */ + drv->p->mkobj = mk; + /* lookup_or_create_module_kobject took a reference */ + kobject_put(&mk->kobj); + } + } + + if (!mk) + return 0; + + ret = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module"); + if (ret) + return ret; + + driver_name = make_driver_name(drv); + if (!driver_name) { + ret = -ENOMEM; + goto out_remove_kobj; + } + + module_create_drivers_dir(mk); + if (!mk->drivers_dir) { + ret = -EINVAL; + goto out_free_driver_name; + } + + ret = sysfs_create_link(mk->drivers_dir, &drv->p->kobj, driver_name); + if (ret) + goto out_remove_drivers_dir; + + kfree(driver_name); + + return 0; + +out_remove_drivers_dir: + sysfs_remove_link(mk->drivers_dir, driver_name); + +out_free_driver_name: + kfree(driver_name); + +out_remove_kobj: + sysfs_remove_link(&drv->p->kobj, "module"); + return ret; +} + +void module_remove_driver(const struct device_driver *drv) +{ + struct module_kobject *mk = NULL; + char *driver_name; + + if (!drv) + return; + + sysfs_remove_link(&drv->p->kobj, "module"); + + if (drv->owner) + mk = &drv->owner->mkobj; + else if (drv->p->mkobj) + mk = drv->p->mkobj; + if (mk && mk->drivers_dir) { + driver_name = make_driver_name(drv); + if (driver_name) { + sysfs_remove_link(mk->drivers_dir, driver_name); + kfree(driver_name); + } + } +} -- cgit v1.3.1