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/mtd/chips/chipreg.c | 102 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 102 insertions(+) create mode 100644 drivers/mtd/chips/chipreg.c (limited to 'drivers/mtd/chips/chipreg.c') diff --git a/drivers/mtd/chips/chipreg.c b/drivers/mtd/chips/chipreg.c new file mode 100644 index 000000000..a05e10368 --- /dev/null +++ b/drivers/mtd/chips/chipreg.c @@ -0,0 +1,102 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Registration for chip drivers + * + */ + +#include +#include +#include +#include +#include +#include +#include + +static DEFINE_SPINLOCK(chip_drvs_lock); +static LIST_HEAD(chip_drvs_list); + +void register_mtd_chip_driver(struct mtd_chip_driver *drv) +{ + spin_lock(&chip_drvs_lock); + list_add(&drv->list, &chip_drvs_list); + spin_unlock(&chip_drvs_lock); +} + +void unregister_mtd_chip_driver(struct mtd_chip_driver *drv) +{ + spin_lock(&chip_drvs_lock); + list_del(&drv->list); + spin_unlock(&chip_drvs_lock); +} + +static struct mtd_chip_driver *get_mtd_chip_driver (const char *name) +{ + struct mtd_chip_driver *ret = NULL, *this; + + spin_lock(&chip_drvs_lock); + + list_for_each_entry(this, &chip_drvs_list, list) { + if (!strcmp(this->name, name)) { + ret = this; + break; + } + } + if (ret && !try_module_get(ret->module)) + ret = NULL; + + spin_unlock(&chip_drvs_lock); + + return ret; +} + + /* Hide all the horrid details, like some silly person taking + get_module_symbol() away from us, from the caller. */ + +struct mtd_info *do_map_probe(const char *name, struct map_info *map) +{ + struct mtd_chip_driver *drv; + struct mtd_info *ret; + + drv = get_mtd_chip_driver(name); + + if (!drv && !request_module("%s", name)) + drv = get_mtd_chip_driver(name); + + if (!drv) + return NULL; + + ret = drv->probe(map); + + /* We decrease the use count here. It may have been a + probe-only module, which is no longer required from this + point, having given us a handle on (and increased the use + count of) the actual driver code. + */ + module_put(drv->module); + + return ret; +} +/* + * Destroy an MTD device which was created for a map device. + * Make sure the MTD device is already unregistered before calling this + */ +void map_destroy(struct mtd_info *mtd) +{ + struct map_info *map = mtd->priv; + + if (map->fldrv->destroy) + map->fldrv->destroy(mtd); + + module_put(map->fldrv->module); + + kfree(mtd); +} + +EXPORT_SYMBOL(register_mtd_chip_driver); +EXPORT_SYMBOL(unregister_mtd_chip_driver); +EXPORT_SYMBOL(do_map_probe); +EXPORT_SYMBOL(map_destroy); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("David Woodhouse "); +MODULE_DESCRIPTION("Core routines for registering and invoking MTD chip drivers"); -- cgit v1.3.1