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/dma/idxd/compat.c | 121 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 drivers/dma/idxd/compat.c (limited to 'drivers/dma/idxd/compat.c') diff --git a/drivers/dma/idxd/compat.c b/drivers/dma/idxd/compat.c new file mode 100644 index 000000000..95b8ef958 --- /dev/null +++ b/drivers/dma/idxd/compat.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright(c) 2021 Intel Corporation. All rights rsvd. */ +#include +#include +#include +#include +#include +#include "idxd.h" + +extern void device_driver_detach(struct device *dev); + +#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ + struct driver_attribute driver_attr_##_name = \ + __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) + +static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count) +{ + const struct bus_type *bus = drv->bus; + struct device *dev; + int rc = -ENODEV; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (!dev) + return -ENODEV; + + if (dev->driver) { + device_driver_detach(dev); + rc = count; + } + + put_device(dev); + + return rc; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store); + +static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count) +{ + const struct bus_type *bus = drv->bus; + struct device *dev; + struct device_driver *alt_drv = NULL; + int rc = -ENODEV; + struct idxd_dev *idxd_dev; + + dev = bus_find_device_by_name(bus, NULL, buf); + if (!dev) + return -ENODEV; + + if (dev->driver || drv != &dsa_drv.drv) + goto err_put_dev; + + idxd_dev = confdev_to_idxd_dev(dev); + if (is_idxd_dev(idxd_dev)) { + alt_drv = driver_find("idxd", bus); + } else if (is_idxd_wq_dev(idxd_dev)) { + struct idxd_wq *wq = confdev_to_wq(dev); + + if (is_idxd_wq_kernel(wq)) + alt_drv = driver_find("dmaengine", bus); + else if (is_idxd_wq_user(wq)) + alt_drv = driver_find("user", bus); + } + if (!alt_drv) + goto err_put_dev; + + rc = device_driver_attach(alt_drv, dev); + if (rc < 0) + goto err_put_dev; + + put_device(dev); + + return count; + +err_put_dev: + put_device(dev); + + return rc; +} +static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store); + +static struct attribute *dsa_drv_compat_attrs[] = { + &driver_attr_bind.attr, + &driver_attr_unbind.attr, + NULL, +}; + +static const struct attribute_group dsa_drv_compat_attr_group = { + .attrs = dsa_drv_compat_attrs, +}; + +static const struct attribute_group *dsa_drv_compat_groups[] = { + &dsa_drv_compat_attr_group, + NULL, +}; + +static int idxd_dsa_drv_probe(struct idxd_dev *idxd_dev) +{ + return -ENODEV; +} + +static void idxd_dsa_drv_remove(struct idxd_dev *idxd_dev) +{ +} + +static enum idxd_dev_type dev_types[] = { + IDXD_DEV_NONE, +}; + +struct idxd_device_driver dsa_drv = { + .name = "dsa", + .probe = idxd_dsa_drv_probe, + .remove = idxd_dsa_drv_remove, + .type = dev_types, + .drv = { + .suppress_bind_attrs = true, + .groups = dsa_drv_compat_groups, + }, +}; + +module_idxd_driver(dsa_drv); +MODULE_IMPORT_NS("IDXD"); -- cgit v1.3.1