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 --- net/ipv4/ipmr_base.c | 450 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 450 insertions(+) create mode 100644 net/ipv4/ipmr_base.c (limited to 'net/ipv4/ipmr_base.c') diff --git a/net/ipv4/ipmr_base.c b/net/ipv4/ipmr_base.c new file mode 100644 index 000000000..a0ec6d19a --- /dev/null +++ b/net/ipv4/ipmr_base.c @@ -0,0 +1,450 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Linux multicast routing support + * Common logic shared by IPv4 [ipmr] and IPv6 [ip6mr] implementation + */ + +#include +#include + +/* Sets everything common except 'dev', since that is done under locking */ +void vif_device_init(struct vif_device *v, + struct net_device *dev, + unsigned long rate_limit, + unsigned char threshold, + unsigned short flags, + unsigned short get_iflink_mask) +{ + RCU_INIT_POINTER(v->dev, NULL); + v->bytes_in = 0; + v->bytes_out = 0; + v->pkt_in = 0; + v->pkt_out = 0; + v->rate_limit = rate_limit; + v->flags = flags; + v->threshold = threshold; + if (v->flags & get_iflink_mask) + v->link = dev_get_iflink(dev); + else + v->link = dev->ifindex; +} + +static void __mr_free_table(struct work_struct *work) +{ + struct mr_table *mrt = container_of(to_rcu_work(work), + struct mr_table, work); + + rhltable_destroy(&mrt->mfc_hash); + kfree(mrt); +} + +void mr_table_free(struct mr_table *mrt) +{ + queue_rcu_work(system_dfl_wq, &mrt->work); +} + +struct mr_table * +mr_table_alloc(struct net *net, u32 id, + struct mr_table_ops *ops, + void (*expire_func)(struct timer_list *t), + void (*table_set)(struct mr_table *mrt, + struct net *net)) +{ + struct mr_table *mrt; + int err; + + mrt = kzalloc_obj(*mrt, GFP_KERNEL_ACCOUNT); + if (!mrt) + return ERR_PTR(-ENOMEM); + mrt->id = id; + write_pnet(&mrt->net, net); + + mrt->ops = *ops; + err = rhltable_init(&mrt->mfc_hash, mrt->ops.rht_params); + if (err) { + kfree(mrt); + return ERR_PTR(err); + } + + INIT_RCU_WORK(&mrt->work, __mr_free_table); + INIT_LIST_HEAD(&mrt->mfc_cache_list); + INIT_LIST_HEAD(&mrt->mfc_unres_queue); + + timer_setup(&mrt->ipmr_expire_timer, expire_func, 0); + + mrt->mroute_reg_vif_num = -1; + table_set(mrt, net); + return mrt; +} + +void *mr_mfc_find_parent(struct mr_table *mrt, void *hasharg, int parent) +{ + struct rhlist_head *tmp, *list; + struct mr_mfc *c; + + list = rhltable_lookup(&mrt->mfc_hash, hasharg, *mrt->ops.rht_params); + rhl_for_each_entry_rcu(c, tmp, list, mnode) + if (parent == -1 || parent == c->mfc_parent) + return c; + + return NULL; +} + +void *mr_mfc_find_any_parent(struct mr_table *mrt, int vifi) +{ + struct rhlist_head *tmp, *list; + struct mr_mfc *c; + + list = rhltable_lookup(&mrt->mfc_hash, mrt->ops.cmparg_any, + *mrt->ops.rht_params); + rhl_for_each_entry_rcu(c, tmp, list, mnode) + if (c->mfc_un.res.ttls[vifi] < 255) + return c; + + return NULL; +} + +void *mr_mfc_find_any(struct mr_table *mrt, int vifi, void *hasharg) +{ + struct rhlist_head *tmp, *list; + struct mr_mfc *c, *proxy; + + list = rhltable_lookup(&mrt->mfc_hash, hasharg, *mrt->ops.rht_params); + rhl_for_each_entry_rcu(c, tmp, list, mnode) { + if (c->mfc_un.res.ttls[vifi] < 255) + return c; + + /* It's ok if the vifi is part of the static tree */ + proxy = mr_mfc_find_any_parent(mrt, c->mfc_parent); + if (proxy && proxy->mfc_un.res.ttls[vifi] < 255) + return c; + } + + return mr_mfc_find_any_parent(mrt, vifi); +} + +#ifdef CONFIG_PROC_FS +void *mr_vif_seq_idx(struct net *net, struct mr_vif_iter *iter, loff_t pos) +{ + struct mr_table *mrt = iter->mrt; + + for (iter->ct = 0; iter->ct < mrt->maxvif; ++iter->ct) { + if (!VIF_EXISTS(mrt, iter->ct)) + continue; + if (pos-- == 0) + return &mrt->vif_table[iter->ct]; + } + return NULL; +} + +void *mr_vif_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct mr_vif_iter *iter = seq->private; + struct net *net = seq_file_net(seq); + struct mr_table *mrt = iter->mrt; + + ++*pos; + if (v == SEQ_START_TOKEN) + return mr_vif_seq_idx(net, iter, 0); + + while (++iter->ct < mrt->maxvif) { + if (!VIF_EXISTS(mrt, iter->ct)) + continue; + return &mrt->vif_table[iter->ct]; + } + return NULL; +} + +void *mr_mfc_seq_idx(struct net *net, + struct mr_mfc_iter *it, loff_t pos) +{ + struct mr_table *mrt = it->mrt; + struct mr_mfc *mfc; + + rcu_read_lock(); + it->cache = &mrt->mfc_cache_list; + list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) + if (pos-- == 0) + return mfc; + rcu_read_unlock(); + + spin_lock_bh(it->lock); + it->cache = &mrt->mfc_unres_queue; + list_for_each_entry(mfc, it->cache, list) + if (pos-- == 0) + return mfc; + spin_unlock_bh(it->lock); + + it->cache = NULL; + return NULL; +} + +void *mr_mfc_seq_next(struct seq_file *seq, void *v, + loff_t *pos) +{ + struct mr_mfc_iter *it = seq->private; + struct net *net = seq_file_net(seq); + struct mr_table *mrt = it->mrt; + struct mr_mfc *c = v; + + ++*pos; + + if (v == SEQ_START_TOKEN) + return mr_mfc_seq_idx(net, seq->private, 0); + + if (c->list.next != it->cache) + return list_entry(c->list.next, struct mr_mfc, list); + + if (it->cache == &mrt->mfc_unres_queue) + goto end_of_list; + + /* exhausted cache_array, show unresolved */ + rcu_read_unlock(); + it->cache = &mrt->mfc_unres_queue; + + spin_lock_bh(it->lock); + if (!list_empty(it->cache)) + return list_first_entry(it->cache, struct mr_mfc, list); + +end_of_list: + spin_unlock_bh(it->lock); + it->cache = NULL; + + return NULL; +} +#endif + +int mr_fill_mroute(struct mr_table *mrt, struct sk_buff *skb, + struct mr_mfc *c, struct rtmsg *rtm) +{ + struct net_device *vif_dev; + struct rta_mfc_stats mfcs; + struct nlattr *mp_attr; + struct rtnexthop *nhp; + unsigned long lastuse; + int ct; + + /* If cache is unresolved, don't try to parse IIF and OIF */ + if (c->mfc_parent >= MAXVIFS) { + rtm->rtm_flags |= RTNH_F_UNRESOLVED; + return -ENOENT; + } + + rcu_read_lock(); + vif_dev = rcu_dereference(mrt->vif_table[c->mfc_parent].dev); + if (vif_dev && nla_put_u32(skb, RTA_IIF, READ_ONCE(vif_dev->ifindex)) < 0) { + rcu_read_unlock(); + return -EMSGSIZE; + } + rcu_read_unlock(); + + if (c->mfc_flags & MFC_OFFLOAD) + rtm->rtm_flags |= RTNH_F_OFFLOAD; + + mp_attr = nla_nest_start_noflag(skb, RTA_MULTIPATH); + if (!mp_attr) + return -EMSGSIZE; + + rcu_read_lock(); + for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) { + struct vif_device *vif = &mrt->vif_table[ct]; + + vif_dev = rcu_dereference(vif->dev); + if (vif_dev && c->mfc_un.res.ttls[ct] < 255) { + + nhp = nla_reserve_nohdr(skb, sizeof(*nhp)); + if (!nhp) { + rcu_read_unlock(); + nla_nest_cancel(skb, mp_attr); + return -EMSGSIZE; + } + + nhp->rtnh_flags = 0; + nhp->rtnh_hops = c->mfc_un.res.ttls[ct]; + nhp->rtnh_ifindex = READ_ONCE(vif_dev->ifindex); + nhp->rtnh_len = sizeof(*nhp); + } + } + rcu_read_unlock(); + + nla_nest_end(skb, mp_attr); + + lastuse = READ_ONCE(c->mfc_un.res.lastuse); + lastuse = time_after_eq(jiffies, lastuse) ? jiffies - lastuse : 0; + + mfcs.mfcs_packets = atomic_long_read(&c->mfc_un.res.pkt); + mfcs.mfcs_bytes = atomic_long_read(&c->mfc_un.res.bytes); + mfcs.mfcs_wrong_if = atomic_long_read(&c->mfc_un.res.wrong_if); + if (nla_put_64bit(skb, RTA_MFC_STATS, sizeof(mfcs), &mfcs, RTA_PAD) || + nla_put_u64_64bit(skb, RTA_EXPIRES, jiffies_to_clock_t(lastuse), + RTA_PAD)) + return -EMSGSIZE; + + rtm->rtm_type = RTN_MULTICAST; + return 1; +} + +static bool mr_mfc_uses_dev(const struct mr_table *mrt, + const struct mr_mfc *c, + const struct net_device *dev) +{ + int ct; + + for (ct = c->mfc_un.res.minvif; ct < c->mfc_un.res.maxvif; ct++) { + const struct net_device *vif_dev; + const struct vif_device *vif; + + vif = &mrt->vif_table[ct]; + vif_dev = rcu_access_pointer(vif->dev); + if (vif_dev && c->mfc_un.res.ttls[ct] < 255 && + vif_dev == dev) + return true; + } + return false; +} + +int mr_table_dump(struct mr_table *mrt, struct sk_buff *skb, + struct netlink_callback *cb, + int (*fill)(struct mr_table *mrt, struct sk_buff *skb, + u32 portid, u32 seq, struct mr_mfc *c, + int cmd, int flags), + spinlock_t *lock, struct fib_dump_filter *filter) +{ + unsigned int e = 0, s_e = cb->args[1]; + unsigned int flags = NLM_F_MULTI; + struct mr_mfc *mfc; + int err; + + if (filter->filter_set) + flags |= NLM_F_DUMP_FILTERED; + + list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list, + lockdep_rtnl_is_held()) { + if (e < s_e) + goto next_entry; + if (filter->dev && + !mr_mfc_uses_dev(mrt, mfc, filter->dev)) + goto next_entry; + + err = fill(mrt, skb, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, mfc, RTM_NEWROUTE, flags); + if (err < 0) + goto out; +next_entry: + e++; + } + + spin_lock_bh(lock); + list_for_each_entry(mfc, &mrt->mfc_unres_queue, list) { + if (e < s_e) + goto next_entry2; + + err = fill(mrt, skb, NETLINK_CB(cb->skb).portid, + cb->nlh->nlmsg_seq, mfc, RTM_NEWROUTE, flags); + if (err < 0) { + spin_unlock_bh(lock); + goto out; + } +next_entry2: + e++; + } + spin_unlock_bh(lock); + err = 0; +out: + cb->args[1] = e; + return err; +} + +int mr_rtm_dumproute(struct sk_buff *skb, struct netlink_callback *cb, + struct mr_table *(*iter)(struct net *net, + struct mr_table *mrt), + int (*fill)(struct mr_table *mrt, + struct sk_buff *skb, + u32 portid, u32 seq, struct mr_mfc *c, + int cmd, int flags), + spinlock_t *lock, struct fib_dump_filter *filter) +{ + unsigned int t = 0, s_t = cb->args[0]; + struct net *net = sock_net(skb->sk); + struct mr_table *mrt; + int err; + + /* multicast does not track protocol or have route type other + * than RTN_MULTICAST + */ + if (filter->filter_set) { + if (filter->protocol || filter->flags || + (filter->rt_type && filter->rt_type != RTN_MULTICAST)) + return skb->len; + } + + rcu_read_lock(); + for (mrt = iter(net, NULL); mrt; mrt = iter(net, mrt)) { + if (t < s_t) + goto next_table; + + err = mr_table_dump(mrt, skb, cb, fill, lock, filter); + if (err < 0) + break; + cb->args[1] = 0; +next_table: + t++; + } + rcu_read_unlock(); + + cb->args[0] = t; + + return skb->len; +} + +int mr_dump(struct net *net, struct notifier_block *nb, unsigned short family, + int (*rules_dump)(struct net *net, + struct notifier_block *nb, + struct netlink_ext_ack *extack), + struct mr_table *(*mr_iter)(struct net *net, + struct mr_table *mrt), + struct netlink_ext_ack *extack) +{ + struct mr_table *mrt; + int err; + + err = rules_dump(net, nb, extack); + if (err) + return err; + + for (mrt = mr_iter(net, NULL); mrt; mrt = mr_iter(net, mrt)) { + struct vif_device *v = &mrt->vif_table[0]; + struct net_device *vif_dev; + struct mr_mfc *mfc; + int vifi; + + /* Notifiy on table VIF entries */ + rcu_read_lock(); + for (vifi = 0; vifi < mrt->maxvif; vifi++, v++) { + vif_dev = rcu_dereference(v->dev); + if (!vif_dev) + continue; + + err = mr_call_vif_notifier(nb, family, + FIB_EVENT_VIF_ADD, v, + vif_dev, vifi, + mrt->id, extack); + if (err) + break; + } + rcu_read_unlock(); + + if (err) + return err; + + /* Notify on table MFC entries */ + list_for_each_entry_rcu(mfc, &mrt->mfc_cache_list, list) { + err = mr_call_mfc_notifier(nb, family, + FIB_EVENT_ENTRY_ADD, + mfc, mrt->id, extack); + if (err) + return err; + } + } + + return 0; +} -- cgit v1.3.1