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/tcp_ulp.c | 168 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 168 insertions(+) create mode 100644 net/ipv4/tcp_ulp.c (limited to 'net/ipv4/tcp_ulp.c') diff --git a/net/ipv4/tcp_ulp.c b/net/ipv4/tcp_ulp.c new file mode 100644 index 000000000..2aa442128 --- /dev/null +++ b/net/ipv4/tcp_ulp.c @@ -0,0 +1,168 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Pluggable TCP upper layer protocol support. + * + * Copyright (c) 2016-2017, Mellanox Technologies. All rights reserved. + * Copyright (c) 2016-2017, Dave Watson . All rights reserved. + * + */ + +#include +#include +#include +#include +#include +#include + +static DEFINE_SPINLOCK(tcp_ulp_list_lock); +static LIST_HEAD(tcp_ulp_list); + +/* Simple linear search, don't expect many entries! */ +static struct tcp_ulp_ops *tcp_ulp_find(const char *name) +{ + struct tcp_ulp_ops *e; + + list_for_each_entry_rcu(e, &tcp_ulp_list, list, + lockdep_is_held(&tcp_ulp_list_lock)) { + if (strcmp(e->name, name) == 0) + return e; + } + + return NULL; +} + +static const struct tcp_ulp_ops *__tcp_ulp_find_autoload(const char *name) +{ + const struct tcp_ulp_ops *ulp = NULL; + + rcu_read_lock(); + ulp = tcp_ulp_find(name); + +#ifdef CONFIG_MODULES + if (!ulp && capable(CAP_NET_ADMIN)) { + rcu_read_unlock(); + request_module("tcp-ulp-%s", name); + rcu_read_lock(); + ulp = tcp_ulp_find(name); + } +#endif + if (!ulp || !try_module_get(ulp->owner)) + ulp = NULL; + + rcu_read_unlock(); + return ulp; +} + +/* Attach new upper layer protocol to the list + * of available protocols. + */ +int tcp_register_ulp(struct tcp_ulp_ops *ulp) +{ + int ret = 0; + + spin_lock(&tcp_ulp_list_lock); + if (tcp_ulp_find(ulp->name)) + ret = -EEXIST; + else + list_add_tail_rcu(&ulp->list, &tcp_ulp_list); + spin_unlock(&tcp_ulp_list_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(tcp_register_ulp); + +void tcp_unregister_ulp(struct tcp_ulp_ops *ulp) +{ + spin_lock(&tcp_ulp_list_lock); + list_del_rcu(&ulp->list); + spin_unlock(&tcp_ulp_list_lock); + + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(tcp_unregister_ulp); + +/* Build string with list of available upper layer protocl values */ +void tcp_get_available_ulp(char *buf, size_t maxlen) +{ + struct tcp_ulp_ops *ulp_ops; + size_t offs = 0; + + *buf = '\0'; + rcu_read_lock(); + list_for_each_entry_rcu(ulp_ops, &tcp_ulp_list, list) { + offs += snprintf(buf + offs, maxlen - offs, + "%s%s", + offs == 0 ? "" : " ", ulp_ops->name); + + if (WARN_ON_ONCE(offs >= maxlen)) + break; + } + rcu_read_unlock(); +} + +void tcp_update_ulp(struct sock *sk, struct proto *proto, + void (*write_space)(struct sock *sk)) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ulp_ops->update) + icsk->icsk_ulp_ops->update(sk, proto, write_space); +} + +void tcp_cleanup_ulp(struct sock *sk) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + + /* No sock_owned_by_me() check here as at the time the + * stack calls this function, the socket is dead and + * about to be destroyed. + */ + if (!icsk->icsk_ulp_ops) + return; + + if (icsk->icsk_ulp_ops->release) + icsk->icsk_ulp_ops->release(sk); + module_put(icsk->icsk_ulp_ops->owner); + + icsk->icsk_ulp_ops = NULL; +} + +static int __tcp_set_ulp(struct sock *sk, const struct tcp_ulp_ops *ulp_ops) +{ + struct inet_connection_sock *icsk = inet_csk(sk); + int err; + + err = -EEXIST; + if (icsk->icsk_ulp_ops) + goto out_err; + + if (sk->sk_socket) + clear_bit(SOCK_SUPPORT_ZC, &sk->sk_socket->flags); + + err = -ENOTCONN; + if (!ulp_ops->clone && sk->sk_state == TCP_LISTEN) + goto out_err; + + err = ulp_ops->init(sk); + if (err) + goto out_err; + + icsk->icsk_ulp_ops = ulp_ops; + return 0; +out_err: + module_put(ulp_ops->owner); + return err; +} + +int tcp_set_ulp(struct sock *sk, const char *name) +{ + const struct tcp_ulp_ops *ulp_ops; + + sock_owned_by_me(sk); + + ulp_ops = __tcp_ulp_find_autoload(name); + if (!ulp_ops) + return -ENOENT; + + return __tcp_set_ulp(sk, ulp_ops); +} -- cgit v1.3.1