KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 227 insertions, 0 deletions

diff --git a/net/bluetooth/bnep/netdev.c b/net/bluetooth/bnep/netdev.c
new file mode 100644
index 000000000..ee1e39a3d
--- /dev/null
+++ b/net/bluetooth/bnep/netdev.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+   BNEP implementation for Linux Bluetooth stack (BlueZ).
+   Copyright (C) 2001-2002 Inventel Systemes
+   Written 2001-2002 by
+	Clément Moreau <clement.moreau@inventel.fr>
+	David Libault  <david.libault@inventel.fr>
+
+   Copyright (C) 2002 Maxim Krasnyansky <maxk@qualcomm.com>
+
+   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
+   IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
+   CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
+   WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+   ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+   OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+   ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
+   COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
+   SOFTWARE IS DISCLAIMED.
+*/
+
+#include <linux/etherdevice.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+#include <net/bluetooth/l2cap.h>
+
+#include "bnep.h"
+
+#define BNEP_TX_QUEUE_LEN 20
+
+static int bnep_net_open(struct net_device *dev)
+{
+	netif_start_queue(dev);
+	return 0;
+}
+
+static int bnep_net_close(struct net_device *dev)
+{
+	netif_stop_queue(dev);
+	return 0;
+}
+
+static void bnep_net_set_mc_list(struct net_device *dev)
+{
+#ifdef CONFIG_BT_BNEP_MC_FILTER
+	struct bnep_session *s = netdev_priv(dev);
+	struct sock *sk = s->sock->sk;
+	struct bnep_set_filter_req *r;
+	struct sk_buff *skb;
+	int size;
+
+	BT_DBG("%s mc_count %d", dev->name, netdev_mc_count(dev));
+
+	size = sizeof(*r) + (BNEP_MAX_MULTICAST_FILTERS + 1) * ETH_ALEN * 2;
+	skb  = alloc_skb(size, GFP_ATOMIC);
+	if (!skb) {
+		BT_ERR("%s Multicast list allocation failed", dev->name);
+		return;
+	}
+
+	r = (void *) skb->data;
+	__skb_put(skb, sizeof(*r));
+
+	r->type = BNEP_CONTROL;
+	r->ctrl = BNEP_FILTER_MULTI_ADDR_SET;
+
+	if (dev->flags & (IFF_PROMISC | IFF_ALLMULTI)) {
+		u8 start[ETH_ALEN] = { 0x01 };
+
+		/* Request all addresses */
+		__skb_put_data(skb, start, ETH_ALEN);
+		__skb_put_data(skb, dev->broadcast, ETH_ALEN);
+		r->len = htons(ETH_ALEN * 2);
+	} else {
+		struct netdev_hw_addr *ha;
+		int i, len = skb->len;
+
+		if (dev->flags & IFF_BROADCAST) {
+			__skb_put_data(skb, dev->broadcast, ETH_ALEN);
+			__skb_put_data(skb, dev->broadcast, ETH_ALEN);
+		}
+
+		/* FIXME: We should group addresses here. */
+
+		i = 0;
+		netdev_for_each_mc_addr(ha, dev) {
+			if (i == BNEP_MAX_MULTICAST_FILTERS)
+				break;
+			__skb_put_data(skb, ha->addr, ETH_ALEN);
+			__skb_put_data(skb, ha->addr, ETH_ALEN);
+
+			i++;
+		}
+		r->len = htons(skb->len - len);
+	}
+
+	skb_queue_tail(&sk->sk_write_queue, skb);
+	wake_up_interruptible(sk_sleep(sk));
+#endif
+}
+
+static int bnep_net_set_mac_addr(struct net_device *dev, void *arg)
+{
+	BT_DBG("%s", dev->name);
+	return 0;
+}
+
+static void bnep_net_timeout(struct net_device *dev, unsigned int txqueue)
+{
+	BT_DBG("net_timeout");
+	netif_wake_queue(dev);
+}
+
+#ifdef CONFIG_BT_BNEP_MC_FILTER
+static int bnep_net_mc_filter(struct sk_buff *skb, struct bnep_session *s)
+{
+	struct ethhdr *eh = (void *) skb->data;
+
+	if ((eh->h_dest[0] & 1) && !test_bit(bnep_mc_hash(eh->h_dest), (ulong *) &s->mc_filter))
+		return 1;
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_BT_BNEP_PROTO_FILTER
+/* Determine ether protocol. Based on eth_type_trans. */
+static u16 bnep_net_eth_proto(struct sk_buff *skb)
+{
+	struct ethhdr *eh = (void *) skb->data;
+	u16 proto = ntohs(eh->h_proto);
+
+	if (proto >= ETH_P_802_3_MIN)
+		return proto;
+
+	if (get_unaligned((__be16 *) skb->data) == htons(0xFFFF))
+		return ETH_P_802_3;
+
+	return ETH_P_802_2;
+}
+
+static int bnep_net_proto_filter(struct sk_buff *skb, struct bnep_session *s)
+{
+	u16 proto = bnep_net_eth_proto(skb);
+	struct bnep_proto_filter *f = s->proto_filter;
+	int i;
+
+	for (i = 0; i < BNEP_MAX_PROTO_FILTERS && f[i].end; i++) {
+		if (proto >= f[i].start && proto <= f[i].end)
+			return 0;
+	}
+
+	BT_DBG("BNEP: filtered skb %p, proto 0x%.4x", skb, proto);
+	return 1;
+}
+#endif
+
+static netdev_tx_t bnep_net_xmit(struct sk_buff *skb,
+				 struct net_device *dev)
+{
+	struct bnep_session *s = netdev_priv(dev);
+	struct sock *sk = s->sock->sk;
+
+	BT_DBG("skb %p, dev %p", skb, dev);
+
+#ifdef CONFIG_BT_BNEP_MC_FILTER
+	if (bnep_net_mc_filter(skb, s)) {
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+#endif
+
+#ifdef CONFIG_BT_BNEP_PROTO_FILTER
+	if (bnep_net_proto_filter(skb, s)) {
+		kfree_skb(skb);
+		return NETDEV_TX_OK;
+	}
+#endif
+
+	/*
+	 * We cannot send L2CAP packets from here as we are potentially in a bh.
+	 * So we have to queue them and wake up session thread which is sleeping
+	 * on the sk_sleep(sk).
+	 */
+	netif_trans_update(dev);
+	skb_queue_tail(&sk->sk_write_queue, skb);
+	wake_up_interruptible(sk_sleep(sk));
+
+	if (skb_queue_len(&sk->sk_write_queue) >= BNEP_TX_QUEUE_LEN) {
+		BT_DBG("tx queue is full");
+
+		/* Stop queuing.
+		 * Session thread will do netif_wake_queue() */
+		netif_stop_queue(dev);
+	}
+
+	return NETDEV_TX_OK;
+}
+
+static const struct net_device_ops bnep_netdev_ops = {
+	.ndo_open            = bnep_net_open,
+	.ndo_stop            = bnep_net_close,
+	.ndo_start_xmit	     = bnep_net_xmit,
+	.ndo_validate_addr   = eth_validate_addr,
+	.ndo_set_rx_mode     = bnep_net_set_mc_list,
+	.ndo_set_mac_address = bnep_net_set_mac_addr,
+	.ndo_tx_timeout      = bnep_net_timeout,
+
+};
+
+void bnep_net_setup(struct net_device *dev)
+{
+
+	eth_broadcast_addr(dev->broadcast);
+	dev->addr_len = ETH_ALEN;
+
+	ether_setup(dev);
+	dev->min_mtu = 0;
+	dev->max_mtu = ETH_MAX_MTU;
+	dev->priv_flags &= ~IFF_TX_SKB_SHARING;
+	dev->netdev_ops = &bnep_netdev_ops;
+
+	dev->watchdog_timeo  = HZ * 2;
+}