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/net/can/vcan.c | 212 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 drivers/net/can/vcan.c (limited to 'drivers/net/can/vcan.c') diff --git a/drivers/net/can/vcan.c b/drivers/net/can/vcan.c new file mode 100644 index 000000000..76e6b7b5c --- /dev/null +++ b/drivers/net/can/vcan.c @@ -0,0 +1,212 @@ +/* vcan.c - Virtual CAN interface + * + * Copyright (c) 2002-2017 Volkswagen Group Electronic Research + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of Volkswagen nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * Alternatively, provided that this notice is retained in full, this + * software may be distributed under the terms of the GNU General + * Public License ("GPL") version 2, in which case the provisions of the + * GPL apply INSTEAD OF those given above. + * + * The provided data structures and external interfaces from this code + * are not restricted to be used by modules with a GPL compatible license. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH + * DAMAGE. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define DRV_NAME "vcan" + +MODULE_DESCRIPTION("virtual CAN interface"); +MODULE_LICENSE("Dual BSD/GPL"); +MODULE_AUTHOR("Urs Thuermann "); +MODULE_ALIAS_RTNL_LINK(DRV_NAME); + +/* CAN test feature: + * Enable the echo on driver level for testing the CAN core echo modes. + * See Documentation/networking/can.rst for details. + */ + +static bool echo; /* echo testing. Default: 0 (Off) */ +module_param(echo, bool, 0444); +MODULE_PARM_DESC(echo, "Echo sent frames (for testing). Default: 0 (Off)"); + +static void vcan_rx(struct sk_buff *skb, struct net_device *dev) +{ + struct net_device_stats *stats = &dev->stats; + + stats->rx_packets++; + stats->rx_bytes += can_skb_get_data_len(skb); + + skb->pkt_type = PACKET_BROADCAST; + skb->dev = dev; + skb->ip_summed = CHECKSUM_UNNECESSARY; + + netif_rx(skb); +} + +static netdev_tx_t vcan_tx(struct sk_buff *skb, struct net_device *dev) +{ + struct net_device_stats *stats = &dev->stats; + unsigned int len; + int loop; + + if (can_dropped_invalid_skb(dev, skb)) + return NETDEV_TX_OK; + + len = can_skb_get_data_len(skb); + stats->tx_packets++; + stats->tx_bytes += len; + + /* set flag whether this packet has to be looped back */ + loop = skb->pkt_type == PACKET_LOOPBACK; + + skb_tx_timestamp(skb); + + if (!echo) { + /* no echo handling available inside this driver */ + if (loop) { + /* only count the packets here, because the + * CAN core already did the echo for us + */ + stats->rx_packets++; + stats->rx_bytes += len; + } + consume_skb(skb); + return NETDEV_TX_OK; + } + + /* perform standard echo handling for CAN network interfaces */ + + if (loop) { + skb = can_create_echo_skb(skb); + if (!skb) + return NETDEV_TX_OK; + + /* receive with packet counting */ + vcan_rx(skb, dev); + } else { + /* no looped packets => no counting */ + consume_skb(skb); + } + return NETDEV_TX_OK; +} + +static void vcan_set_cap_info(struct net_device *dev) +{ + u32 can_cap = CAN_CAP_CC; + + if (dev->mtu > CAN_MTU) + can_cap |= CAN_CAP_FD; + + if (dev->mtu >= CANXL_MIN_MTU) + can_cap |= CAN_CAP_XL; + + can_set_cap(dev, can_cap); +} + +static int vcan_change_mtu(struct net_device *dev, int new_mtu) +{ + /* Do not allow changing the MTU while running */ + if (dev->flags & IFF_UP) + return -EBUSY; + + if (new_mtu != CAN_MTU && new_mtu != CANFD_MTU && + !can_is_canxl_dev_mtu(new_mtu)) + return -EINVAL; + + WRITE_ONCE(dev->mtu, new_mtu); + vcan_set_cap_info(dev); + return 0; +} + +static const struct net_device_ops vcan_netdev_ops = { + .ndo_start_xmit = vcan_tx, + .ndo_change_mtu = vcan_change_mtu, +}; + +static const struct ethtool_ops vcan_ethtool_ops = { + .get_ts_info = ethtool_op_get_ts_info, +}; + +static void vcan_setup(struct net_device *dev) +{ + dev->type = ARPHRD_CAN; + dev->mtu = CANXL_MTU; + dev->hard_header_len = 0; + dev->addr_len = 0; + dev->tx_queue_len = 0; + dev->flags = IFF_NOARP; + can_set_ml_priv(dev, netdev_priv(dev)); + vcan_set_cap_info(dev); + + /* set flags according to driver capabilities */ + if (echo) + dev->flags |= IFF_ECHO; + + dev->netdev_ops = &vcan_netdev_ops; + dev->ethtool_ops = &vcan_ethtool_ops; + dev->needs_free_netdev = true; +} + +static struct rtnl_link_ops vcan_link_ops __read_mostly = { + .kind = DRV_NAME, + .priv_size = sizeof(struct can_ml_priv), + .setup = vcan_setup, +}; + +static __init int vcan_init_module(void) +{ + pr_info("Virtual CAN interface driver\n"); + + if (echo) + pr_info("enabled echo on driver level.\n"); + + return rtnl_link_register(&vcan_link_ops); +} + +static __exit void vcan_cleanup_module(void) +{ + rtnl_link_unregister(&vcan_link_ops); +} + +module_init(vcan_init_module); +module_exit(vcan_cleanup_module); -- cgit v1.3.1