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Message-ID: <202602071211.N0SvyotM-lkp@intel.com>
Date: Sat, 7 Feb 2026 13:03:51 +0800
From: kernel test robot <lkp@...el.com>
To: Srujana Challa <schalla@...vell.com>, netdev@...r.kernel.org,
virtualization@...ts.linux.dev
Cc: llvm@...ts.linux.dev, oe-kbuild-all@...ts.linux.dev, pabeni@...hat.com,
mst@...hat.com, jasowang@...hat.com, xuanzhuo@...ux.alibaba.com,
eperezma@...hat.com, davem@...emloft.net, edumazet@...gle.com,
kuba@...nel.org, ndabilpuram@...vell.com, kshankar@...vell.com,
schalla@...vell.com
Subject: Re: [PATCH v2 net-next] virtio_net: Improve RSS key size validation
and use NETDEV_RSS_KEY_LEN
Hi Srujana,
kernel test robot noticed the following build warnings:
[auto build test WARNING on net-next/main]
url: https://github.com/intel-lab-lkp/linux/commits/Srujana-Challa/virtio_net-Improve-RSS-key-size-validation-and-use-NETDEV_RSS_KEY_LEN/20260206-200801
base: net-next/main
patch link: https://lore.kernel.org/r/20260206120154.2548079-1-schalla%40marvell.com
patch subject: [PATCH v2 net-next] virtio_net: Improve RSS key size validation and use NETDEV_RSS_KEY_LEN
config: riscv-defconfig (https://download.01.org/0day-ci/archive/20260207/202602071211.N0SvyotM-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 9b8addffa70cee5b2acc5454712d9cf78ce45710)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260207/202602071211.N0SvyotM-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602071211.N0SvyotM-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> drivers/net/virtio_net.c:6841:31: warning: result of comparison of constant 256 with expression of type 'u8' (aka 'unsigned char') is always false [-Wtautological-constant-out-of-range-compare]
6841 | } else if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
| ~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 warning generated.
vim +6841 drivers/net/virtio_net.c
6699
6700 static int virtnet_probe(struct virtio_device *vdev)
6701 {
6702 int i, err = -ENOMEM;
6703 struct net_device *dev;
6704 struct virtnet_info *vi;
6705 u16 max_queue_pairs;
6706 int mtu = 0;
6707
6708 /* Find if host supports multiqueue/rss virtio_net device */
6709 max_queue_pairs = 1;
6710 if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
6711 max_queue_pairs =
6712 virtio_cread16(vdev, offsetof(struct virtio_net_config, max_virtqueue_pairs));
6713
6714 /* We need at least 2 queue's */
6715 if (max_queue_pairs < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
6716 max_queue_pairs > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX ||
6717 !virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
6718 max_queue_pairs = 1;
6719
6720 /* Allocate ourselves a network device with room for our info */
6721 dev = alloc_etherdev_mq(sizeof(struct virtnet_info), max_queue_pairs);
6722 if (!dev)
6723 return -ENOMEM;
6724
6725 /* Set up network device as normal. */
6726 dev->priv_flags |= IFF_UNICAST_FLT | IFF_LIVE_ADDR_CHANGE |
6727 IFF_TX_SKB_NO_LINEAR;
6728 dev->netdev_ops = &virtnet_netdev;
6729 dev->stat_ops = &virtnet_stat_ops;
6730 dev->features = NETIF_F_HIGHDMA;
6731
6732 dev->ethtool_ops = &virtnet_ethtool_ops;
6733 SET_NETDEV_DEV(dev, &vdev->dev);
6734
6735 /* Do we support "hardware" checksums? */
6736 if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
6737 /* This opens up the world of extra features. */
6738 dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
6739 if (csum)
6740 dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
6741
6742 if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
6743 dev->hw_features |= NETIF_F_TSO
6744 | NETIF_F_TSO_ECN | NETIF_F_TSO6;
6745 }
6746 /* Individual feature bits: what can host handle? */
6747 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO4))
6748 dev->hw_features |= NETIF_F_TSO;
6749 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_TSO6))
6750 dev->hw_features |= NETIF_F_TSO6;
6751 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_ECN))
6752 dev->hw_features |= NETIF_F_TSO_ECN;
6753 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_USO))
6754 dev->hw_features |= NETIF_F_GSO_UDP_L4;
6755
6756 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO)) {
6757 dev->hw_features |= NETIF_F_GSO_UDP_TUNNEL;
6758 dev->hw_enc_features = dev->hw_features;
6759 }
6760 if (dev->hw_features & NETIF_F_GSO_UDP_TUNNEL &&
6761 virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO_CSUM)) {
6762 dev->hw_features |= NETIF_F_GSO_UDP_TUNNEL_CSUM;
6763 dev->hw_enc_features |= NETIF_F_GSO_UDP_TUNNEL_CSUM;
6764 }
6765
6766 dev->features |= NETIF_F_GSO_ROBUST;
6767
6768 if (gso)
6769 dev->features |= dev->hw_features;
6770 /* (!csum && gso) case will be fixed by register_netdev() */
6771 }
6772
6773 /* 1. With VIRTIO_NET_F_GUEST_CSUM negotiation, the driver doesn't
6774 * need to calculate checksums for partially checksummed packets,
6775 * as they're considered valid by the upper layer.
6776 * 2. Without VIRTIO_NET_F_GUEST_CSUM negotiation, the driver only
6777 * receives fully checksummed packets. The device may assist in
6778 * validating these packets' checksums, so the driver won't have to.
6779 */
6780 dev->features |= NETIF_F_RXCSUM;
6781
6782 if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
6783 virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO6))
6784 dev->features |= NETIF_F_GRO_HW;
6785 if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS))
6786 dev->hw_features |= NETIF_F_GRO_HW;
6787
6788 dev->vlan_features = dev->features;
6789 dev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
6790 NETDEV_XDP_ACT_XSK_ZEROCOPY;
6791
6792 /* MTU range: 68 - 65535 */
6793 dev->min_mtu = MIN_MTU;
6794 dev->max_mtu = MAX_MTU;
6795
6796 /* Configuration may specify what MAC to use. Otherwise random. */
6797 if (virtio_has_feature(vdev, VIRTIO_NET_F_MAC)) {
6798 u8 addr[ETH_ALEN];
6799
6800 virtio_cread_bytes(vdev,
6801 offsetof(struct virtio_net_config, mac),
6802 addr, ETH_ALEN);
6803 eth_hw_addr_set(dev, addr);
6804 } else {
6805 eth_hw_addr_random(dev);
6806 dev_info(&vdev->dev, "Assigned random MAC address %pM\n",
6807 dev->dev_addr);
6808 }
6809
6810 /* Set up our device-specific information */
6811 vi = netdev_priv(dev);
6812 vi->dev = dev;
6813 vi->vdev = vdev;
6814 vdev->priv = vi;
6815
6816 INIT_WORK(&vi->config_work, virtnet_config_changed_work);
6817 INIT_WORK(&vi->rx_mode_work, virtnet_rx_mode_work);
6818
6819 if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF)) {
6820 vi->mergeable_rx_bufs = true;
6821 dev->xdp_features |= NETDEV_XDP_ACT_RX_SG;
6822 }
6823
6824 if (virtio_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT))
6825 vi->has_rss_hash_report = true;
6826
6827 if (virtio_has_feature(vdev, VIRTIO_NET_F_RSS))
6828 vi->has_rss = true;
6829
6830 if (vi->has_rss || vi->has_rss_hash_report) {
6831 vi->rss_key_size =
6832 virtio_cread8(vdev, offsetof(struct virtio_net_config, rss_max_key_size));
6833
6834 /* Spec requires at least 40 bytes */
6835 if (vi->rss_key_size < VIRTIO_NET_RSS_MIN_KEY_SIZE) {
6836 dev_warn(&vdev->dev,
6837 "rss_max_key_size=%u is less than spec minimum %u, disabling RSS\n",
6838 vi->rss_key_size, VIRTIO_NET_RSS_MIN_KEY_SIZE);
6839 vi->has_rss = false;
6840 vi->has_rss_hash_report = false;
> 6841 } else if (vi->rss_key_size > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
6842 dev_warn(&vdev->dev,
6843 "rss_max_key_size=%u exceeds driver limit %u, disabling RSS\n",
6844 vi->rss_key_size, VIRTIO_NET_RSS_MAX_KEY_SIZE);
6845 vi->has_rss = false;
6846 vi->has_rss_hash_report = false;
6847 } else {
6848 vi->rss_indir_table_size =
6849 virtio_cread16(vdev, offsetof(struct virtio_net_config,
6850 rss_max_indirection_table_length));
6851 vi->rss_hash_types_supported =
6852 virtio_cread32(vdev, offsetof(struct virtio_net_config,
6853 supported_hash_types));
6854 vi->rss_hash_types_supported &=
6855 ~(VIRTIO_NET_RSS_HASH_TYPE_IP_EX |
6856 VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
6857 VIRTIO_NET_RSS_HASH_TYPE_UDP_EX);
6858
6859 dev->hw_features |= NETIF_F_RXHASH;
6860 dev->xdp_metadata_ops = &virtnet_xdp_metadata_ops;
6861 }
6862 }
6863
6864 vi->rss_hdr = devm_kzalloc(&vdev->dev, virtnet_rss_hdr_size(vi), GFP_KERNEL);
6865 if (!vi->rss_hdr) {
6866 err = -ENOMEM;
6867 goto free;
6868 }
6869
6870 if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO) ||
6871 virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO))
6872 vi->hdr_len = sizeof(struct virtio_net_hdr_v1_hash_tunnel);
6873 else if (vi->has_rss_hash_report)
6874 vi->hdr_len = sizeof(struct virtio_net_hdr_v1_hash);
6875 else if (virtio_has_feature(vdev, VIRTIO_NET_F_MRG_RXBUF) ||
6876 virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
6877 vi->hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
6878 else
6879 vi->hdr_len = sizeof(struct virtio_net_hdr);
6880
6881 if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO_CSUM))
6882 vi->rx_tnl_csum = true;
6883 if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_UDP_TUNNEL_GSO))
6884 vi->rx_tnl = true;
6885 if (virtio_has_feature(vdev, VIRTIO_NET_F_HOST_UDP_TUNNEL_GSO))
6886 vi->tx_tnl = true;
6887
6888 if (virtio_has_feature(vdev, VIRTIO_F_ANY_LAYOUT) ||
6889 virtio_has_feature(vdev, VIRTIO_F_VERSION_1))
6890 vi->any_header_sg = true;
6891
6892 if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ))
6893 vi->has_cvq = true;
6894
6895 mutex_init(&vi->cvq_lock);
6896
6897 if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) {
6898 mtu = virtio_cread16(vdev,
6899 offsetof(struct virtio_net_config,
6900 mtu));
6901 if (mtu < dev->min_mtu) {
6902 /* Should never trigger: MTU was previously validated
6903 * in virtnet_validate.
6904 */
6905 dev_err(&vdev->dev,
6906 "device MTU appears to have changed it is now %d < %d",
6907 mtu, dev->min_mtu);
6908 err = -EINVAL;
6909 goto free;
6910 }
6911
6912 dev->mtu = mtu;
6913 dev->max_mtu = mtu;
6914 }
6915
6916 virtnet_set_big_packets(vi, mtu);
6917
6918 if (vi->any_header_sg)
6919 dev->needed_headroom = vi->hdr_len;
6920
6921 /* Enable multiqueue by default */
6922 if (num_online_cpus() >= max_queue_pairs)
6923 vi->curr_queue_pairs = max_queue_pairs;
6924 else
6925 vi->curr_queue_pairs = num_online_cpus();
6926 vi->max_queue_pairs = max_queue_pairs;
6927
6928 /* Allocate/initialize the rx/tx queues, and invoke find_vqs */
6929 err = init_vqs(vi);
6930 if (err)
6931 goto free;
6932
6933 if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_NOTF_COAL)) {
6934 vi->intr_coal_rx.max_usecs = 0;
6935 vi->intr_coal_tx.max_usecs = 0;
6936 vi->intr_coal_rx.max_packets = 0;
6937
6938 /* Keep the default values of the coalescing parameters
6939 * aligned with the default napi_tx state.
6940 */
6941 if (vi->sq[0].napi.weight)
6942 vi->intr_coal_tx.max_packets = 1;
6943 else
6944 vi->intr_coal_tx.max_packets = 0;
6945 }
6946
6947 if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_VQ_NOTF_COAL)) {
6948 /* The reason is the same as VIRTIO_NET_F_NOTF_COAL. */
6949 for (i = 0; i < vi->max_queue_pairs; i++)
6950 if (vi->sq[i].napi.weight)
6951 vi->sq[i].intr_coal.max_packets = 1;
6952
6953 err = virtnet_init_irq_moder(vi);
6954 if (err)
6955 goto free;
6956 }
6957
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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