Re: [PATCH net-next v6 05/12] virtio_net: Query and set flow filter caps

[Paolo Abeni <pabeni@redhat.com>]

On 10/27/25 6:39 PM, Daniel Jurgens wrote:
> When probing a virtnet device, attempt to read the flow filter
> capabilities. In order to use the feature the caps must also
> be set. For now setting what was read is sufficient.
> 
> Signed-off-by: Daniel Jurgens <danielj@nvidia.com>
> Reviewed-by: Parav Pandit <parav@nvidia.com>
> Reviewed-by: Shahar Shitrit <shshitrit@nvidia.com>
> ---
> v4:
>     - Validate the length in the selector caps
>     - Removed __free usage.
>     - Removed for(int.
> v5:
>     - Remove unneed () after MAX_SEL_LEN macro (test bot)
> v6:
>     - Fix sparse warning "array of flexible structures" Jakub K/Simon H
>     - Use new variable and validate ff_mask_size before set_cap. MST
> ---
>  drivers/net/virtio_net.c           | 171 +++++++++++++++++++++++++++++
>  include/linux/virtio_admin.h       |   1 +
>  include/uapi/linux/virtio_net_ff.h |  91 +++++++++++++++
>  3 files changed, 263 insertions(+)
>  create mode 100644 include/uapi/linux/virtio_net_ff.h
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index a757cbcab87f..a9fde879fdbf 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -26,6 +26,9 @@
>  #include <net/netdev_rx_queue.h>
>  #include <net/netdev_queues.h>
>  #include <net/xdp_sock_drv.h>
> +#include <linux/virtio_admin.h>
> +#include <net/ipv6.h>
> +#include <net/ip.h>
>  
>  static int napi_weight = NAPI_POLL_WEIGHT;
>  module_param(napi_weight, int, 0444);
> @@ -281,6 +284,14 @@ static const struct virtnet_stat_desc virtnet_stats_tx_speed_desc_qstat[] = {
>  	VIRTNET_STATS_DESC_TX_QSTAT(speed, ratelimit_packets, hw_drop_ratelimits),
>  };
>  
> +struct virtnet_ff {
> +	struct virtio_device *vdev;
> +	bool ff_supported;
> +	struct virtio_net_ff_cap_data *ff_caps;
> +	struct virtio_net_ff_cap_mask_data *ff_mask;
> +	struct virtio_net_ff_actions *ff_actions;
> +};
> +
>  #define VIRTNET_Q_TYPE_RX 0
>  #define VIRTNET_Q_TYPE_TX 1
>  #define VIRTNET_Q_TYPE_CQ 2
> @@ -493,6 +504,8 @@ struct virtnet_info {
>  	struct failover *failover;
>  
>  	u64 device_stats_cap;
> +
> +	struct virtnet_ff ff;
>  };
>  
>  struct padded_vnet_hdr {
> @@ -6753,6 +6766,160 @@ static const struct xdp_metadata_ops virtnet_xdp_metadata_ops = {
>  	.xmo_rx_hash			= virtnet_xdp_rx_hash,
>  };
>  
> +static size_t get_mask_size(u16 type)
> +{
> +	switch (type) {
> +	case VIRTIO_NET_FF_MASK_TYPE_ETH:
> +		return sizeof(struct ethhdr);
> +	case VIRTIO_NET_FF_MASK_TYPE_IPV4:
> +		return sizeof(struct iphdr);
> +	case VIRTIO_NET_FF_MASK_TYPE_IPV6:
> +		return sizeof(struct ipv6hdr);
> +	case VIRTIO_NET_FF_MASK_TYPE_TCP:
> +		return sizeof(struct tcphdr);
> +	case VIRTIO_NET_FF_MASK_TYPE_UDP:
> +		return sizeof(struct udphdr);
> +	}
> +
> +	return 0;
> +}
> +
> +#define MAX_SEL_LEN (sizeof(struct ipv6hdr))
> +
> +static void virtnet_ff_init(struct virtnet_ff *ff, struct virtio_device *vdev)
> +{
> +	size_t ff_mask_size = sizeof(struct virtio_net_ff_cap_mask_data) +
> +			      sizeof(struct virtio_net_ff_selector) *
> +			      VIRTIO_NET_FF_MASK_TYPE_MAX;
> +	struct virtio_admin_cmd_query_cap_id_result *cap_id_list;
> +	struct virtio_net_ff_selector *sel;
> +	size_t real_ff_mask_size;
> +	int err;
> +	int i;
> +
> +	cap_id_list = kzalloc(sizeof(*cap_id_list), GFP_KERNEL);
> +	if (!cap_id_list)
> +		return;
> +
> +	err = virtio_admin_cap_id_list_query(vdev, cap_id_list);
> +	if (err)
> +		goto err_cap_list;
> +
> +	if (!(VIRTIO_CAP_IN_LIST(cap_id_list,
> +				 VIRTIO_NET_FF_RESOURCE_CAP) &&
> +	      VIRTIO_CAP_IN_LIST(cap_id_list,
> +				 VIRTIO_NET_FF_SELECTOR_CAP) &&
> +	      VIRTIO_CAP_IN_LIST(cap_id_list,
> +				 VIRTIO_NET_FF_ACTION_CAP)))
> +		goto err_cap_list;
> +
> +	ff->ff_caps = kzalloc(sizeof(*ff->ff_caps), GFP_KERNEL);
> +	if (!ff->ff_caps)
> +		goto err_cap_list;
> +
> +	err = virtio_admin_cap_get(vdev,
> +				   VIRTIO_NET_FF_RESOURCE_CAP,
> +				   ff->ff_caps,
> +				   sizeof(*ff->ff_caps));
> +
> +	if (err)
> +		goto err_ff;
> +
> +	/* VIRTIO_NET_FF_MASK_TYPE start at 1 */
> +	for (i = 1; i <= VIRTIO_NET_FF_MASK_TYPE_MAX; i++)
> +		ff_mask_size += get_mask_size(i);
> +
> +	ff->ff_mask = kzalloc(ff_mask_size, GFP_KERNEL);
> +	if (!ff->ff_mask)
> +		goto err_ff;
> +
> +	err = virtio_admin_cap_get(vdev,
> +				   VIRTIO_NET_FF_SELECTOR_CAP,
> +				   ff->ff_mask,
> +				   ff_mask_size);
> +
> +	if (err)
> +		goto err_ff_mask;
> +
> +	ff->ff_actions = kzalloc(sizeof(*ff->ff_actions) +
> +					VIRTIO_NET_FF_ACTION_MAX,
> +					GFP_KERNEL);
> +	if (!ff->ff_actions)
> +		goto err_ff_mask;
> +
> +	err = virtio_admin_cap_get(vdev,
> +				   VIRTIO_NET_FF_ACTION_CAP,
> +				   ff->ff_actions,
> +				   sizeof(*ff->ff_actions) + VIRTIO_NET_FF_ACTION_MAX);
> +
> +	if (err)
> +		goto err_ff_action;
> +
> +	err = virtio_admin_cap_set(vdev,
> +				   VIRTIO_NET_FF_RESOURCE_CAP,
> +				   ff->ff_caps,
> +				   sizeof(*ff->ff_caps));
> +	if (err)
> +		goto err_ff_action;
> +
> +	real_ff_mask_size = sizeof(struct virtio_net_ff_cap_mask_data);
> +	sel = (void *)&ff->ff_mask->selectors[0];
> +
> +	for (i = 0; i < ff->ff_mask->count; i++) {
> +		if (sel->length > MAX_SEL_LEN) {
> +			err = -EINVAL;
> +			goto err_ff_action;
> +		}
> +		real_ff_mask_size += sizeof(struct virtio_net_ff_selector) + sel->length;
> +		sel = (void *)sel + sizeof(*sel) + sel->length;
> +	}
> +
> +	if (real_ff_mask_size > ff_mask_size) {
> +		err = -EINVAL;
> +		goto err_ff_action;
> +	}
> +
> +	err = virtio_admin_cap_set(vdev,
> +				   VIRTIO_NET_FF_SELECTOR_CAP,
> +				   ff->ff_mask,
> +				   ff_mask_size);
> +	if (err)
> +		goto err_ff_action;
> +
> +	err = virtio_admin_cap_set(vdev,
> +				   VIRTIO_NET_FF_ACTION_CAP,
> +				   ff->ff_actions,
> +				   sizeof(*ff->ff_actions) + VIRTIO_NET_FF_ACTION_MAX);
> +	if (err)
> +		goto err_ff_action;
> +
> +	ff->vdev = vdev;
> +	ff->ff_supported = true;
> +
> +	kfree(cap_id_list);
> +
> +	return;
> +
> +err_ff_action:
> +	kfree(ff->ff_actions);
> +err_ff_mask:
> +	kfree(ff->ff_mask);
> +err_ff:
> +	kfree(ff->ff_caps);
> +err_cap_list:
> +	kfree(cap_id_list);

Minor nit: AFAICS the ff->ff_{caps,mask,actions} pointers can be left !=
NULL even after free. That should not cause issue at cleanup time, as
double free is protected by/avoided with 'ff_supported'.

Still it could foul kmemleak check. I think it would be better to either
clear such fields here or set such fields only on success (and work with
local variable up to that point).

Not a blocker anyway.

/P