RE: [PATCH v2 27/41] net/eth: Always add VLAN tag

[Sriram Yagnaraman]

> -----Original Message-----
> From: Akihiko Odaki <akihiko.odaki@daynix.com>
> Sent: Thursday, 20 April 2023 07:47
> Cc: Sriram Yagnaraman <sriram.yagnaraman@est.tech>; Jason Wang
> <jasowang@redhat.com>; Dmitry Fleytman <dmitry.fleytman@gmail.com>;
> Michael S . Tsirkin <mst@redhat.com>; Alex Bennée
> <alex.bennee@linaro.org>; Philippe Mathieu-Daudé <philmd@linaro.org>;
> Thomas Huth <thuth@redhat.com>; Wainer dos Santos Moschetta
> <wainersm@redhat.com>; Beraldo Leal <bleal@redhat.com>; Cleber Rosa
> <crosa@redhat.com>; Laurent Vivier <lvivier@redhat.com>; Paolo Bonzini
> <pbonzini@redhat.com>; qemu-devel@nongnu.org; Tomasz Dzieciol
> <t.dzieciol@partner.samsung.com>; Akihiko Odaki
> <akihiko.odaki@daynix.com>
> Subject: [PATCH v2 27/41] net/eth: Always add VLAN tag
> 
> It is possible to have another VLAN tag even if the packet is already tagged.
> 
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>  include/net/eth.h   |  4 ++--
>  hw/net/net_tx_pkt.c | 16 +++++++---------
>  net/eth.c           | 22 ++++++----------------
>  3 files changed, 15 insertions(+), 27 deletions(-)
> 
> diff --git a/include/net/eth.h b/include/net/eth.h index
> 95ff24d6b8..048e434685 100644
> --- a/include/net/eth.h
> +++ b/include/net/eth.h
> @@ -353,8 +353,8 @@ eth_strip_vlan_ex(const struct iovec *iov, int iovcnt,
> size_t iovoff,  uint16_t  eth_get_l3_proto(const struct iovec *l2hdr_iov, int
> iovcnt, size_t l2hdr_len);
> 
> -void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
> -    uint16_t vlan_ethtype, bool *is_new);
> +void eth_setup_vlan_headers(struct eth_header *ehdr, size_t *ehdr_size,
> +                            uint16_t vlan_tag, uint16_t vlan_ethtype);
> 
> 
>  uint8_t eth_get_gso_type(uint16_t l3_proto, uint8_t *l3_hdr, uint8_t 
> l4proto);
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c index
> ce6b102391..af8f77a3f0 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -40,7 +40,10 @@ struct NetTxPkt {
> 
>      struct iovec *vec;
> 
> -    uint8_t l2_hdr[ETH_MAX_L2_HDR_LEN];
> +    struct {
> +        struct eth_header eth;
> +        struct vlan_header vlan[3];
> +    } l2_hdr;
>      union {
>          struct ip_header ip;
>          struct ip6_header ip6;
> @@ -365,18 +368,13 @@ bool net_tx_pkt_build_vheader(struct NetTxPkt
> *pkt, bool tso_enable,  void net_tx_pkt_setup_vlan_header_ex(struct NetTxPkt
> *pkt,
>      uint16_t vlan, uint16_t vlan_ethtype)  {
> -    bool is_new;
>      assert(pkt);
> 
>      eth_setup_vlan_headers(pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_base,
> -        vlan, vlan_ethtype, &is_new);
> +                           &pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len,
> +                           vlan, vlan_ethtype);
> 
> -    /* update l2hdrlen */
> -    if (is_new) {
> -        pkt->hdr_len += sizeof(struct vlan_header);
> -        pkt->vec[NET_TX_PKT_L2HDR_FRAG].iov_len +=
> -            sizeof(struct vlan_header);
> -    }
> +    pkt->hdr_len += sizeof(struct vlan_header);
>  }
> 
>  bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, void *base, size_t
> len) diff --git a/net/eth.c b/net/eth.c index f7ffbda600..5307978486 100644
> --- a/net/eth.c
> +++ b/net/eth.c
> @@ -21,26 +21,16 @@
>  #include "net/checksum.h"
>  #include "net/tap.h"
> 
> -void eth_setup_vlan_headers(struct eth_header *ehdr, uint16_t vlan_tag,
> -    uint16_t vlan_ethtype, bool *is_new)
> +void eth_setup_vlan_headers(struct eth_header *ehdr, size_t *ehdr_size,
> +                            uint16_t vlan_tag, uint16_t vlan_ethtype)
>  {
>      struct vlan_header *vhdr = PKT_GET_VLAN_HDR(ehdr);
> 
> -    switch (be16_to_cpu(ehdr->h_proto)) {
> -    case ETH_P_VLAN:
> -    case ETH_P_DVLAN:
> -        /* vlan hdr exists */
> -        *is_new = false;
> -        break;
> -
> -    default:
> -        /* No VLAN header, put a new one */
> -        vhdr->h_proto = ehdr->h_proto;
> -        ehdr->h_proto = cpu_to_be16(vlan_ethtype);
> -        *is_new = true;
> -        break;
> -    }
> +    memmove(vhdr + 1, vhdr, *ehdr_size - ETH_HLEN);

Do we need a check that we are not overflowing the vlan array size?

>      vhdr->h_tci = cpu_to_be16(vlan_tag);
> +    vhdr->h_proto = ehdr->h_proto;
> +    ehdr->h_proto = cpu_to_be16(vlan_ethtype);
> +    *ehdr_size += sizeof(*vhdr);
>  }
> 
>  uint8_t
> --
> 2.40.0