Re: [PATCH v5 21/29] hw/net/net_tx_pkt: Automatically determine if virtio-net header is used

[Jason Wang <jasowang@redhat.com>]

在 2023/2/1 11:35, Akihiko Odaki 写道:
> The new function qemu_get_using_vnet_hdr() allows to automatically
> determine if virtio-net header is used.
>
> Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> ---
>   hw/net/e1000e_core.c |  3 +--
>   hw/net/net_tx_pkt.c  | 19 ++++++++++---------
>   hw/net/net_tx_pkt.h  |  3 +--
>   hw/net/vmxnet3.c     |  6 ++----
>   4 files changed, 14 insertions(+), 17 deletions(-)
>
> diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
> index 38d374fba3..954a007151 100644
> --- a/hw/net/e1000e_core.c
> +++ b/hw/net/e1000e_core.c
> @@ -3376,8 +3376,7 @@ e1000e_core_pci_realize(E1000ECore     *core,
>           qemu_add_vm_change_state_handler(e1000e_vm_state_change, core);
>   
>       for (i = 0; i < E1000E_NUM_QUEUES; i++) {
> -        net_tx_pkt_init(&core->tx[i].tx_pkt, core->owner,
> -                        E1000E_MAX_TX_FRAGS, core->has_vnet);
> +        net_tx_pkt_init(&core->tx[i].tx_pkt, core->owner, E1000E_MAX_TX_FRAGS);
>       }
>   
>       net_rx_pkt_init(&core->rx_pkt, core->has_vnet);
> diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
> index 8a23899a4d..cf46c8457f 100644
> --- a/hw/net/net_tx_pkt.c
> +++ b/hw/net/net_tx_pkt.c
> @@ -35,7 +35,6 @@ struct NetTxPkt {
>       PCIDevice *pci_dev;
>   
>       struct virtio_net_hdr virt_hdr;
> -    bool has_virt_hdr;


So this requires implicit coupling of NetTxPkt and a NetClientState (not 
self contained). This may work now but probably not the future e.g when 
two packets were queued in a list when one packet has a vnet header but 
another doesn't?

Thanks


>   
>       struct iovec *raw;
>       uint32_t raw_frags;
> @@ -59,7 +58,7 @@ struct NetTxPkt {
>   };
>   
>   void net_tx_pkt_init(struct NetTxPkt **pkt, PCIDevice *pci_dev,
> -    uint32_t max_frags, bool has_virt_hdr)
> +    uint32_t max_frags)
>   {
>       struct NetTxPkt *p = g_malloc0(sizeof *p);
>   
> @@ -71,10 +70,8 @@ void net_tx_pkt_init(struct NetTxPkt **pkt, PCIDevice *pci_dev,
>   
>       p->max_payload_frags = max_frags;
>       p->max_raw_frags = max_frags;
> -    p->has_virt_hdr = has_virt_hdr;
>       p->vec[NET_TX_PKT_VHDR_FRAG].iov_base = &p->virt_hdr;
> -    p->vec[NET_TX_PKT_VHDR_FRAG].iov_len =
> -        p->has_virt_hdr ? sizeof p->virt_hdr : 0;
> +    p->vec[NET_TX_PKT_VHDR_FRAG].iov_len = sizeof p->virt_hdr;
>       p->vec[NET_TX_PKT_L2HDR_FRAG].iov_base = &p->l2_hdr;
>       p->vec[NET_TX_PKT_L3HDR_FRAG].iov_base = &p->l3_hdr;
>   
> @@ -617,9 +614,11 @@ static bool net_tx_pkt_do_sw_fragmentation(struct NetTxPkt *pkt,
>   
>   bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
>   {
> +    bool using_vnet_hdr = qemu_get_using_vnet_hdr(nc->peer);
> +
>       assert(pkt);
>   
> -    if (!pkt->has_virt_hdr &&
> +    if (!using_vnet_hdr &&
>           pkt->virt_hdr.flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
>           net_tx_pkt_do_sw_csum(pkt);
>       }
> @@ -636,11 +635,13 @@ bool net_tx_pkt_send(struct NetTxPkt *pkt, NetClientState *nc)
>           }
>       }
>   
> -    if (pkt->has_virt_hdr ||
> +    if (using_vnet_hdr ||
>           pkt->virt_hdr.gso_type == VIRTIO_NET_HDR_GSO_NONE) {
> +        int index = using_vnet_hdr ?
> +                    NET_TX_PKT_VHDR_FRAG : NET_TX_PKT_L2HDR_FRAG;
>           net_tx_pkt_fix_ip6_payload_len(pkt);
> -        net_tx_pkt_sendv(pkt, nc, pkt->vec,
> -            pkt->payload_frags + NET_TX_PKT_PL_START_FRAG);
> +        net_tx_pkt_sendv(pkt, nc, pkt->vec + index,
> +            pkt->payload_frags + NET_TX_PKT_PL_START_FRAG - index);
>           return true;
>       }
>   
> diff --git a/hw/net/net_tx_pkt.h b/hw/net/net_tx_pkt.h
> index 2e38a5fa69..8d3faa42fb 100644
> --- a/hw/net/net_tx_pkt.h
> +++ b/hw/net/net_tx_pkt.h
> @@ -32,10 +32,9 @@ struct NetTxPkt;
>    * @pkt:            packet pointer
>    * @pci_dev:        PCI device processing this packet
>    * @max_frags:      max tx ip fragments
> - * @has_virt_hdr:   device uses virtio header.
>    */
>   void net_tx_pkt_init(struct NetTxPkt **pkt, PCIDevice *pci_dev,
> -    uint32_t max_frags, bool has_virt_hdr);
> +    uint32_t max_frags);
>   
>   /**
>    * Clean all tx packet resources.
> diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
> index c63bbb59bd..8c3f5d6e14 100644
> --- a/hw/net/vmxnet3.c
> +++ b/hw/net/vmxnet3.c
> @@ -1521,8 +1521,7 @@ static void vmxnet3_activate_device(VMXNET3State *s)
>   
>       /* Preallocate TX packet wrapper */
>       VMW_CFPRN("Max TX fragments is %u", s->max_tx_frags);
> -    net_tx_pkt_init(&s->tx_pkt, PCI_DEVICE(s),
> -                    s->max_tx_frags, s->peer_has_vhdr);
> +    net_tx_pkt_init(&s->tx_pkt, PCI_DEVICE(s), s->max_tx_frags);
>       net_rx_pkt_init(&s->rx_pkt, s->peer_has_vhdr);
>   
>       /* Read rings memory locations for RX queues */
> @@ -2402,8 +2401,7 @@ static int vmxnet3_post_load(void *opaque, int version_id)
>   {
>       VMXNET3State *s = opaque;
>   
> -    net_tx_pkt_init(&s->tx_pkt, PCI_DEVICE(s),
> -                    s->max_tx_frags, s->peer_has_vhdr);
> +    net_tx_pkt_init(&s->tx_pkt, PCI_DEVICE(s), s->max_tx_frags);
>       net_rx_pkt_init(&s->rx_pkt, s->peer_has_vhdr);
>   
>       if (s->msix_used) {