Re: [Qemu-devel] [PATCH v3 2/2] rtl8139: add vlan tag extraction

[Jason Wang <jasowang@redhat.com>]

On 02/26/2011 08:40 AM, Benjamin Poirier wrote:
> Add support to the emulated hardware to extract vlan tags in packets
> going from the network to the guest.
>
> Signed-off-by: Benjamin Poirier<benjamin.poirier@gmail.com>
> Cc: Igor V. Kovalenko<igor.v.kovalenko@gmail.com>
> Cc: Jason Wang<jasowang@redhat.com>
> Cc: Michael S. Tsirkin<mst@redhat.com>
>
> --
>
> AFAIK, extraction is optional to get vlans working. The driver
> requests rx detagging but should not assume that it was done. Under
> Linux, the mac layer will catch the vlan ethertype. I only added this
> part for completeness (to emulate the hardware more truthfully.)

Linux driver use the NETIF_F_HW_VLAN_RX by default, so it's needed.

> ---
>   hw/rtl8139.c |   89 +++++++++++++++++++++++++++++++++++++++++-----------------
>   1 files changed, 63 insertions(+), 26 deletions(-)
>
> diff --git a/hw/rtl8139.c b/hw/rtl8139.c
> index 35ccd3d..f3aaebc 100644
> --- a/hw/rtl8139.c
> +++ b/hw/rtl8139.c
> @@ -835,10 +835,11 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>       RTL8139State *s = DO_UPCAST(NICState, nc, nc)->opaque;
>       int size_ = buf_size + (dot1q_buf ? VLAN_HDR_LEN : 0);
>       int size = size_;
> +    const uint8_t *next_part;
> +    size_t next_part_size;
>
>       uint32_t packet_header = 0;
>
> -    uint8_t buf1[60];
>       static const uint8_t broadcast_macaddr[6] =
>           { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
>
> @@ -950,21 +951,6 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>           }
>       }
>
> -    /* if too small buffer, then expand it */
> -    if (size<  MIN_BUF_SIZE) {
> -        if (unlikely(dot1q_buf)) {
> -            memcpy(buf1, buf, 2 * ETHER_ADDR_LEN);
> -            memcpy(buf1 + 2 * ETHER_ADDR_LEN, dot1q_buf, VLAN_HDR_LEN);
> -            memcpy(buf1 + 2 * ETHER_ADDR_LEN + VLAN_HDR_LEN, buf + 2 *
> -                ETHER_ADDR_LEN, buf_size - 2 * ETHER_ADDR_LEN);
> -        } else {
> -            memcpy(buf1, buf, size);
> -        }
> -        memset(buf1 + size, 0, MIN_BUF_SIZE - size);
> -        buf = buf1;
> -        size = MIN_BUF_SIZE;
> -    }
> -

Since the your tx loopback changes depends on rx changes, I suggest you 
to put rx patch first which can also make review easier.

>       if (rtl8139_cp_receiver_enabled(s))
>       {
>           DEBUG_PRINT(("RTL8139: in C+ Rx mode ================\n"));
> @@ -1025,6 +1011,44 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>
>           uint32_t rx_space = rxdw0&  CP_RX_BUFFER_SIZE_MASK;
>
> +        /* write VLAN info to descriptor variables */
> +        /* next_part starts right after the vlan header (if any), at the
> +         * ethertype for the payload */
> +        next_part =&buf[ETHER_ADDR_LEN * 2];
> +        if (s->CpCmd&  CPlusRxVLAN&&  (dot1q_buf || be16_to_cpup((uint16_t *)
> +&buf[ETHER_ADDR_LEN * 2]) == ETHERTYPE_VLAN)) {
> +            if (!dot1q_buf) {
> +                /* the tag is in the buffer */
> +                dot1q_buf =&buf[ETHER_ADDR_LEN * 2];
> +                next_part += VLAN_HDR_LEN;
> +            }
> +            size -= VLAN_HDR_LEN;
> +
> +            rxdw1&= ~CP_RX_VLAN_TAG_MASK;
> +            /* BE + ~le_to_cpu()~ + cpu_to_le() = BE */
> +            rxdw1 |= CP_RX_TAVA | le16_to_cpup((uint16_t *)
> +&buf[ETHER_HDR_LEN]);
> +
> +            DEBUG_PRINT(("RTL8139: C+ Rx mode : extracted vlan tag with tci: "
> +                    "%u\n", be16_to_cpup((uint16_t *)&buf[ETHER_HDR_LEN])));
> +        } else {
> +            /* reset VLAN tag flag */
> +            rxdw1&= ~CP_RX_TAVA;
> +        }
> +        next_part_size = buf + buf_size - next_part;
> +
> +        /* if too small buffer, then expand it */
> +        if (size<  MIN_BUF_SIZE) {
> +            size_t tmp_size = MIN_BUF_SIZE - ETHER_ADDR_LEN * 2;
> +            uint8_t *tmp = alloca(tmp_size);
> +
> +            memcpy(tmp, next_part, next_part_size);
> +            memset(tmp + next_part_size, 0, tmp_size - next_part_size);
> +            next_part = tmp;
> +            next_part_size = tmp_size;
> +            size = MIN_BUF_SIZE;
> +        }
> +
>           /* TODO: scatter the packet over available receive ring descriptors space */
>
>           if (size+4>  rx_space)
> @@ -1049,14 +1073,11 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>           if (unlikely(dot1q_buf)) {
>               cpu_physical_memory_write(rx_addr, buf, 2 * ETHER_ADDR_LEN);
>               val = rtl8139_crc32(0, buf, 2 * ETHER_ADDR_LEN);
> -            cpu_physical_memory_write(rx_addr + 2 * ETHER_ADDR_LEN, dot1q_buf,
> -                VLAN_HDR_LEN);
>               val = rtl8139_crc32(val, dot1q_buf, VLAN_HDR_LEN);
> -            cpu_physical_memory_write(rx_addr + 2 * ETHER_ADDR_LEN +
> -                VLAN_HDR_LEN, buf + 2 * ETHER_ADDR_LEN, buf_size - 2 *
> -                ETHER_ADDR_LEN);
> -            val = rtl8139_crc32(val, buf + 2 * ETHER_ADDR_LEN, buf_size - 2 *
> -                ETHER_ADDR_LEN);
> +            cpu_physical_memory_write(rx_addr + 2 * ETHER_ADDR_LEN, next_part,
> +                next_part_size);
> +            val = rtl8139_crc32(val, buf + 2 * ETHER_ADDR_LEN,
> +                next_part_size);
>           } else {
>               cpu_physical_memory_write(rx_addr, buf, size);
>               val = rtl8139_crc32(0, buf, size);
> @@ -1115,9 +1136,6 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>           rxdw0&= ~CP_RX_BUFFER_SIZE_MASK;
>           rxdw0 |= (size+4);
>
> -        /* reset VLAN tag flag */
> -        rxdw1&= ~CP_RX_TAVA;
> -
>           /* update ring data */
>           val = cpu_to_le32(rxdw0);
>           cpu_physical_memory_write(cplus_rx_ring_desc,    (uint8_t *)&val, 4);
> @@ -1144,6 +1162,25 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf,
>       {
>           DEBUG_PRINT(("RTL8139: in ring Rx mode ================\n"));
>
> +        /* if too small buffer, then expand it */
> +        if (size<  MIN_BUF_SIZE) {
> +            uint8_t *tmp;
> +
> +            tmp = alloca(MIN_BUF_SIZE);
> +            if (unlikely(dot1q_buf)) {
> +                memcpy(tmp, buf, 2 * ETHER_ADDR_LEN);
> +                memcpy(tmp + 2 * ETHER_ADDR_LEN, dot1q_buf, VLAN_HDR_LEN);
> +                memcpy(tmp + 2 * ETHER_ADDR_LEN + VLAN_HDR_LEN, buf + 2 *
> +                    ETHER_ADDR_LEN, buf_size - 2 * ETHER_ADDR_LEN);
> +            } else {
> +                memcpy(tmp, buf, size);
> +            }
> +            memset(tmp + size, 0, MIN_BUF_SIZE - size);
> +            buf = tmp;
> +            size = MIN_BUF_SIZE;
> +            dot1q_buf = NULL;
> +        }
> +
>           /* begin ring receiver mode */
>           int avail = MOD2(s->RxBufferSize + s->RxBufPtr - s->RxBufAddr, s->RxBufferSize);
>