[Qemu-devel] [PATCH v5 2/3] rtl8139: add vlan tag extraction

[Jason Wang]

Benjamin Poirier writes:
 > Add support to the emulated hardware to extract vlan tags in packets
 > going from the network to the guest.
 > 
 > Signed-off-by: Benjamin Poirier <address@hidden>
 > Cc: Igor V. Kovalenko <address@hidden>
 > Cc: Jason Wang <address@hidden>
 > Cc: Michael S. Tsirkin <address@hidden>
 > Cc: Blue Swirl <address@hidden>
 > 
 > --
 > 
 > 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...)
 > ---
 >  hw/rtl8139.c |   86 
 > +++++++++++++++++++++++++++++++++++++++++++++------------
 >  1 files changed, 68 insertions(+), 18 deletions(-)
 > 
 > diff --git a/hw/rtl8139.c b/hw/rtl8139.c
 > index 3772ac1..55a386e 100644
 > --- a/hw/rtl8139.c
 > +++ b/hw/rtl8139.c
 > @@ -72,6 +72,16 @@
 >  #define MOD2(input, size) \
 >      ( ( input ) & ( size - 1 )  )
 >  
 > +#define ETHER_ADDR_LEN 6
 > +#define ETHER_TYPE_LEN 2
 > +#define ETH_HLEN (ETHER_ADDR_LEN * 2 + ETHER_TYPE_LEN)
 > +#define ETH_P_8021Q 0x8100      /* 802.1Q VLAN Extended Header  */
 > +#define ETH_P_IP    0x0800      /* Internet Protocol packet */
 > +#define ETH_MTU     1500
 > +
 > +#define VLAN_TCI_LEN 2
 > +#define VLAN_HLEN (ETHER_TYPE_LEN + VLAN_TCI_LEN)
 > +
 >  #if defined (DEBUG_RTL8139)
 >  #  define DEBUG_PRINT(x) do { printf x ; } while (0)
 >  #else
 > @@ -813,10 +823,13 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, 
 > const uint8_t *buf, size_
 >  {
 >      RTL8139State *s = DO_UPCAST(NICState, nc, nc)->opaque;
 >      int size = size_;
 > +    const uint8_t *dot1q_buf;
 > +    const uint8_t *next_part;
 > +    size_t next_part_size;
 >  
 >      uint32_t packet_header = 0;
 >  
 > -    uint8_t buf1[60];
 > +    uint8_t buf1[MIN_BUF_SIZE];
 >      static const uint8_t broadcast_macaddr[6] =
 >          { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 >  
 > @@ -928,14 +941,6 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, 
 > const uint8_t *buf, size_
 >          }
 >      }
 >  
 > -    /* if too small buffer, then expand it */
 > -    if (size < MIN_BUF_SIZE) {
 > -        memcpy(buf1, buf, size);
 > -        memset(buf1 + size, 0, MIN_BUF_SIZE - size);
 > -        buf = buf1;
 > -        size = MIN_BUF_SIZE;
 > -    }
 > -
 >      if (rtl8139_cp_receiver_enabled(s))
 >      {
 >          DEBUG_PRINT(("RTL8139: in C+ Rx mode ================\n"));
 > @@ -996,6 +1001,40 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, 
 > const uint8_t *buf, size_
 >  
 >          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 && be16_to_cpup((uint16_t *) next_part) 
 > ==
 > +            ETH_P_8021Q) {
 > +            dot1q_buf = next_part;
 > +            next_part += VLAN_HLEN;
 > +            size -= VLAN_HLEN;
 > +
 > +            rxdw1 &= ~CP_RX_VLAN_TAG_MASK;
 > +            /* BE + ~le_to_cpu()~ + cpu_to_le() = BE */
 > +            rxdw1 |= CP_RX_TAVA | le16_to_cpup((uint16_t *) &buf[ETH_HLEN]);
 > +
 > +            DEBUG_PRINT(("RTL8139: C+ Rx mode : extracted vlan tag with 
 > tci: "
 > +                    "%u\n", be16_to_cpup((uint16_t *) &buf[ETH_HLEN])));
 > +        } else {
 > +            /* reset VLAN tag flag */
 > +            rxdw1 &= ~CP_RX_TAVA;
 > +            dot1q_buf = NULL;
 > +        }
 > +        next_part_size = 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;
 > +
 > +            memcpy(buf1, next_part, next_part_size);
 > +            memset(buf1 + next_part_size, 0, tmp_size - next_part_size);
 > +            next_part = buf1;
 > +            next_part_size = tmp_size;
 > +            size = MIN_BUF_SIZE;
 > +        }
 > +
 >          /* TODO: scatter the packet over available receive ring descriptors 
 > space */
 >  
 >          if (size+4 > rx_space)
 > @@ -1017,7 +1056,17 @@ static ssize_t rtl8139_do_receive(VLANClientState 
 > *nc, const uint8_t *buf, size_
 >          target_phys_addr_t rx_addr = rtl8139_addr64(rxbufLO, rxbufHI);
 >  
 >          /* receive/copy to target memory */
 > -        cpu_physical_memory_write( rx_addr, buf, size );
 > +        if (dot1q_buf) {
 > +            cpu_physical_memory_write(rx_addr, buf, 2 * ETHER_ADDR_LEN);
 > +            val = crc32(0, buf, 2 * ETHER_ADDR_LEN);
 > +            val = crc32(val, dot1q_buf, VLAN_HLEN);
 > +            cpu_physical_memory_write(rx_addr + 2 * ETHER_ADDR_LEN, 
 > next_part,
 > +                next_part_size);
 > +            val = crc32(val, buf + 2 * ETHER_ADDR_LEN, next_part_size);
 > +        } else {
 > +            cpu_physical_memory_write(rx_addr, buf, size);

You does padding for buf1, but use buf here, so the it would be missed if you
have a non-vlan frame whose size is less than MIN_BUF_SIZE. Looks like the
following codes just work:

            cpu_physical_memory_write(rx_addr, buf, 2 * ETHER_ADDR_LEN);
            val = crc32(0, buf, 2 * ETHER_ADDR_LEN);
            if (dot1q_buf)
                val = crc32(val, dot1q_buf, VLAN_HLEN);
            cpu_physical_memory_write(rx_addr + 2 * ETHER_ADDR_LEN, next_part,
                next_part_size);
            val = crc32(val, buf + 2 * ETHER_ADDR_LEN, next_part_size);


 > +            val = crc32(0, buf, size);
 > +        }
 >  
 >          if (s->CpCmd & CPlusRxChkSum)
 >          {
 > @@ -1025,7 +1074,7 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, 
 > const uint8_t *buf, size_
 >          }
 >  
 >          /* write checksum */
 > -        val = cpu_to_le32(crc32(0, buf, size));
 > +        val = cpu_to_le32(val);
 >          cpu_physical_memory_write( rx_addr+size, (uint8_t *)&val, 4);
 >  
 >  /* first segment of received packet flag */
 > @@ -1070,9 +1119,6 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, 
 > const uint8_t *buf, size_
 >          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);
 > @@ -1099,6 +1145,14 @@ static ssize_t rtl8139_do_receive(VLANClientState 
 > *nc, const uint8_t *buf, size_
 >      {
 >          DEBUG_PRINT(("RTL8139: in ring Rx mode ================\n"));
 >  
 > +        /* if too small buffer, then expand it */
 > +        if (size < MIN_BUF_SIZE) {
 > +            memcpy(buf1, buf, size);
 > +            memset(buf1 + size, 0, MIN_BUF_SIZE - size);
 > +            buf = buf1;
 > +            size = MIN_BUF_SIZE;
 > +        }
 > +
 >          /* begin ring receiver mode */
 >          int avail = MOD2(s->RxBufferSize + s->RxBufPtr - s->RxBufAddr, 
 > s->RxBufferSize);
 >  
 > @@ -2066,10 +2120,6 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
 >          {
 >              DEBUG_PRINT(("RTL8139: +++ C+ mode offloaded task checksum\n"));
 >  
 > -            #define ETH_P_IP        0x0800          /* Internet Protocol 
 > packet     */
 > -            #define ETH_HLEN    14
 > -            #define ETH_MTU     1500
 > -
 >              /* ip packet header */
 >              ip_header *ip = NULL;
 >              int hlen = 0;
 > -- 
 > 1.7.2.3
 >