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

[Benjamin Poirier <benjamin.poirier@polymtl.ca>]

Add support to the emulated hardware to remove vlan tags in packets
going from the network to the guest.

Signed-off-by: Benjamin Poirier <benjamin.poirier@polymtl.ca>
Cc: Igor V. Kovalenko <igor.v.kovalenko@gmail.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..?).
---
 hw/rtl8139.c |   41 ++++++++++++++++++++++++++++++++++++++---
 1 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index ac294da..557a460 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -1024,6 +1024,44 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf, size_
 
         target_phys_addr_t rx_addr = rtl8139_addr64(rxbufLO, rxbufHI);
 
+        if (s->CpCmd & CPlusRxVLAN && size >= ETHER_ADDR_LEN * 2 +
+            VLAN_HDR_LEN && be16_to_cpup((uint16_t *) &buf[ETHER_ADDR_LEN *
+                2]) == ETHERTYPE_VLAN)
+        {
+            size_t new_size = size - VLAN_HDR_LEN;
+
+            rxdw1 &= ~CP_RX_VLAN_TAG_MASK;
+            rxdw1 |= CP_RX_TAVA |
+                le16_to_cpup((uint16_t *)&buf[ETHER_HDR_LEN]);
+
+            if (buf == buf1 || new_size < MIN_BUF_SIZE)
+            {
+                /* move the end and pad */
+                memmove((uint8_t *)buf + ETHER_ADDR_LEN * 2, buf +
+                    ETHER_ADDR_LEN * 2 + VLAN_HDR_LEN, new_size -
+                    ETHER_ADDR_LEN * 2);
+                memset((uint8_t *)buf + new_size, 0, MIN_BUF_SIZE - new_size);
+                size = MIN_BUF_SIZE;
+            }
+            else
+            {
+                /* move the beginning */
+                memmove((uint8_t *)buf + VLAN_HDR_LEN, buf, ETHER_ADDR_LEN *
+                    2);
+                buf += VLAN_HDR_LEN;
+                size = new_size;
+            }
+        }
+        else
+        {
+            /* reset VLAN tag flag */
+            rxdw1 &= ~CP_RX_TAVA;
+        }
+
+        DEBUG_PRINT(("RTL8139: C+ Rx mode : removed vlan tag: %u tci: %u\n",
+                !!(rxdw1 & CP_RX_TAVA), bswap16(rxdw1 &
+                    CP_RX_VLAN_TAG_MASK)));
+
         /* receive/copy to target memory */
         cpu_physical_memory_write( rx_addr, buf, size );
 
@@ -1082,9 +1120,6 @@ 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);
-- 
1.7.2.3