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

[Benjamin Poirier <benjamin.poirier@gmail.com>]

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.)
---
 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;
-    }
-
     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);
 
-- 
1.7.2.3