[Qemu-devel] [PATCH v4 1/2] 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 |  100 +++++++++++++++++++++++++++++++++++++++++++++++-----------
 1 files changed, 81 insertions(+), 19 deletions(-)

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index a22530c..6e770bd 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -68,6 +68,16 @@
 #if defined(RTL8139_CALCULATE_RXCRC)
 /* For crc32 */
 #include <zlib.h>
+
+static inline uLong rtl8139_crc32(uLong crc, const Bytef *buf, uInt len)
+{
+    return crc32(crc, buf, len);
+}
+#else
+static inline uLong rtl8139_crc32(uLong crc, const Bytef *buf, uInt len)
+{
+    return 0;
+}
 #endif
 
 #define SET_MASKED(input, mask, curr) \
@@ -77,6 +87,14 @@
 #define MOD2(input, size) \
     ( ( input ) & ( size - 1 )  )
 
+#define ETHER_ADDR_LEN 6
+#define ETHER_TYPE_LEN 2
+#define ETHER_HDR_LEN (ETHER_ADDR_LEN * 2 + ETHER_TYPE_LEN)
+#define ETHERTYPE_VLAN 0x8100
+
+#define VLAN_TCI_LEN 2
+#define VLAN_HDR_LEN (ETHER_TYPE_LEN + VLAN_TCI_LEN)
+
 #if defined (DEBUG_RTL8139)
 #  define DEBUG_PRINT(x) do { printf x ; } while (0)
 #else
@@ -818,10 +836,13 @@ 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 };
 
@@ -933,14 +954,6 @@ 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"));
@@ -1001,6 +1014,41 @@ 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 *)
+                &buf[ETHER_ADDR_LEN * 2]) == ETHERTYPE_VLAN) {
+            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;
+            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)
@@ -1022,7 +1070,18 @@ 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 (unlikely(dot1q_buf)) {
+            cpu_physical_memory_write(rx_addr, buf, 2 * ETHER_ADDR_LEN);
+            val = rtl8139_crc32(0, buf, 2 * ETHER_ADDR_LEN);
+            val = rtl8139_crc32(val, dot1q_buf, VLAN_HDR_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);
+        }
 
         if (s->CpCmd & CPlusRxChkSum)
         {
@@ -1031,9 +1090,7 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf, size_
 
         /* write checksum */
 #if defined (RTL8139_CALCULATE_RXCRC)
-        val = cpu_to_le32(crc32(0, buf, size));
-#else
-        val = 0;
+        val = cpu_to_le32(val);
 #endif
         cpu_physical_memory_write( rx_addr+size, (uint8_t *)&val, 4);
 
@@ -1079,9 +1136,6 @@ 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);
@@ -1108,6 +1162,14 @@ 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);
 
@@ -1133,13 +1195,13 @@ static ssize_t rtl8139_do_receive(VLANClientState *nc, const uint8_t *buf, size_
 
         rtl8139_write_buffer(s, (uint8_t *)&val, 4);
 
+        /* receive/copy to target memory */
         rtl8139_write_buffer(s, buf, size);
+        val = rtl8139_crc32(0, buf, size);
 
         /* write checksum */
 #if defined (RTL8139_CALCULATE_RXCRC)
-        val = cpu_to_le32(crc32(0, buf, size));
-#else
-        val = 0;
+        val = cpu_to_le32(val);
 #endif
 
         rtl8139_write_buffer(s, (uint8_t *)&val, 4);
-- 
1.7.2.3