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Re: [Qemu-devel] [PATCH v2 1/2] rtl8139: add vlan tag insertion


From: Anthony Liguori
Subject: Re: [Qemu-devel] [PATCH v2 1/2] rtl8139: add vlan tag insertion
Date: Tue, 16 Nov 2010 14:06:13 -0600
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Lightning/1.0b1 Thunderbird/3.0.10

On 11/08/2010 07:46 PM, Benjamin Poirier wrote:
Add support to the emulated hardware to add vlan tags in packets going
from the guest to the network.

Signed-off-by: Benjamin Poirier<address@hidden>
Cc: Igor V. Kovalenko<address@hidden>
---
Changes since v1:
* moved the debug print statement inside the if block and reworded
   accordingly. (as suggested by Igor)

  hw/rtl8139.c |   45 ++++++++++++++++++++++++++++++++++-----------
  1 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index d92981d..b599945 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -47,6 +47,8 @@
   *                                  Darwin)
   */

+#include<net/ethernet.h>
+
  #include "hw.h"
  #include "pci.h"
  #include "qemu-timer.h"
@@ -58,6 +60,10 @@

  #define PCI_FREQUENCY 33000000L

+/* bytes in VLAN tag */
+#define VLAN_TCI_LEN 2
+#define VLAN_HDR_LEN (ETHER_TYPE_LEN + VLAN_TCI_LEN)
+
  /* debug RTL8139 card C+ mode only */
  //#define DEBUG_RTL8139CP 1

@@ -1913,7 +1919,6 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)

      cpu_physical_memory_read(cplus_tx_ring_desc,    (uint8_t *)&val, 4);
      txdw0 = le32_to_cpu(val);
-    /* TODO: implement VLAN tagging support, VLAN tag data is read to txdw1 */
      cpu_physical_memory_read(cplus_tx_ring_desc+4,  (uint8_t *)&val, 4);
      txdw1 = le32_to_cpu(val);
      cpu_physical_memory_read(cplus_tx_ring_desc+8,  (uint8_t *)&val, 4);
@@ -1925,9 +1930,6 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
             descriptor,
             txdw0, txdw1, txbufLO, txbufHI));

-    /* TODO: the following discard cast should clean clang analyzer output */
-    (void)txdw1;
-
  /* w0 ownership flag */
  #define CP_TX_OWN (1<<31)
  /* w0 end of ring flag */
@@ -1951,8 +1953,8 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
  /* w0 bits 0...15 : buffer size */
  #define CP_TX_BUFFER_SIZE (1<<16)
  #define CP_TX_BUFFER_SIZE_MASK (CP_TX_BUFFER_SIZE - 1)
-/* w1 tag available flag */
-#define CP_RX_TAGC (1<<17)
+/* w1 add tag flag */
+#define CP_TX_TAGC (1<<17)
  /* w1 bits 0...15 : VLAN tag */
  #define CP_TX_VLAN_TAG_MASK ((1<<16) - 1)
  /* w2 low  32bit of Rx buffer ptr */
@@ -1978,12 +1980,21 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)

      DEBUG_PRINT(("RTL8139: +++ C+ Tx mode : transmitting from descriptor 
%d\n", descriptor));

+    int vlan_extra_size = 0;
      if (txdw0&  CP_TX_FS)
      {
          DEBUG_PRINT(("RTL8139: +++ C+ Tx mode : descriptor %d is first segment 
descriptor\n", descriptor));

          /* reset internal buffer offset */
          s->cplus_txbuffer_offset = 0;
+
+        if (txdw1&  CP_TX_TAGC)
+        {
+            vlan_extra_size = VLAN_HDR_LEN;
+
+            DEBUG_PRINT(("RTL8139: +++ C+ Tx mode : inserting vlan tag with "
+                    "tci: %u\n", bswap16(txdw1&  CP_TX_VLAN_TAG_MASK)));
+        }
      }

      int txsize = txdw0&  CP_TX_BUFFER_SIZE_MASK;
@@ -1992,14 +2003,15 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
      /* make sure we have enough space to assemble the packet */
      if (!s->cplus_txbuffer)
      {
-        s->cplus_txbuffer_len = CP_TX_BUFFER_SIZE;
+        s->cplus_txbuffer_len = CP_TX_BUFFER_SIZE + VLAN_HDR_LEN;
          s->cplus_txbuffer = qemu_malloc(s->cplus_txbuffer_len);
          s->cplus_txbuffer_offset = 0;

          DEBUG_PRINT(("RTL8139: +++ C+ mode transmission buffer allocated space 
%d\n", s->cplus_txbuffer_len));
      }

-    while (s->cplus_txbuffer&&  s->cplus_txbuffer_offset + txsize>= 
s->cplus_txbuffer_len)
+    while (s->cplus_txbuffer&&  s->cplus_txbuffer_offset + txsize +
+        vlan_extra_size>= s->cplus_txbuffer_len)
      {
          s->cplus_txbuffer_len += CP_TX_BUFFER_SIZE;
          s->cplus_txbuffer = qemu_realloc(s->cplus_txbuffer, 
s->cplus_txbuffer_len);
@@ -2025,6 +2037,20 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
      DEBUG_PRINT(("RTL8139: +++ C+ mode transmit reading %d bytes from host memory at 
%016" PRIx64 " to offset %d\n",
                   txsize, (uint64_t)tx_addr, s->cplus_txbuffer_offset));

+    if (vlan_extra_size&&  txsize>= 2 * ETHER_ADDR_LEN)
+    {
+        /* copy addresses */
+        cpu_physical_memory_read(tx_addr, s->cplus_txbuffer, 2 *
+            ETHER_ADDR_LEN);
+        tx_addr += 2 * ETHER_ADDR_LEN;
+        txsize -= 2 * ETHER_ADDR_LEN;
+        /* insert vlan tag */
+        *(uint16_t *)(s->cplus_txbuffer + 2 * ETHER_ADDR_LEN) =
+            cpu_to_be16(ETHERTYPE_VLAN);
+        *(uint16_t *)(s->cplus_txbuffer + 2 * ETHER_ADDR_LEN + ETHER_TYPE_LEN)
+            = cpu_to_le16(txdw1&  CP_TX_VLAN_TAG_MASK);

This looks wrong. You check for txsize >= 2 * ETHER_ADDR_LEN but then you assign at 2 * ETHER_ADDR_LEN. This is a potential overflow, no?

Regards,

Anthony Liguori

+        s->cplus_txbuffer_offset += 2 * ETHER_ADDR_LEN + VLAN_HDR_LEN;
+    }
      cpu_physical_memory_read(tx_addr, s->cplus_txbuffer + 
s->cplus_txbuffer_offset, txsize);
      s->cplus_txbuffer_offset += txsize;

@@ -2053,9 +2079,6 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
      /* update ring data */
      val = cpu_to_le32(txdw0);
      cpu_physical_memory_write(cplus_tx_ring_desc,    (uint8_t *)&val, 4);
-    /* TODO: implement VLAN tagging support, VLAN tag data is read to txdw1 */
-//    val = cpu_to_le32(txdw1);
-//    cpu_physical_memory_write(cplus_tx_ring_desc+4,&val, 4);

      /* Now decide if descriptor being processed is holding the last segment 
of packet */
      if (txdw0&  CP_TX_LS)




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