commit b0d9ffcd0251161c7c92f94804dcf599dfa3edeb
author Michael Contreras <michael@inetric.com> Sun Dec 02 20:11:22 2012 -0800
committer Anthony Liguori <aliguori@us.ibm.com> Mon Dec 03 08:14:10 2012 -0600
tree 6081c6f2c86125234555973f643fce06a932f127
parent 01bbd8bf2caced5cb07939669f58d3a7bcc78092

e1000: Discard packets that are too long if !SBP and !LPE

The e1000_receive function for the e1000 needs to discard packets longer than
1522 bytes if the SBP and LPE flags are disabled. The linux driver assumes
this behavior and allocates memory based on this assumption.

Signed-off-by: Michael Contreras <michael@inetric.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/e1000.c

diff --git a/hw/e1000.c b/hw/e1000.c
index cb7e7e8..5537ad2 100644
--- a/hw/e1000.c
+++ b/hw/e1000.c
@@ -59,6 +59,9 @@
 #define PNPMMIO_SIZE      0x20000
 #define MIN_BUF_SIZE      60 /* Min. octets in an ethernet frame sans FCS */
 
+/* this is the size past which hardware will drop packets when setting LPE=0 */
+#define MAXIMUM_ETHERNET_VLAN_SIZE 1522
+
 /*
  * HW models:
  *  E1000_DEV_ID_82540EM works with Windows and Linux
@@ -805,6 +808,13 @@
         size = sizeof(min_buf);
     }
 
+    /* Discard oversized packets if !LPE and !SBP. */
+    if (size > MAXIMUM_ETHERNET_VLAN_SIZE
+        && !(s->mac_reg[RCTL] & E1000_RCTL_LPE)
+        && !(s->mac_reg[RCTL] & E1000_RCTL_SBP)) {
+        return size;
+    }
+
     if (!receive_filter(s, buf, size))
         return size;