From 7ffa5c40d4ebe5d49a57f09a446ae1acf7a6d8b1 Mon Sep 17 00:00:00 2001
From: Xiao Wang <jasowang@redhat.com>
Date: Fri, 14 Oct 2011 10:33:16 +0200
Subject: [PATCH 1/5] e1000: multi-buffer packet support

RH-Author: Xiao Wang <jasowang@redhat.com>
Message-id: <20111014103315.30650.55407.stgit@amd-1216-8-1.englab.nay.redhat.com>
Patchwork-id: 34187
O-Subject: [RHEL5.8 qemu-kvm PATCH 1/3] e1000: multi-buffer packet support
Bugzilla: 703446
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>
RH-Acked-by: Avi Kivity <avi@redhat.com>
RH-Acked-by: Amos Kong <akong@redhat.com>

bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=703446
test status: ping -M do with the jumbo frame to guest, and stress the guest with
TCP/UDP stream
upstream: backport from (b19487e27ed3009df7f555998a454ba19aefd4b8):

    e1000: multi-buffer packet support

    e1000 supports multi-buffer packets larger than rxbuf_size.

    This fixes the following (on linux):
    - in guest: ifconfig eth1 mtu 16110
    - in host: ifconfig tap0 mtu 16110
               ping -s 16082 <guest-ip>

    Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
    Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
    Acked-by: Alex Williamson <alex.williamson@redhat.com>
    Acked-by: Kevin Wolf <kwolf@redhat.com>
    Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 qemu/hw/e1000.c |   41 +++++++++++++++++++++++++++++------------
 1 files changed, 29 insertions(+), 12 deletions(-)

Signed-off-by: Michal Novotny <mignov@gmail.com>
---
 qemu/hw/e1000.c |   41 +++++++++++++++++++++++++++++------------
 1 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/qemu/hw/e1000.c b/qemu/hw/e1000.c
index aa2e287..424546f 100644
--- a/qemu/hw/e1000.c
+++ b/qemu/hw/e1000.c
@@ -643,16 +643,13 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
     uint32_t rdh_start;
     uint16_t vlan_special = 0;
     uint8_t vlan_status = 0, vlan_offset = 0;
+    size_t desc_offset;
+    size_t desc_size;
+    size_t total_size;
 
     if (!(s->mac_reg[RCTL] & E1000_RCTL_EN))
         return;
 
-    if (size > s->rxbuf_size) {
-        DBGOUT(RX, "packet too large for buffers (%d > %d)\n", size,
-               s->rxbuf_size);
-        return;
-    }
-
     if (!receive_filter(s, buf, size))
         return;
 
@@ -665,9 +662,16 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
     }
 
     rdh_start = s->mac_reg[RDH];
-    size += fcs_len(s);
+    desc_offset = 0;
+    total_size = size + fcs_len(s);
     do {
+        desc_size = total_size - desc_offset;
+        if (desc_size > s->rxbuf_size) {
+            desc_size = s->rxbuf_size;
+        }
         if (s->mac_reg[RDH] == s->mac_reg[RDT] && s->check_rxov) {
+            /* Discard all data written so far */
+            s->mac_reg[RDH] = rdh_start;
             set_ics(s, 0, E1000_ICS_RXO);
             return;
         }
@@ -677,10 +681,23 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
         desc.special = vlan_special;
         desc.status |= (vlan_status | E1000_RXD_STAT_DD);
         if (desc.buffer_addr) {
-            cpu_physical_memory_write(le64_to_cpu(desc.buffer_addr),
-                                      (void *)(buf + vlan_offset), size);
-            desc.length = cpu_to_le16(size);
-            desc.status |= E1000_RXD_STAT_EOP|E1000_RXD_STAT_IXSM;
+            if (desc_offset < size) {
+                size_t copy_size = size - desc_offset;
+                if (copy_size > s->rxbuf_size) {
+                    copy_size = s->rxbuf_size;
+                }
+                cpu_physical_memory_write(le64_to_cpu(desc.buffer_addr),
+                                          (void *)(buf + desc_offset +
+                                                   vlan_offset),
+                                          copy_size);
+            }
+            desc_offset += desc_size;
+            if (desc_offset >= total_size) {
+                desc.length = cpu_to_le16(desc_size);
+                desc.status |= E1000_RXD_STAT_EOP | E1000_RXD_STAT_IXSM;
+            } else {
+                desc.length = cpu_to_le16(desc_size);
+            }
         } else // as per intel docs; skip descriptors with null buf addr
             DBGOUT(RX, "Null RX descriptor!!\n");
         cpu_physical_memory_write(base, (void *)&desc, sizeof(desc));
@@ -695,7 +712,7 @@ e1000_receive(void *opaque, const uint8_t *buf, int size)
             set_ics(s, 0, E1000_ICS_RXO);
             return;
         }
-    } while (desc.buffer_addr == 0);
+    } while (desc_offset < total_size);
 
     s->mac_reg[GPRC]++;
     s->mac_reg[TPR]++;
-- 
1.7.4.4