vmxnet3: Pad short frames to minimum size (60 bytes)

When running VMware ESXi under qemu-kvm the guest discards frames
that are too short. Short ARP Requests will be dropped, this prevents
guests on the same bridge as VMware ESXi from communicating. This patch
simply adds the padding on the network device itself.

Signed-off-by: Ben Draper <ben@xrsa.net>
Reviewed-by: Dmitry Fleytman <dmitry@daynix.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
(cherry picked from commit 40a87c6c9b11ef9c14e0301f76abf0eb2582f08e)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>

diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c
index 77bea6f89f626c3a0b26320b54227504b47ea08d..ae3e50f4305cbd5aa165d1f46a39475d4119dba8 100644 (file)
--- a/hw/net/vmxnet3.c
+++ b/hw/net/vmxnet3.c
@@ -34,6 +34,7 @@
 
 #define PCI_DEVICE_ID_VMWARE_VMXNET3_REVISION 0x1
 #define VMXNET3_MSIX_BAR_SIZE 0x2000
+#define MIN_BUF_SIZE 60
 
 #define VMXNET3_BAR0_IDX      (0)
 #define VMXNET3_BAR1_IDX      (1)
@@ -1871,12 +1872,21 @@ vmxnet3_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 {
     VMXNET3State *s = qemu_get_nic_opaque(nc);
     size_t bytes_indicated;
+    uint8_t min_buf[MIN_BUF_SIZE];
 
     if (!vmxnet3_can_receive(nc)) {
         VMW_PKPRN("Cannot receive now");
         return -1;
     }
 
+    /* Pad to minimum Ethernet frame length */
+    if (size < sizeof(min_buf)) {
+        memcpy(min_buf, buf, size);
+        memset(&min_buf[size], 0, sizeof(min_buf) - size);
+        buf = min_buf;
+        size = sizeof(min_buf);
+    }
+
     if (s->peer_has_vhdr) {
         vmxnet_rx_pkt_set_vhdr(s->rx_pkt, (struct virtio_net_hdr *)buf);
         buf += sizeof(struct virtio_net_hdr);