e1000e: Reset packet state after emptying Tx queue

Keeping Tx packet state after the transmit queue is emptied has some
problems:
- The datasheet says the descriptors can be reused after the transmit
  queue is emptied, but the Tx packet state may keep references to them.
- The Tx packet state cannot be migrated so it can be reset anytime the
  migration happens.

Always reset Tx packet state always after the queue is emptied.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/e1000e_core.c

@@ -959,6 +959,8 @@ e1000e_start_xmit(E1000ECore *core, const E1000E_TxRing *txr)
     if (!ide || !e1000e_intrmgr_delay_tx_causes(core, &cause)) {
         e1000e_set_interrupt_cause(core, cause);
     }
+
+    net_tx_pkt_reset(txr->tx->tx_pkt, net_tx_pkt_unmap_frag_pci, core->owner);
 }
 
 static bool
@@ -3389,8 +3391,6 @@ e1000e_core_pci_uninit(E1000ECore *core)
     qemu_del_vm_change_state_handler(core->vmstate);
 
     for (i = 0; i < E1000E_NUM_QUEUES; i++) {
-        net_tx_pkt_reset(core->tx[i].tx_pkt,
-                         net_tx_pkt_unmap_frag_pci, core->owner);
         net_tx_pkt_uninit(core->tx[i].tx_pkt);
     }
 
@@ -3515,8 +3515,6 @@ static void e1000e_reset(E1000ECore *core, bool sw)
     e1000x_reset_mac_addr(core->owner_nic, core->mac, core->permanent_mac);
 
     for (i = 0; i < ARRAY_SIZE(core->tx); i++) {
-        net_tx_pkt_reset(core->tx[i].tx_pkt,
-                         net_tx_pkt_unmap_frag_pci, core->owner);
         memset(&core->tx[i].props, 0, sizeof(core->tx[i].props));
         core->tx[i].skip_cp = false;
     }