hw/net: e1000e: Correct the initial value of VET register

The initial value of VLAN Ether Type (VET) register is 0x8100, as per
the manual and real hardware.

While Linux e1000e driver always writes VET register to 0x8100, it is
not always the case for everyone. Drivers relying on the reset value
of VET won't be able to transmit and receive VLAN frames in QEMU.

Unlike e1000 in QEMU, e1000e uses a field 'vet' in "struct E1000Core"
to cache the value of VET register, but the cache only gets updated
when VET register is written. To always get a consistent VET value
no matter VET is written or remains its reset value, drop the 'vet'
field and use 'core->mac[VET]' directly.

Reported-by: Markus Carlstedt <markus.carlstedt@windriver.com>
Signed-off-by: Christina Wang <christina.wang@windriver.com>
Signed-off-by: Bin Meng <bin.meng@windriver.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/core/machine.c

@@ -42,6 +42,7 @@ GlobalProperty hw_compat_6_0[] = {
     { "i8042", "extended-state", "false"},
     { "nvme-ns", "eui64-default", "off"},
     { "e1000", "init-vet", "off" },
+    { "e1000e", "init-vet", "off" },
 };
 const size_t hw_compat_6_0_len = G_N_ELEMENTS(hw_compat_6_0);
 

hw/net/e1000e.c

@@ -35,6 +35,7 @@
 
 #include "qemu/osdep.h"
 #include "qemu/units.h"
+#include "net/eth.h"
 #include "net/net.h"
 #include "net/tap.h"
 #include "qemu/module.h"
@@ -79,7 +80,7 @@ struct E1000EState {
     bool disable_vnet;
 
     E1000ECore core;
-
+    bool init_vet;
 };
 
 #define E1000E_MMIO_IDX     0
@@ -527,6 +528,10 @@ static void e1000e_qdev_reset(DeviceState *dev)
     trace_e1000e_cb_qdev_reset();
 
     e1000e_core_reset(&s->core);
+
+    if (s->init_vet) {
+        s->core.mac[VET] = ETH_P_VLAN;
+    }
 }
 
 static int e1000e_pre_save(void *opaque)
@@ -666,6 +671,7 @@ static Property e1000e_properties[] = {
                         e1000e_prop_subsys_ven, uint16_t),
     DEFINE_PROP_SIGNED("subsys", E1000EState, subsys, 0,
                         e1000e_prop_subsys, uint16_t),
+    DEFINE_PROP_BOOL("init-vet", E1000EState, init_vet, true),
     DEFINE_PROP_END_OF_LIST(),
 };
 

hw/net/e1000e_core.c

@@ -731,7 +731,7 @@ e1000e_process_tx_desc(E1000ECore *core,
             if (e1000x_vlan_enabled(core->mac) &&
                 e1000x_is_vlan_txd(txd_lower)) {
                 net_tx_pkt_setup_vlan_header_ex(tx->tx_pkt,
-                    le16_to_cpu(dp->upper.fields.special), core->vet);
+                    le16_to_cpu(dp->upper.fields.special), core->mac[VET]);
             }
             if (e1000e_tx_pkt_send(core, tx, queue_index)) {
                 e1000e_on_tx_done_update_stats(core, tx->tx_pkt);
@@ -1012,7 +1012,7 @@ e1000e_receive_filter(E1000ECore *core, const uint8_t *buf, int size)
 {
     uint32_t rctl = core->mac[RCTL];
 
-    if (e1000x_is_vlan_packet(buf, core->vet) &&
+    if (e1000x_is_vlan_packet(buf, core->mac[VET]) &&
         e1000x_vlan_rx_filter_enabled(core->mac)) {
         uint16_t vid = lduw_be_p(buf + 14);
         uint32_t vfta = ldl_le_p((uint32_t *)(core->mac + VFTA) +
@@ -1686,7 +1686,7 @@ e1000e_receive_iov(E1000ECore *core, const struct iovec *iov, int iovcnt)
     }
 
     net_rx_pkt_attach_iovec_ex(core->rx_pkt, iov, iovcnt, iov_ofs,
-                               e1000x_vlan_enabled(core->mac), core->vet);
+                               e1000x_vlan_enabled(core->mac), core->mac[VET]);
 
     e1000e_rss_parse_packet(core, core->rx_pkt, &rss_info);
     e1000e_rx_ring_init(core, &rxr, rss_info.queue);
@@ -2397,8 +2397,7 @@ static void
 e1000e_set_vet(E1000ECore *core, int index, uint32_t val)
 {
     core->mac[VET] = val & 0xffff;
-    core->vet = le16_to_cpu(core->mac[VET]);
-    trace_e1000e_vlan_vet(core->vet);
+    trace_e1000e_vlan_vet(core->mac[VET]);
 }
 
 static void