Re: [PATCH 2/3] hw/net: e1000e: Correct the initial value of VET register

[Bin Meng]

On Fri, Jul 2, 2021 at 11:29 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/7/1 下午5:46, Bin Meng 写道:
> > From: Christina Wang <christina.wang@windriver.com>
> >
> > 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: Bin Meng <bmeng.cn@gmail.com>
> > ---
> >
> >   hw/net/e1000e_core.h |  2 --
> >   hw/net/e1000e.c      |  6 ++----
> >   hw/net/e1000e_core.c | 11 ++++++-----
> >   3 files changed, 8 insertions(+), 11 deletions(-)
> >
> > diff --git a/hw/net/e1000e_core.h b/hw/net/e1000e_core.h
> > index 4ddb4d2c39..07d722bc68 100644
> > --- a/hw/net/e1000e_core.h
> > +++ b/hw/net/e1000e_core.h
> > @@ -105,8 +105,6 @@ struct E1000Core {
> >       uint32_t itr_guest_value;
> >       uint32_t eitr_guest_value[E1000E_MSIX_VEC_NUM];
> >
> > -    uint16_t vet;
> > -
> >       uint8_t permanent_mac[ETH_ALEN];
> >
> >       NICState *owner_nic;
> > diff --git a/hw/net/e1000e.c b/hw/net/e1000e.c
> > index a8a77eca95..1797e4a7cb 100644
> > --- a/hw/net/e1000e.c
> > +++ b/hw/net/e1000e.c
> > @@ -602,8 +602,8 @@ static const VMStateDescription 
> > e1000e_vmstate_intr_timer = {
> >
> >   static const VMStateDescription e1000e_vmstate = {
> >       .name = "e1000e",
> > -    .version_id = 1,
> > -    .minimum_version_id = 1,
> > +    .version_id = 2,
> > +    .minimum_version_id = 2,
> >       .pre_save = e1000e_pre_save,
> >       .post_load = e1000e_post_load,
> >       .fields = (VMStateField[]) {
> > @@ -645,8 +645,6 @@ static const VMStateDescription e1000e_vmstate = {
> >           VMSTATE_UINT32_ARRAY(core.eitr_guest_value, E1000EState,
> >                                E1000E_MSIX_VEC_NUM),
> >
> > -        VMSTATE_UINT16(core.vet, E1000EState),
>
>
> This is not the suggested way. We'd better not bump version in this case.
>
> How about update vet during post_load?

But core.vet is removed in this patch. Not sure how to handle this?

Regards,
Bin