Re: [PATCH] e1000e: set RX desc status with DD flag in a separate operation

[dinghui]

On 2022/9/9 10:40, Jason Wang wrote:
> On Sat, Aug 27, 2022 at 12:06 AM Ding Hui <dinghui@sangfor.com.cn> wrote:
> > Like commit 034d00d48581 ("e1000: set RX descriptor status in
> > a separate operation"), there is also same issue in e1000e, which
> > would cause lost packets or stop sending packets to VM with DPDK.
> >
> > Do similar fix in e1000e.
> >
> > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/402
> > Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
> > ---
> >   hw/net/e1000e_core.c | 54 +++++++++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 53 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/net/e1000e_core.c b/hw/net/e1000e_core.c
> > index 208e3e0d79..b8038e4014 100644
> > --- a/hw/net/e1000e_core.c
> > +++ b/hw/net/e1000e_core.c
> > @@ -1364,6 +1364,58 @@ struct NetRxPkt *pkt, const E1000E_RSSInfo *rss_info,
> >       }
> >   }
> >
> > +static inline void
> > +e1000e_pci_dma_write_rx_desc(E1000ECore *core, dma_addr_t addr,
> > +                             uint8_t *desc, dma_addr_t len)
> > +{
> > +    PCIDevice *dev = core->owner;
> > +
> > +    if (e1000e_rx_use_legacy_descriptor(core)) {
> > +        struct e1000_rx_desc *d = (struct e1000_rx_desc *) desc;
> > +        size_t offset = offsetof(struct e1000_rx_desc, status);
> > +        typeof(d->status) status = d->status;
> > +
> > +        d->status &= ~E1000_RXD_STAT_DD;
> > +        pci_dma_write(dev, addr, desc, len);
> > +
> > +        if (status & E1000_RXD_STAT_DD) {
> > +            d->status = status;
> > +            pci_dma_write(dev, addr + offset, &status, sizeof(status));
> > +        }
> > +    } else {
> > +        if (core->mac[RCTL] & E1000_RCTL_DTYP_PS) {
> > +            union e1000_rx_desc_packet_split *d =
> > +                (union e1000_rx_desc_packet_split *) desc;
> > +            size_t offset = offsetof(union e1000_rx_desc_packet_split,
> > +                wb.middle.status_error);
> > +            typeof(d->wb.middle.status_error) status =
> > +                d->wb.middle.status_error;
>
> Any reason to use typeof here? Its type is known to be uint32_t?

My intention was using exact type same with struct member status_error, 
which is indeed uint32_t now. If the type of status_error in struct be 
changed in some case, we do not need to change everywhere.

Maybe I worry too much, the struct is related to h/w spec, so it is 
unlikely be changed in the future.

Should I send v2 to use uint32_t directly? I'm also OK with it.

> > +
> > +            d->wb.middle.status_error &= ~E1000_RXD_STAT_DD;
> > +            pci_dma_write(dev, addr, desc, len);
> > +
> > +            if (status & E1000_RXD_STAT_DD) {
> > +                d->wb.middle.status_error = status;
> > +                pci_dma_write(dev, addr + offset, &status, sizeof(status));
> > +            }
> > +        } else {
> > +            union e1000_rx_desc_extended *d =
> > +                (union e1000_rx_desc_extended *) desc;
> > +            size_t offset = offsetof(union e1000_rx_desc_extended,
> > +                wb.upper.status_error);
> > +            typeof(d->wb.upper.status_error) status = d->wb.upper.status_error;
>
> So did here.
>
> Thanks
>
> > +
> > +            d->wb.upper.status_error &= ~E1000_RXD_STAT_DD;
> > +            pci_dma_write(dev, addr, desc, len);
> > +
> > +            if (status & E1000_RXD_STAT_DD) {
> > +                d->wb.upper.status_error = status;
> > +                pci_dma_write(dev, addr + offset, &status, sizeof(status));
> > +            }
> > +        }
> > +    }
> > +}
> > +
> >   typedef struct e1000e_ba_state_st {
> >       uint16_t written[MAX_PS_BUFFERS];
> >       uint8_t cur_idx;
> > @@ -1600,7 +1652,7 @@ e1000e_write_packet_to_guest(E1000ECore *core, struct 
> > NetRxPkt *pkt,
> >
> >           e1000e_write_rx_descr(core, desc, is_last ? core->rx_pkt : NULL,
> >                              rss_info, do_ps ? ps_hdr_len : 0, 
> > &bastate.written);
> > -        pci_dma_write(d, base, &desc, core->rx_desc_len);
> > +        e1000e_pci_dma_write_rx_desc(core, base, desc, core->rx_desc_len);
> >
> >           e1000e_ring_advance(core, rxi,
> >                               core->rx_desc_len / E1000_MIN_RX_DESC_LEN);
> > --
> > 2.17.1


--
Thanks,
- Ding Hui