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

[Jason Wang]

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?

> +
> +            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
>