Re: [dpdk-dev] [PATCH] net/virtio: set offload flag for jumbo frames

[Jens Freimann <jfreimann@redhat.com>]

On Wed, Jan 30, 2019 at 04:41:55PM +0100, Maxime Coquelin wrote:
>
>
>On 1/30/19 4:26 PM, Jens Freimann wrote:
>>Port configuration fails when offload flags don't match the expected
>>value, e.g. when max-pkt-len is set to a value that should enable
>>receive port offloading but doesn't.
>>
>>This can be triggered by running testpmd e.g. with --max-pkt-len=2000.
>>It will fail with "Ethdev port_id=0 requested Rx offloads 0x800 doesn't
>>match Rx offloads capabilities 0x20d in rte_eth_dev_configure()"
>>
>>To fix this there are two cases to consider:
>>
>>1. VIRTIO_NET_F_MTU is negotiated. Then we need to check if the
>>    requested max. packet length fits into the MTU. If yes we set the
>>    offload flag.
>>2. VIRTIO_NET_F_MTU is not negotiated. We can set the offload flag.
>
>I think we need to Cc: stable and point to the commit introducing the
>regression. I think it is the one introducing the use of
>DEV_RX_OFFLOAD_JUMBO_FRAME in Virtio PMD.

ok

>>
>>Signed-off-by: Jens Freimann <jfreimann@redhat.com>
>>---
>>  drivers/net/virtio/virtio_ethdev.c | 11 +++++++++++
>>  1 file changed, 11 insertions(+)
>>
>>diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
>>index 7c4c1df00..e0d6542d4 100644
>>--- a/drivers/net/virtio/virtio_ethdev.c
>>+++ b/drivers/net/virtio/virtio_ethdev.c
>>@@ -2351,6 +2351,17 @@ virtio_dev_info_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
>>  	if ((host_features & tso_mask) == tso_mask)
>>  		dev_info->rx_offload_capa |= DEV_RX_OFFLOAD_TCP_LRO;
>>+	if (host_features & (1ULL << VIRTIO_NET_F_MTU)) {
>>+		struct virtio_net_config config;
>>+		vtpci_read_dev_config(hw,
>>+				offsetof(struct virtio_net_config, mtu),
>>+				&config.mtu, sizeof(config.mtu));
>>+		if (dev->data->dev_conf.rxmode.max_rx_pkt_len <= config.mtu)
>
>That is not exactly right, MTU does not take into account the Ethernet
>header, the VLAN tag and the virtio-net header.
>
>See virtio_mtu_set() for example.

I wasn't sure about it, will send a v2. Thanks for the review!

regards,
Jens