Hi Liu/Mark/Stephen, I have tried to modify the code with all of your latest comments. Do let me know if this looks fine or you have more comments.
Changes done : -- max frame ize is compare to VIRTIO_MAX_RX_PKTLEN instead of dev_info.max_rx_pktlen -- removed the CRC_LEN from the ether_len calculation and added the merge rx buf hdr len. ether_hdr_len = ETHER_HDR_LEN + VLAN_TAG_SIZE + hw->vtnet_hdr_size -- Still retained the VLAN Size as the worst case scenario. -- drivers/net/virtio/virtio_ethdev.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c index 423c597..1dbfea6 100644 --- a/drivers/net/virtio/virtio_ethdev.c +++ b/drivers/net/virtio/virtio_ethdev.c @@ -653,12 +653,20 @@ virtio_dev_allmulticast_disable(struct rte_eth_dev *dev) PMD_INIT_LOG(ERR, "Failed to disable allmulticast"); } +#define VLAN_TAG_SIZE 4 /* 802.3ac tag (not DMA'd) */ + +static int virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu) +{ + struct virtio_hw *hw = dev->data->dev_private; + uint32_t ether_hdr_len = ETHER_HDR_LEN + VLAN_TAG_SIZE + hw->vtnet_hdr_size; + uint32_t frame_size = mtu + ether_hdr_len; + + if (mtu < ETHER_MIN_MTU || frame_size > VIRTIO_MAX_RX_PKTLEN ) { + PMD_INIT_LOG(ERR, "MTU should be between %d and %d\n", + ETHER_MIN_MTU, VIRTIO_MAX_RX_PKTLEN); + return -EINVAL; + } + return 0; +} /* * dev_ops for virtio, bare necessities for basic operation */ @@ -677,7 +685,6 @@ static const struct eth_dev_ops virtio_eth_dev_ops = { .allmulticast_enable = virtio_dev_allmulticast_enable, .allmulticast_disable = virtio_dev_allmulticast_disable, + .mtu_set = virtio_mtu_set, .dev_infos_get = virtio_dev_info_get, .stats_get = virtio_dev_stats_get, .xstats_get = virtio_dev_xstats_get, -- Please do let me know if this looks good to you all. Thanks -- Regards, Souvik -----Original Message----- From: Kavanagh, Mark B [mailto:mark.b.kavan...@intel.com] Sent: Friday, September 23, 2016 5:08 AM To: Yuanhan Liu <yuanhan.liu at linux.intel.com>; Stephen Hemminger <stephen at networkplumber.org> Cc: Dey, Souvik <sodey at sonusnet.com>; dev at dpdk.org Subject: RE: [PATCH v6] net/virtio: add set_mtu in virtio >Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio > >On Wed, Sep 21, 2016 at 06:45:05PM -0700, Stephen Hemminger wrote: >> On Thu, 22 Sep 2016 00:08:38 +0000 >> "Dey, Souvik" <sodey at sonusnet.com<mailto:sodey at sonusnet.com>> wrote: >> >> > Answers inline. >> > >> > -- >> > Regards, >> > Souvik >> > >> > -----Original Message----- >> > From: Stephen Hemminger [mailto:stephen at networkplumber.org] >> > Sent: Wednesday, September 21, 2016 7:22 PM >> > To: Dey, Souvik <sodey at sonusnet.com<mailto:sodey at sonusnet.com>> >> > Cc: mark.b.kavanagh at intel.com<mailto:mark.b.kavanagh at intel.com>; >> > yuanhan.liu at linux.intel.com<mailto:yuanhan.liu at linux.intel.com>; >> > dev at dpdk.org<mailto:dev at dpdk.org> >> > Subject: Re: [PATCH v6] net/virtio: add set_mtu in virtio >> > >> > On Wed, 21 Sep 2016 19:11:47 -0400 >> > Dey <sodey at sonusnet.com<mailto:sodey at sonusnet.com>> wrote: >> > >> > > >> > > + >> > > +#define VLAN_TAG_SIZE 4 /* 802.3ac tag (not DMA'd) */ >> > > + >> > > +static int virtio_mtu_set(struct rte_eth_dev *dev, uint16_t mtu) { >> > > + struct rte_eth_dev_info dev_info; >> > > + uint32_t ether_hdr_len = ETHER_HDR_LEN + ETHER_CRC_LEN + >> > > VLAN_TAG_SIZE; >> > > + uint32_t frame_size = mtu + ether_hdr_len; >> > > + >> > > + virtio_dev_info_get(dev, &dev_info); >> > > + >> > > + if (mtu < ETHER_MIN_MTU || frame_size > dev_info.max_rx_pktlen) { >> > > + PMD_INIT_LOG(ERR, "MTU should be between %d and %d\n", >> > > + ETHER_MIN_MTU, >> > > + (dev_info.max_rx_pktlen - >> > > ether_hdr_len)); >> > > + return -EINVAL; >> > > + } >> > > + return 0; >> > > +} >> > >> > I am fine with the general idea of this patch but: >> > 1. Calling virtio_dev_info_get is needlessly wasteful when all you want >> > is to access the max packet length. Since max_rx_pktlen is always >> > VIRTIO_MAX_RX_PKTLEN, please just use that. >> > [Dey, Souvik] I am using the virtio_dev_info_get as in future >> > can/may support the >max_rx_pktlen as a variable to be set by the application. This will >keep the changes future proof. As we need to support till 65535 instead of >9728 as the linux does. >> >> Fine, then just dereference hw->rx_max_pktlen. Driver code can/should >> reference its own data directly. > >Dey, maybe you could just use VIRTIO_MAX_RX_PKTLEN here, like what you >did in early versions. > >> > >> > 2. Defining VLAN_TAG_SIZE is irrelevant if doing vlan offload. >> > [Dey, Souvik] vlan offload is not mandatory. Se again still have >> > vlan being sent up to >the application. In that case we need to consider the vlan length in the >Ethernet size. >> >> The code needs to handle both vlan offload (or not), correctly. You >> are assuming the worst case here. > >I think we are fine here to assume worst case. > >> > >> > 3. Virtio doesn't insert CRC, therefore CRC_LEN is irrelevant >> > [Dey, Souvik] I am not sure of this. Mark commented earlier to consider >> > this length too. >Mark what do you suggest ? >> >> Actually, the thing that matters is the size of the merge rx buf header, not >> the CRC. > >Right. My comments were based on my experience with DPDK ethdev PMDs - Stephen and Yuanhan have much more experience with virtio, so I'd go with their suggestion. > > --yliu >> >> The patch is still buggy. >>