On Mon, Nov 14, 2022 at 04:03:24PM -0800, Tony Nguyen wrote:
> From: Bartosz Staszewski <bartoszx.staszewski@xxxxxxxxx>
>
> The driver is currently logging an error message "MTU too large to enable XDP"
> when trying to enable XDP on totally normal MTU.
Could you rephrase this to "Fix the inability to attach XDP program on
downed interface" ?
>
> This was caused by whenever the interface was down, function
> i40e_xdp was passing vsi->rx_buf_len field to i40e_xdp_setup()
> which was equal 0. i40e_open() then calls i40e_vsi_configure_rx()
> which configures that field, but that only happens when interface is up.
> When it is down, i40e_open() is not being called, thus vsi->rx_buf_len
> which causes the bug is not set.
Where rx_buf_len is cleared though? Or is it only the case for a fresh
start?
>
> Solution for this is calculate buffer length in newly created
> function - i40e_calculate_vsi_rx_buf_len() that return actual buffer
> length. Buffer length is being calculated based on the same rules applied
> previously in i40e_vsi_configure_rx() function.
>
> Fixes: 613142b0bb88 ("i40e: Log error for oversized MTU on device")
I think the problem dates back to 2017 and:
Fixes: 0c8493d90b6b ("i40e: add XDP support for pass and drop actions")
CC: Bjorn Topel <bjorn@xxxxxxxxxx>
So i'm saying let's have two fixes tags here.
> Signed-off-by: Bartosz Staszewski <bartoszx.staszewski@xxxxxxxxx>
> Signed-off-by: Mateusz Palczewski <mateusz.palczewski@xxxxxxxxx>
> Tested-by: Shwetha Nagaraju <Shwetha.nagaraju@xxxxxxxxx>
> Signed-off-by: Tony Nguyen <anthony.l.nguyen@xxxxxxxxx>
> ---
> drivers/net/ethernet/intel/i40e/i40e_main.c | 42 +++++++++++++++------
> 1 file changed, 30 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_main.c b/drivers/net/ethernet/intel/i40e/i40e_main.c
> index 41112f92f9ef..4b3b6e5b612d 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_main.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_main.c
> @@ -3695,6 +3695,30 @@ static int i40e_vsi_configure_tx(struct i40e_vsi *vsi)
> return err;
> }
>
> +/**
> + * i40e_calculate_vsi_rx_buf_len - Calculates buffer length
> + *
> + * @vsi: VSI to calculate rx_buf_len from
> + */
> +static u16 i40e_calculate_vsi_rx_buf_len(struct i40e_vsi *vsi)
> +{
> + u16 ret;
> +
> + if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX)) {
> + ret = I40E_RXBUFFER_2048;
> +#if (PAGE_SIZE < 8192)
> + } else if (!I40E_2K_TOO_SMALL_WITH_PADDING &&
> + (vsi->netdev->mtu <= ETH_DATA_LEN)) {
> + ret = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
> +#endif
> + } else {
> + ret = (PAGE_SIZE < 8192) ? I40E_RXBUFFER_3072 :
> + I40E_RXBUFFER_2048;
> + }
> +
> + return ret;
> +}
> +
> /**
> * i40e_vsi_configure_rx - Configure the VSI for Rx
> * @vsi: the VSI being configured
> @@ -3706,20 +3730,14 @@ static int i40e_vsi_configure_rx(struct i40e_vsi *vsi)
> int err = 0;
> u16 i;
>
> - if (!vsi->netdev || (vsi->back->flags & I40E_FLAG_LEGACY_RX)) {
> - vsi->max_frame = I40E_MAX_RXBUFFER;
> - vsi->rx_buf_len = I40E_RXBUFFER_2048;
> + vsi->max_frame = I40E_MAX_RXBUFFER;
> + vsi->rx_buf_len = i40e_calculate_vsi_rx_buf_len(vsi);
> +
> #if (PAGE_SIZE < 8192)
> - } else if (!I40E_2K_TOO_SMALL_WITH_PADDING &&
> - (vsi->netdev->mtu <= ETH_DATA_LEN)) {
> + if (vsi->netdev && !I40E_2K_TOO_SMALL_WITH_PADDING &&
> + vsi->netdev->mtu <= ETH_DATA_LEN)
> vsi->max_frame = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
> - vsi->rx_buf_len = I40E_RXBUFFER_1536 - NET_IP_ALIGN;
> #endif
> - } else {
> - vsi->max_frame = I40E_MAX_RXBUFFER;
> - vsi->rx_buf_len = (PAGE_SIZE < 8192) ? I40E_RXBUFFER_3072 :
> - I40E_RXBUFFER_2048;
> - }
>
> /* set up individual rings */
> for (i = 0; i < vsi->num_queue_pairs && !err; i++)
> @@ -13267,7 +13285,7 @@ static int i40e_xdp_setup(struct i40e_vsi *vsi, struct bpf_prog *prog,
> int i;
>
> /* Don't allow frames that span over multiple buffers */
> - if (frame_size > vsi->rx_buf_len) {
> + if (frame_size > i40e_calculate_vsi_rx_buf_len(vsi)) {
> NL_SET_ERR_MSG_MOD(extack, "MTU too large to enable XDP");
> return -EINVAL;
> }
> --
> 2.35.1
>
