Re: [dpdk-dev] [PATCH] net/iavf: fix vector id assignment

["Yu, DapengX" <dapengx.yu@intel.com>]

Hi Ting,

The following test case is for i40e. if you want to test the case on ice, just ignore step 1. 

    Step1: switch i40evf to iavf
    # sed -i '/{ RTE_PCI_DEVICE(IAVF_INTEL_VENDOR_ID, IAVF_DEV_ID_ADAPTIVE_VF) },/a { RTE_PCI_DEVICE(IAVF_INTEL_VENDOR_ID, IAVF_DEV_ID_VF) },' drivers/net/iavf/iavf_ethdev.c
    # sed -i -e '/I40E_DEV_ID_VF/s/0x154C/0x164C/g'  drivers/net/i40e/base/i40e_devids.h
    # sed -i -e '/DEV_RX_OFFLOAD_CHECKSUM,/d' ./examples/l3fwd-power/main.c
    
    Step2. build dpdk and l3fwd-power
    
    Step3. create 1 vf
    # echo 1 > /sys/bus/pci/devices/0000\:81\:00.0/sriov_numvfs
    
    Step4. bind vf to vfio-pci
    # usertools/dpdk-devbind.py --force --bind=vfio-pci 81:02.0
    
    Step5. launch l3fwd-power
    # ./x86_64-native-linuxapp-gcc/examples/dpdk-l3fwd-power -l 0-1 -n 4 -- -P -p 0x1 --config='(0,0,0),(0,1,1)'

Expected result:
    start  l3fwd-power successfully
Actual result:
    fail to start l3fwd-power

-----Original Message-----
From: Xu, Ting 
Sent: Tuesday, January 12, 2021 2:27 PM
To: Yu, DapengX <dapengx.yu@intel.com>; Zhang, Qi Z <qi.z.zhang@intel.com>; Wu, Jingjing <jingjing.wu@intel.com>; Xing, Beilei <beilei.xing@intel.com>
Cc: dev@dpdk.org; Yu, DapengX <dapengx.yu@intel.com>; stable@dpdk.org
Subject: RE: [PATCH] net/iavf: fix vector id assignment

> -----Original Message-----
> From: dapengx.yu@intel.com <dapengx.yu@intel.com>
> Sent: Friday, January 8, 2021 6:21 PM
> To: Zhang, Qi Z <qi.z.zhang@intel.com>; Wu, Jingjing 
> <jingjing.wu@intel.com>; Xing, Beilei <beilei.xing@intel.com>; Xu, 
> Ting <ting.xu@intel.com>
> Cc: dev@dpdk.org; Yu, DapengX <dapengx.yu@intel.com>; stable@dpdk.org
> Subject: [PATCH] net/iavf: fix vector id assignment
> 
> From: YU DAPENG <dapengx.yu@intel.com>
> 
> The number of MSI-X interrupts on Rx shall be the minimal value of the 
> number of available MSI-X interrupts per VF - 1 (the 1 is for 
> miscellaneous
> interrupt) and the number of configured Rx queues.
> The current code break the rule because the number of available MSI-X 
> interrupts is used as the first value, but code does not subtract 1 from it.
> 
> In normal situation, the first value is larger than the second value. 
> So each queue can be assigned a unique vector_id.
> 
> For example: 17 available MSI-X interrupts, and 16 available Rx queues 
> per VF; but only 4 Rx queues are configured when device is started.
> vector_id:0 is for misc interrupt, vector_id:1 for Rx queue0,
> vector_id:2 for Rx queue1, vector_id:3 for Rx queue2, vector_id:4 for 
> Rx queue3.
> 
> Current code breaks the rule in this normal situation, because when 
> assign vector_ids to interrupt handle, for example, it does not assign
> vector_id:4 to the queue3, but assign vector_id:1 to it, because the 
> condition used causes vector_id wrap around too early.
> 

Hi, Dapeng,

Could you please further explain in which condition will this error happen? Seems it requires vf->nb_msix = 3 to make it happen, but I do not notice such situation.
I know it may be an example, is there any more specific case?

Thanks.

> In iavf_config_irq_map(), the current code does not write data into 
> the last element of vecmap[], because of the previous code break. 
> Which cause wrong data is sent to PF with opcode 
> VIRTCHNL_OP_CONFIG_IRQ_MAP and cause
> error: VIRTCHNL_STATUS_ERR_PARAM(-5).
> 
> If kernel driver supports large VFs (up to 256 queues), different 
> queues can be assigned same vector_id.
> 
> In order to adapt to large VFs and avoid wrapping early, the condition 
> is replaced from vec >= vf->nb_msix to vec >= vf->vf_res->max_vectors.
> 
> Fixes: d6bde6b5eae9 ("net/avf: enable Rx interrupt")
> Cc: stable@dpdk.org
> 
> Signed-off-by: YU DAPENG <dapengx.yu@intel.com>
> ---
>  drivers/net/iavf/iavf_ethdev.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/iavf/iavf_ethdev.c 
> b/drivers/net/iavf/iavf_ethdev.c index 7e3c26a94..d730bb156 100644
> --- a/drivers/net/iavf/iavf_ethdev.c
> +++ b/drivers/net/iavf/iavf_ethdev.c
> @@ -483,6 +483,7 @@ static int iavf_config_rx_queues_irqs(struct 
> rte_eth_dev *dev,  struct iavf_qv_map *qv_map;  uint16_t interval, i;  
> int vec;
> +uint16_t max_vectors;
> 
>  if (rte_intr_cap_multiple(intr_handle) &&
>      dev->data->dev_conf.intr_conf.rxq) { @@ -570,15 +571,16 @@ static 
> int iavf_config_rx_queues_irqs(struct rte_eth_dev *dev,
>  /* If Rx interrupt is reuquired, and we can use
>   * multi interrupts, then the vec is from 1
>   */
> -vf->nb_msix = RTE_MIN(vf->vf_res->max_vectors,
> -      intr_handle->nb_efd);
> +max_vectors =
> +vf->vf_res->max_vectors -
> IAVF_RX_VEC_START;
> +vf->nb_msix = RTE_MIN(max_vectors, intr_handle-
> >nb_efd);
>  vf->msix_base = IAVF_RX_VEC_START;
>  vec = IAVF_RX_VEC_START;
>  for (i = 0; i < dev->data->nb_rx_queues; i++) {  qv_map[i].queue_id = 
> i;  qv_map[i].vector_id = vec;  intr_handle->intr_vec[i] = vec++; -if 
> (vec >= vf->nb_msix)
> +if (vec >= vf->vf_res->max_vectors)
>  vec = IAVF_RX_VEC_START;
>  }
>  vf->qv_map = qv_map;
> --
> 2.27.0