On Fri, Jul 01, 2022 at 09:28:21PM +0800, Zhu Lingshan wrote:
> ifcvf_get_config_size() should return a virtio device type specific value,
> however the ret_value should not be greater than the onboard size of
> the device implementation. E.g., for virtio_net, config_size should be
> the minimum value of sizeof(struct virtio_net_config) and the onboard
> cap size.
> 
> Signed-off-by: Zhu Lingshan <[email protected]>
> ---
>  drivers/vdpa/ifcvf/ifcvf_base.c | 13 +++++++++++--
>  drivers/vdpa/ifcvf/ifcvf_base.h |  2 ++
>  2 files changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
> index 48c4dadb0c7c..fb957b57941e 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.c
> @@ -128,6 +128,7 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev 
> *pdev)
>                       break;
>               case VIRTIO_PCI_CAP_DEVICE_CFG:
>                       hw->dev_cfg = get_cap_addr(hw, &cap);
> +                     hw->cap_dev_config_size = le32_to_cpu(cap.length);
>                       IFCVF_DBG(pdev, "hw->dev_cfg = %p\n", hw->dev_cfg);
>                       break;
>               }
> @@ -233,15 +234,23 @@ int ifcvf_verify_min_features(struct ifcvf_hw *hw, u64 
> features)
>  u32 ifcvf_get_config_size(struct ifcvf_hw *hw)
>  {
>       struct ifcvf_adapter *adapter;
> +     u32 net_config_size = sizeof(struct virtio_net_config);
> +     u32 blk_config_size = sizeof(struct virtio_blk_config);
> +     u32 cap_size = hw->cap_dev_config_size;
>       u32 config_size;
>  
>       adapter = vf_to_adapter(hw);
> +     /* If the onboard device config space size is greater than
> +      * the size of struct virtio_net/blk_config, only the spec
> +      * implementing contents size is returned, this is very
> +      * unlikely, defensive programming.
> +      */
>       switch (hw->dev_type) {
>       case VIRTIO_ID_NET:
> -             config_size = sizeof(struct virtio_net_config);
> +             config_size = cap_size >= net_config_size ? net_config_size : 
> cap_size;
>               break;
>       case VIRTIO_ID_BLOCK:
> -             config_size = sizeof(struct virtio_blk_config);
> +             config_size = cap_size >= blk_config_size ? blk_config_size : 
> cap_size;
>               break;
>       default:
>               config_size = 0;

There's a min macro for this.

> diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
> index 115b61f4924b..f5563f665cc6 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_base.h
> +++ b/drivers/vdpa/ifcvf/ifcvf_base.h
> @@ -87,6 +87,8 @@ struct ifcvf_hw {
>       int config_irq;
>       int vqs_reused_irq;
>       u16 nr_vring;
> +     /* VIRTIO_PCI_CAP_DEVICE_CFG size */
> +     u32 cap_dev_config_size;
>  };
>  
>  struct ifcvf_adapter {
> -- 
> 2.31.1

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