On 8/21/20 3:50 PM, Nathan Chancellor wrote:
> Clang warns several times when building for 32-bit ARM along the lines
> of:
> 
> drivers/vdpa/mlx5/net/mlx5_vnet.c:1462:31: warning: shift count >= width
> of type [-Wshift-count-overflow]
>                 ndev->mvdev.mlx_features |= BIT(VIRTIO_F_VERSION_1);
>                                             ^~~~~~~~~~~~~~~~~~~~~~~
> 
> This is related to the BIT macro, which uses an unsigned long literal,
> which is 32-bit on ARM so having a shift equal to or larger than 32 will
> cause this warning, such as the above, where VIRTIO_F_VERSION_1 is 32.
> To avoid this, use BIT_ULL, which will be an unsigned long long. This
> matches the size of the features field throughout this driver, which is
> u64 so there should be no functional change.
> 
> Fixes: 1a86b377aa21 ("vdpa/mlx5: Add VDPA driver for supported mlx5 devices")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1140
> Signed-off-by: Nathan Chancellor <natechancel...@gmail.com>

Reported-by: Randy Dunlap <rdun...@infradead.org>
on 2020-AUG-10 for i386:
https://lore.kernel.org/linux-next/5a7a0e6d-842a-78f6-aeac-c5b4c27b7...@infradead.org/
:(

Acked-by: Randy Dunlap <rdun...@infradead.org> # build-tested

Thanks.

> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 50 +++++++++++++++----------------
>  1 file changed, 25 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c 
> b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 9df69d5efe8c..70676a6d1691 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -16,19 +16,19 @@
>  #define to_mvdev(__vdev) container_of((__vdev), struct mlx5_vdpa_dev, vdev)
>  
>  #define VALID_FEATURES_MASK                                                  
>                       \
> -     (BIT(VIRTIO_NET_F_CSUM) | BIT(VIRTIO_NET_F_GUEST_CSUM) |                
>                    \
> -      BIT(VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) | BIT(VIRTIO_NET_F_MTU) | 
> BIT(VIRTIO_NET_F_MAC) |   \
> -      BIT(VIRTIO_NET_F_GUEST_TSO4) | BIT(VIRTIO_NET_F_GUEST_TSO6) |          
>                    \
> -      BIT(VIRTIO_NET_F_GUEST_ECN) | BIT(VIRTIO_NET_F_GUEST_UFO) | 
> BIT(VIRTIO_NET_F_HOST_TSO4) | \
> -      BIT(VIRTIO_NET_F_HOST_TSO6) | BIT(VIRTIO_NET_F_HOST_ECN) | 
> BIT(VIRTIO_NET_F_HOST_UFO) |   \
> -      BIT(VIRTIO_NET_F_MRG_RXBUF) | BIT(VIRTIO_NET_F_STATUS) | 
> BIT(VIRTIO_NET_F_CTRL_VQ) |      \
> -      BIT(VIRTIO_NET_F_CTRL_RX) | BIT(VIRTIO_NET_F_CTRL_VLAN) |              
>                    \
> -      BIT(VIRTIO_NET_F_CTRL_RX_EXTRA) | BIT(VIRTIO_NET_F_GUEST_ANNOUNCE) |   
>                    \
> -      BIT(VIRTIO_NET_F_MQ) | BIT(VIRTIO_NET_F_CTRL_MAC_ADDR) | 
> BIT(VIRTIO_NET_F_HASH_REPORT) |  \
> -      BIT(VIRTIO_NET_F_RSS) | BIT(VIRTIO_NET_F_RSC_EXT) | 
> BIT(VIRTIO_NET_F_STANDBY) |           \
> -      BIT(VIRTIO_NET_F_SPEED_DUPLEX) | BIT(VIRTIO_F_NOTIFY_ON_EMPTY) |       
>                    \
> -      BIT(VIRTIO_F_ANY_LAYOUT) | BIT(VIRTIO_F_VERSION_1) | 
> BIT(VIRTIO_F_ACCESS_PLATFORM) |      \
> -      BIT(VIRTIO_F_RING_PACKED) | BIT(VIRTIO_F_ORDER_PLATFORM) | 
> BIT(VIRTIO_F_SR_IOV))
> +     (BIT_ULL(VIRTIO_NET_F_CSUM) | BIT_ULL(VIRTIO_NET_F_GUEST_CSUM) |        
>                            \
> +      BIT_ULL(VIRTIO_NET_F_CTRL_GUEST_OFFLOADS) | BIT_ULL(VIRTIO_NET_F_MTU) 
> | BIT_ULL(VIRTIO_NET_F_MAC) |   \
> +      BIT_ULL(VIRTIO_NET_F_GUEST_TSO4) | BIT_ULL(VIRTIO_NET_F_GUEST_TSO6) |  
>                            \
> +      BIT_ULL(VIRTIO_NET_F_GUEST_ECN) | BIT_ULL(VIRTIO_NET_F_GUEST_UFO) | 
> BIT_ULL(VIRTIO_NET_F_HOST_TSO4) | \
> +      BIT_ULL(VIRTIO_NET_F_HOST_TSO6) | BIT_ULL(VIRTIO_NET_F_HOST_ECN) | 
> BIT_ULL(VIRTIO_NET_F_HOST_UFO) |   \
> +      BIT_ULL(VIRTIO_NET_F_MRG_RXBUF) | BIT_ULL(VIRTIO_NET_F_STATUS) | 
> BIT_ULL(VIRTIO_NET_F_CTRL_VQ) |      \
> +      BIT_ULL(VIRTIO_NET_F_CTRL_RX) | BIT_ULL(VIRTIO_NET_F_CTRL_VLAN) |      
>                            \
> +      BIT_ULL(VIRTIO_NET_F_CTRL_RX_EXTRA) | 
> BIT_ULL(VIRTIO_NET_F_GUEST_ANNOUNCE) |                      \
> +      BIT_ULL(VIRTIO_NET_F_MQ) | BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR) | 
> BIT_ULL(VIRTIO_NET_F_HASH_REPORT) |  \
> +      BIT_ULL(VIRTIO_NET_F_RSS) | BIT_ULL(VIRTIO_NET_F_RSC_EXT) | 
> BIT_ULL(VIRTIO_NET_F_STANDBY) |           \
> +      BIT_ULL(VIRTIO_NET_F_SPEED_DUPLEX) | BIT_ULL(VIRTIO_F_NOTIFY_ON_EMPTY) 
> |                          \
> +      BIT_ULL(VIRTIO_F_ANY_LAYOUT) | BIT_ULL(VIRTIO_F_VERSION_1) | 
> BIT_ULL(VIRTIO_F_ACCESS_PLATFORM) |      \
> +      BIT_ULL(VIRTIO_F_RING_PACKED) | BIT_ULL(VIRTIO_F_ORDER_PLATFORM) | 
> BIT_ULL(VIRTIO_F_SR_IOV))
>  
>  #define VALID_STATUS_MASK                                                    
>                       \
>       (VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER | 
> VIRTIO_CONFIG_S_DRIVER_OK |        \
> @@ -149,7 +149,7 @@ static bool mlx5_vdpa_debug;
>  
>  #define MLX5_LOG_VIO_FLAG(_feature)                                          
>                       \
>       do {                                                                    
>                    \
> -             if (features & BIT(_feature))                                   
>                    \
> +             if (features & BIT_ULL(_feature))                               
>                    \
>                       mlx5_vdpa_info(mvdev, "%s\n", #_feature);               
>                    \
>       } while (0)
>  
> @@ -750,10 +750,10 @@ static bool vq_is_tx(u16 idx)
>  
>  static u16 get_features_12_3(u64 features)
>  {
> -     return (!!(features & BIT(VIRTIO_NET_F_HOST_TSO4)) << 9) |
> -            (!!(features & BIT(VIRTIO_NET_F_HOST_TSO6)) << 8) |
> -            (!!(features & BIT(VIRTIO_NET_F_CSUM)) << 7) |
> -            (!!(features & BIT(VIRTIO_NET_F_GUEST_CSUM)) << 6);
> +     return (!!(features & BIT_ULL(VIRTIO_NET_F_HOST_TSO4)) << 9) |
> +            (!!(features & BIT_ULL(VIRTIO_NET_F_HOST_TSO6)) << 8) |
> +            (!!(features & BIT_ULL(VIRTIO_NET_F_CSUM)) << 7) |
> +            (!!(features & BIT_ULL(VIRTIO_NET_F_GUEST_CSUM)) << 6);
>  }
>  
>  static int create_virtqueue(struct mlx5_vdpa_net *ndev, struct 
> mlx5_vdpa_virtqueue *mvq)
> @@ -1439,13 +1439,13 @@ static u64 mlx_to_vritio_features(u16 dev_features)
>       u64 result = 0;
>  
>       if (dev_features & MLX5_VIRTIO_NET_F_GUEST_CSUM)
> -             result |= BIT(VIRTIO_NET_F_GUEST_CSUM);
> +             result |= BIT_ULL(VIRTIO_NET_F_GUEST_CSUM);
>       if (dev_features & MLX5_VIRTIO_NET_F_CSUM)
> -             result |= BIT(VIRTIO_NET_F_CSUM);
> +             result |= BIT_ULL(VIRTIO_NET_F_CSUM);
>       if (dev_features & MLX5_VIRTIO_NET_F_HOST_TSO6)
> -             result |= BIT(VIRTIO_NET_F_HOST_TSO6);
> +             result |= BIT_ULL(VIRTIO_NET_F_HOST_TSO6);
>       if (dev_features & MLX5_VIRTIO_NET_F_HOST_TSO4)
> -             result |= BIT(VIRTIO_NET_F_HOST_TSO4);
> +             result |= BIT_ULL(VIRTIO_NET_F_HOST_TSO4);
>  
>       return result;
>  }
> @@ -1459,15 +1459,15 @@ static u64 mlx5_vdpa_get_features(struct vdpa_device 
> *vdev)
>       dev_features = MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, 
> device_features_bits_mask);
>       ndev->mvdev.mlx_features = mlx_to_vritio_features(dev_features);
>       if (MLX5_CAP_DEV_VDPA_EMULATION(mvdev->mdev, virtio_version_1_0))
> -             ndev->mvdev.mlx_features |= BIT(VIRTIO_F_VERSION_1);
> -     ndev->mvdev.mlx_features |= BIT(VIRTIO_F_ACCESS_PLATFORM);
> +             ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_F_VERSION_1);
> +     ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_F_ACCESS_PLATFORM);
>       print_features(mvdev, ndev->mvdev.mlx_features, false);
>       return ndev->mvdev.mlx_features;
>  }
>  
>  static int verify_min_features(struct mlx5_vdpa_dev *mvdev, u64 features)
>  {
> -     if (!(features & BIT(VIRTIO_F_ACCESS_PLATFORM)))
> +     if (!(features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM)))
>               return -EOPNOTSUPP;
>  
>       return 0;
> 
> base-commit: 8a7c3213db068135e816a6a517157de6443290d6
> 


-- 
~Randy
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