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Date:   Fri, 21 Aug 2020 16:20:34 -0700
From:   Nathan Chancellor <natechancellor@gmail.com>
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>, Eli Cohen <eli@mellanox.com>,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com
Subject: Re: [PATCH] vdpa/mlx5: Avoid warnings about shifts on 32-bit
 platforms
Message-ID: <20200821232034.GA1472930@ubuntu-n2-xlarge-x86>
References: <20200821225018.940798-1-natechancellor@gmail.com>
 <1975c0a0-c19a-c91e-dc10-2918061cc4e7@infradead.org>
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On Fri, Aug 21, 2020 at 04:13:19PM -0700, Randy Dunlap wrote:
> 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 <natechancellor@gmail.com>
> 
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> on 2020-AUG-10 for i386:
> https://lore.kernel.org/linux-next/5a7a0e6d-842a-78f6-aeac-c5b4c27b7186@infradead.org/
> :(

Sorry, I saw this in my own build tests and was not aware of the
previous report since I have not really been paying attention to
the mailing lists as of late :(

Should I need to do a v2, I will be sure to include that tag; otherwise,
it would be great if it could be picked up along with the below.

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

Thank you for testing!

> 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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