Date:   Thu, 1 Oct 2020 16:23:31 +0300
From:   Eli Cohen <elic@...dia.com>
To:     Jason Wang <jasowang@...hat.com>
CC:     <mst@...hat.com>, <lulu@...hat.com>, <kvm@...r.kernel.org>,
        <virtualization@...ts.linux-foundation.org>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <rob.miller@...adcom.com>, <lingshan.zhu@...el.com>,
        <eperezma@...hat.com>, <hanand@...inx.com>,
        <mhabets@...arflare.com>, <eli@...lanox.com>,
        <amorenoz@...hat.com>, <maxime.coquelin@...hat.com>,
        <stefanha@...hat.com>, <sgarzare@...hat.com>
Subject: Re: [RFC PATCH 09/24] vdpa: multiple address spaces support

On Thu, Sep 24, 2020 at 11:21:10AM +0800, Jason Wang wrote:
> This patches introduces the multiple address spaces support for vDPA
> device. This idea is to identify a specific address space via an
> dedicated identifier - ASID.
> 
> During vDPA device allocation, vDPA device driver needs to report the
> number of address spaces supported by the device then the DMA mapping
> ops of the vDPA device needs to be extended to support ASID.
> 
> This helps to isolate the DMA among the virtqueues. E.g in the case of
> virtio-net, the control virtqueue will not be assigned directly to
> guest.
> 
> This RFC patch only converts for the device that wants its own
> IOMMU/DMA translation logic. So it will rejects the device with more
> that 1 address space that depends on platform IOMMU. The plan to
> moving all the DMA mapping logic to the vDPA device driver instead of
> doing it in vhost-vDPA (otherwise it could result a very complicated
> APIs and actually vhost-vDPA doesn't care about how the actual
> composition/emulation were done in the device driver).
> 
> Signed-off-by: Jason Wang <jasowang@...hat.com>
> ---
>  drivers/vdpa/ifcvf/ifcvf_main.c   |  2 +-
>  drivers/vdpa/mlx5/net/mlx5_vnet.c |  5 +++--
>  drivers/vdpa/vdpa.c               |  4 +++-
>  drivers/vdpa/vdpa_sim/vdpa_sim.c  | 10 ++++++----
>  drivers/vhost/vdpa.c              | 14 +++++++++-----
>  include/linux/vdpa.h              | 23 ++++++++++++++++-------
>  6 files changed, 38 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index e6a0be374e51..86cdf5f8bcae 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -440,7 +440,7 @@ static int ifcvf_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  
>  	adapter = vdpa_alloc_device(struct ifcvf_adapter, vdpa,
>  				    dev, &ifc_vdpa_ops,
> -				    IFCVF_MAX_QUEUE_PAIRS * 2, 1);
> +				    IFCVF_MAX_QUEUE_PAIRS * 2, 1, 1);
>  
>  	if (adapter == NULL) {
>  		IFCVF_ERR(pdev, "Failed to allocate vDPA structure");
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 4e480f4f754e..db7404e121bf 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1788,7 +1788,8 @@ static u32 mlx5_vdpa_get_generation(struct vdpa_device *vdev)
>  	return mvdev->generation;
>  }
>  
> -static int mlx5_vdpa_set_map(struct vdpa_device *vdev, struct vhost_iotlb *iotlb)
> +static int mlx5_vdpa_set_map(struct vdpa_device *vdev, unsigned int asid,
> +			     struct vhost_iotlb *iotlb)
>  {
>  	struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
>  	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> @@ -1931,7 +1932,7 @@ void *mlx5_vdpa_add_dev(struct mlx5_core_dev *mdev)
>  	max_vqs = min_t(u32, max_vqs, MLX5_MAX_SUPPORTED_VQS);
>  
>  	ndev = vdpa_alloc_device(struct mlx5_vdpa_net, mvdev.vdev, mdev->device, &mlx5_vdpa_ops,
> -				 2 * mlx5_vdpa_max_qps(max_vqs), 1);
> +				 2 * mlx5_vdpa_max_qps(max_vqs), 1, 1);
>  	if (IS_ERR(ndev))
>  		return ndev;
>  
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 46399746ec7c..05195fa7865d 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -63,6 +63,7 @@ static void vdpa_release_dev(struct device *d)
>   * @config: the bus operations that is supported by this device
>   * @nvqs: number of virtqueues supported by this device
>   * @ngroups: number of groups supported by this device
> + * @nas: number of address spaces supported by this device
>   * @size: size of the parent structure that contains private data
>   *
>   * Driver should use vdpa_alloc_device() wrapper macro instead of
> @@ -74,7 +75,7 @@ static void vdpa_release_dev(struct device *d)
>  struct vdpa_device *__vdpa_alloc_device(struct device *parent,
>  					const struct vdpa_config_ops *config,
>  					int nvqs, unsigned int ngroups,
> -					size_t size)
> +					unsigned int nas, size_t size)
>  {
>  	struct vdpa_device *vdev;
>  	int err = -EINVAL;
> @@ -102,6 +103,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
>  	vdev->features_valid = false;
>  	vdev->nvqs = nvqs;
>  	vdev->ngroups = ngroups;
> +	vdev->nas = nas;
>  
>  	err = dev_set_name(&vdev->dev, "vdpa%u", vdev->index);
>  	if (err)
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index 6669c561bc6e..5dc04ec271bb 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> @@ -354,7 +354,7 @@ static struct vdpasim *vdpasim_create(void)
>  		ops = &vdpasim_net_config_ops;
>  
>  	vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops,
> -				    VDPASIM_VQ_NUM, 1);
> +				    VDPASIM_VQ_NUM, 1, 1);
>  	if (!vdpasim)
>  		goto err_alloc;
>  
> @@ -581,7 +581,7 @@ static u32 vdpasim_get_generation(struct vdpa_device *vdpa)
>  	return vdpasim->generation;
>  }
>  
> -static int vdpasim_set_map(struct vdpa_device *vdpa,
> +static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid,
>  			   struct vhost_iotlb *iotlb)
>  {
>  	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> @@ -608,7 +608,8 @@ static int vdpasim_set_map(struct vdpa_device *vdpa,
>  	return ret;
>  }
>  
> -static int vdpasim_dma_map(struct vdpa_device *vdpa, u64 iova, u64 size,
> +static int vdpasim_dma_map(struct vdpa_device *vdpa, unsigned int asid,
> +			   u64 iova, u64 size,
>  			   u64 pa, u32 perm)
>  {
>  	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> @@ -622,7 +623,8 @@ static int vdpasim_dma_map(struct vdpa_device *vdpa, u64 iova, u64 size,
>  	return ret;
>  }
>  
> -static int vdpasim_dma_unmap(struct vdpa_device *vdpa, u64 iova, u64 size)
> +static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
> +			     u64 iova, u64 size)
>  {
>  	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>  
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index ec3c94f706c1..eeefcd971e3f 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -557,10 +557,10 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
>  		return r;
>  
>  	if (ops->dma_map) {
> -		r = ops->dma_map(vdpa, iova, size, pa, perm);
> +		r = ops->dma_map(vdpa, 0, iova, size, pa, perm);
>  	} else if (ops->set_map) {
>  		if (!v->in_batch)
> -			r = ops->set_map(vdpa, iotlb);
> +			r = ops->set_map(vdpa, 0, iotlb);
>  	} else {
>  		r = iommu_map(v->domain, iova, pa, size,
>  			      perm_to_iommu_flags(perm));
> @@ -579,10 +579,10 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v,
>  	vhost_vdpa_iotlb_unmap(v, iotlb, iova, iova + size - 1);
>  
>  	if (ops->dma_map) {
> -		ops->dma_unmap(vdpa, iova, size);
> +		ops->dma_unmap(vdpa, 0, iova, size);
>  	} else if (ops->set_map) {
>  		if (!v->in_batch)
> -			ops->set_map(vdpa, iotlb);
> +			ops->set_map(vdpa, 0, iotlb);
>  	} else {
>  		iommu_unmap(v->domain, iova, size);
>  	}
> @@ -700,7 +700,7 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
>  		break;
>  	case VHOST_IOTLB_BATCH_END:
>  		if (v->in_batch && ops->set_map)
> -			ops->set_map(vdpa, iotlb);
> +			ops->set_map(vdpa, 0, iotlb);
>  		v->in_batch = false;
>  		break;
>  	default:
> @@ -949,6 +949,10 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
>  	int minor;
>  	int r;
>  
> +	/* Only support 1 address space */
> +	if (vdpa->ngroups != 1)
> +		return -ENOTSUPP;

Checkpatch warning:  prefer EOPNOTSUPP

> +
>  	/* Currently, we only accept the network devices. */
>  	if (ops->get_device_id(vdpa) != VIRTIO_ID_NET)
>  		return -ENOTSUPP;
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index d829512efd27..1e1163daa352 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -43,6 +43,8 @@ struct vdpa_vq_state {
>   * @index: device index
>   * @features_valid: were features initialized? for legacy guests
>   * @nvqs: the number of virtqueues
> + * @ngroups: the number of virtqueue groups
> + * @nas: the number of address spaces
>   */
>  struct vdpa_device {
>  	struct device dev;
> @@ -52,6 +54,7 @@ struct vdpa_device {
>  	bool features_valid;
>  	int nvqs;
>  	unsigned int ngroups;
> +	unsigned int nas;
>  };
>  
>  /**
> @@ -161,6 +164,7 @@ struct vdpa_device {
>   *				Needed for device that using device
>   *				specific DMA translation (on-chip IOMMU)
>   *				@vdev: vdpa device
> + *				@asid: address space identifier
>   *				@iotlb: vhost memory mapping to be
>   *				used by the vDPA
>   *				Returns integer: success (0) or error (< 0)
> @@ -169,6 +173,7 @@ struct vdpa_device {
>   *				specific DMA translation (on-chip IOMMU)
>   *				and preferring incremental map.
>   *				@vdev: vdpa device
> + *				@asid: address space identifier
>   *				@iova: iova to be mapped
>   *				@size: size of the area
>   *				@pa: physical address for the map
> @@ -180,6 +185,7 @@ struct vdpa_device {
>   *				specific DMA translation (on-chip IOMMU)
>   *				and preferring incremental unmap.
>   *				@vdev: vdpa device
> + *				@asid: address space identifier
>   *				@iova: iova to be unmapped
>   *				@size: size of the area
>   *				Returns integer: success (0) or error (< 0)
> @@ -225,10 +231,12 @@ struct vdpa_config_ops {
>  	u32 (*get_generation)(struct vdpa_device *vdev);
>  
>  	/* DMA ops */
> -	int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);
> -	int (*dma_map)(struct vdpa_device *vdev, u64 iova, u64 size,
> -		       u64 pa, u32 perm);
> -	int (*dma_unmap)(struct vdpa_device *vdev, u64 iova, u64 size);
> +	int (*set_map)(struct vdpa_device *vdev, unsigned int asid,
> +		       struct vhost_iotlb *iotlb);
> +	int (*dma_map)(struct vdpa_device *vdev, unsigned int asid,
> +		       u64 iova, u64 size, u64 pa, u32 perm);
> +	int (*dma_unmap)(struct vdpa_device *vdev, unsigned int asid,
> +			 u64 iova, u64 size);
>  
>  	/* Free device resources */
>  	void (*free)(struct vdpa_device *vdev);
> @@ -237,11 +245,12 @@ struct vdpa_config_ops {
>  struct vdpa_device *__vdpa_alloc_device(struct device *parent,
>  					const struct vdpa_config_ops *config,
>  					int nvqs, unsigned int ngroups,
> -					size_t size);
> +					unsigned int nas, size_t size);
>  
> -#define vdpa_alloc_device(dev_struct, member, parent, config, nvqs, ngroups) \
> +#define vdpa_alloc_device(dev_struct, member, parent, config, nvqs, \
> +			  ngroups, nas)				    \
>  			  container_of(__vdpa_alloc_device( \
> -				       parent, config, nvqs, ngroups, \
> +				       parent, config, nvqs, ngroups, nas,  \
>  				       sizeof(dev_struct) + \
>  				       BUILD_BUG_ON_ZERO(offsetof( \
>  				       dev_struct, member))), \
> -- 
> 2.20.1
> 

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