Then you need something that is functional equivalent to virtio PCI
which is actually the concept of vDPA (e.g vDPA provides
alternatives if
the queue_sel is hard in the EP implementation).
Okay, I just tried to compare the 'struct vdpa_config_ops' and 'struct
vhost_config_ops' ( introduced in [RFC PATCH 03/22] vhost: Add ops for
the VHOST driver to configure VHOST device).
struct vdpa_config_ops {
/* Virtqueue ops */
int (*set_vq_address)(struct vdpa_device *vdev,
u16 idx, u64 desc_area, u64 driver_area,
u64 device_area);
void (*set_vq_num)(struct vdpa_device *vdev, u16 idx, u32 num);
void (*kick_vq)(struct vdpa_device *vdev, u16 idx);
void (*set_vq_cb)(struct vdpa_device *vdev, u16 idx,
struct vdpa_callback *cb);
void (*set_vq_ready)(struct vdpa_device *vdev, u16 idx, bool
ready);
bool (*get_vq_ready)(struct vdpa_device *vdev, u16 idx);
int (*set_vq_state)(struct vdpa_device *vdev, u16 idx,
const struct vdpa_vq_state *state);
int (*get_vq_state)(struct vdpa_device *vdev, u16 idx,
struct vdpa_vq_state *state);
struct vdpa_notification_area
(*get_vq_notification)(struct vdpa_device *vdev, u16 idx);
/* vq irq is not expected to be changed once DRIVER_OK is set */
int (*get_vq_irq)(struct vdpa_device *vdv, u16 idx);
/* Device ops */
u32 (*get_vq_align)(struct vdpa_device *vdev);
u64 (*get_features)(struct vdpa_device *vdev);
int (*set_features)(struct vdpa_device *vdev, u64 features);
void (*set_config_cb)(struct vdpa_device *vdev,
struct vdpa_callback *cb);
u16 (*get_vq_num_max)(struct vdpa_device *vdev);
u32 (*get_device_id)(struct vdpa_device *vdev);
u32 (*get_vendor_id)(struct vdpa_device *vdev);
u8 (*get_status)(struct vdpa_device *vdev);
void (*set_status)(struct vdpa_device *vdev, u8 status);
void (*get_config)(struct vdpa_device *vdev, unsigned int offset,
void *buf, unsigned int len);
void (*set_config)(struct vdpa_device *vdev, unsigned int offset,
const void *buf, unsigned int len);
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);
/* Free device resources */
void (*free)(struct vdpa_device *vdev);
};
+struct vhost_config_ops {
+ int (*create_vqs)(struct vhost_dev *vdev, unsigned int nvqs,
+ unsigned int num_bufs, struct vhost_virtqueue *vqs[],
+ vhost_vq_callback_t *callbacks[],
+ const char * const names[]);
+ void (*del_vqs)(struct vhost_dev *vdev);
+ int (*write)(struct vhost_dev *vdev, u64 vhost_dst, void *src,
int len);
+ int (*read)(struct vhost_dev *vdev, void *dst, u64 vhost_src, int
len);
+ int (*set_features)(struct vhost_dev *vdev, u64 device_features);
+ int (*set_status)(struct vhost_dev *vdev, u8 status);
+ u8 (*get_status)(struct vhost_dev *vdev);
+};
+
struct virtio_config_ops
I think there's some overlap here and some of the ops tries to do the
same thing.
I think it differs in (*set_vq_address)() and (*create_vqs)().
[create_vqs() introduced in struct vhost_config_ops provides
complimentary functionality to (*find_vqs)() in struct
virtio_config_ops. It seemingly encapsulates the functionality of
(*set_vq_address)(), (*set_vq_num)(), (*set_vq_cb)(),..].
Back to the difference between (*set_vq_address)() and (*create_vqs)(),
set_vq_address() directly provides the virtqueue address to the vdpa
device but create_vqs() only provides the parameters of the virtqueue
(like the number of virtqueues, number of buffers) but does not
directly
provide the address. IMO the backend client drivers (like net or vhost)
shouldn't/cannot by itself know how to access the vring created on
virtio front-end. The vdpa device/vhost device should have logic for
that. That will help the client drivers to work with different types of
vdpa device/vhost device and can access the vring created by virtio
irrespective of whether the vring can be accessed via mmio or kernel
space or user space.
I think vdpa always works with client drivers in userspace and
providing
userspace address for vring.
