Re: [PATCH v3 5/5] vhost-vdpa: add callback function for configure interrupt

[Jason Wang <jasowang@redhat.com>]

On 2021/1/26 下午3:42, Cindy Lu wrote:
> Add call back function for configure interrupt.
> Set the notifier's fd to the kernel driver when vdpa start.
> also set -1 while vdpa stop. then the kernel will release
> the related resource
>
> Signed-off-by: Cindy Lu <lulu@redhat.com>
> ---
>   hw/virtio/trace-events            |  2 ++
>   hw/virtio/vhost-vdpa.c            | 37 ++++++++++++++++++++++++++++++-
>   include/hw/virtio/vhost-backend.h |  4 ++++
>   3 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
> index 2060a144a2..6710835b46 100644
> --- a/hw/virtio/trace-events
> +++ b/hw/virtio/trace-events
> @@ -52,6 +52,8 @@ vhost_vdpa_set_vring_call(void *dev, unsigned int index, int fd) "dev: %p index:
>   vhost_vdpa_get_features(void *dev, uint64_t features) "dev: %p features: 0x%"PRIx64
>   vhost_vdpa_set_owner(void *dev) "dev: %p"
>   vhost_vdpa_vq_get_addr(void *dev, void *vq, uint64_t desc_user_addr, uint64_t avail_user_addr, uint64_t used_user_addr) "dev: %p vq: %p desc_user_addr: 0x%"PRIx64" avail_user_addr: 0x%"PRIx64" used_user_addr: 0x%"PRIx64
> +vhost_vdpa_set_config_call(void *dev, int *fd)"dev: %p fd: %p"
> +
>   
>   # virtio.c
>   virtqueue_alloc_element(void *elem, size_t sz, unsigned in_num, unsigned out_num) "elem %p size %zd in_num %u out_num %u"
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 01d2101d09..cc1d39d663 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -467,20 +467,47 @@ static int vhost_vdpa_get_config(struct vhost_dev *dev, uint8_t *config,
>       }
>       return ret;
>    }
> +static void vhost_vdpa_config_notify_start(struct vhost_dev *dev,
> +                                struct VirtIODevice *vdev, bool start)
> +{
> +    int fd, r;
> +    if (start) {
> +        fd = event_notifier_get_fd(&vdev->config_notifier);
> +        vdev->use_config_notifier = true;
> +     } else {
> +        fd = -1;
> +        vdev->use_config_notifier = false;
> +     }
> +     /*set the fd call back to vdpa driver*/


I guess checkpatch.pl might warn here. Please try to silent checkpath.pl 
before submitting patches.


> +    r = dev->vhost_ops->vhost_set_config_call(dev, &fd);
> +    if (r) {
> +        vdev->use_config_notifier = false;
> +        info_report("vhost_vdpa_config_notify not started!");


This looks kind of fragile. Do we need some workaround here like:

1) filter out the features that depends on config interrupt

or

2) A timer to watch the change of config space

Thanks


> +    }
> +    /*active the config_notifier when vdev->use_config_notifier is true*/
> +    if ((vdev->use_config_notifier) && (start)) {
> +        event_notifier_set(&vdev->config_notifier);
> +    }
> +    return;
>   
> +}
>   static int vhost_vdpa_dev_start(struct vhost_dev *dev, bool started)
>   {
>       struct vhost_vdpa *v = dev->opaque;
>       trace_vhost_vdpa_dev_start(dev, started);
> +    VirtIODevice *vdev = dev->vdev;
> +
>       if (started) {
>           uint8_t status = 0;
>           memory_listener_register(&v->listener, &address_space_memory);
>           vhost_vdpa_set_vring_ready(dev);
>           vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
>           vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &status);
> -
> +        /*set the configure interrupt call back*/
> +        vhost_vdpa_config_notify_start(dev, vdev, true);
>           return !(status & VIRTIO_CONFIG_S_DRIVER_OK);
>       } else {
> +        vhost_vdpa_config_notify_start(dev, vdev, false);
>           vhost_vdpa_reset_device(dev);
>           vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
>                                      VIRTIO_CONFIG_S_DRIVER);
> @@ -546,6 +573,13 @@ static int vhost_vdpa_set_vring_call(struct vhost_dev *dev,
>       return vhost_vdpa_call(dev, VHOST_SET_VRING_CALL, file);
>   }
>   
> +static int vhost_vdpa_set_config_call(struct vhost_dev *dev,
> +                                       int *fd)
> +{
> +    trace_vhost_vdpa_set_config_call(dev, fd);
> +    return vhost_vdpa_call(dev, VHOST_VDPA_SET_CONFIG_CALL, fd);
> +}
> +
>   static int vhost_vdpa_get_features(struct vhost_dev *dev,
>                                        uint64_t *features)
>   {
> @@ -611,4 +645,5 @@ const VhostOps vdpa_ops = {
>           .vhost_get_device_id = vhost_vdpa_get_device_id,
>           .vhost_vq_get_addr = vhost_vdpa_vq_get_addr,
>           .vhost_force_iommu = vhost_vdpa_force_iommu,
> +        .vhost_set_config_call = vhost_vdpa_set_config_call,
>   };
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index 8a6f8e2a7a..1a2fee8994 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -125,6 +125,9 @@ typedef int (*vhost_get_device_id_op)(struct vhost_dev *dev, uint32_t *dev_id);
>   
>   typedef bool (*vhost_force_iommu_op)(struct vhost_dev *dev);
>   
> +typedef int (*vhost_set_config_call_op)(struct vhost_dev *dev,
> +                                       int *fd);
> +
>   typedef struct VhostOps {
>       VhostBackendType backend_type;
>       vhost_backend_init vhost_backend_init;
> @@ -170,6 +173,7 @@ typedef struct VhostOps {
>       vhost_vq_get_addr_op  vhost_vq_get_addr;
>       vhost_get_device_id_op vhost_get_device_id;
>       vhost_force_iommu_op vhost_force_iommu;
> +    vhost_set_config_call_op vhost_set_config_call;
>   } VhostOps;
>   
>   extern const VhostOps user_ops;