Re: [PATCH v3 1/1] drm/syncobj: add sideband payload

[Chunming Zhou <zhoucm1@amd.com>]

The propursal is fine with me.

one question:

how to wait sideband payload? Following patch will show that?

-David

在 2019/8/8 21:14, Lionel Landwerlin 写道:
> The Vulkan timeline semaphores allow signaling to happen on the point
> of the timeline without all of the its dependencies to be created.
>
> The current 2 implementations (AMD/Intel) of the Vulkan spec on top of
> the Linux kernel are using a thread to wait on the dependencies of a
> given point to materialize and delay actual submission to the kernel
> driver until the wait completes.
>
> If a binary semaphore is submitted for signaling along the side of a
> timeline semaphore waiting for completion that means that the drm
> syncobj associated with that binary semaphore will not have a DMA
> fence associated with it by the time vkQueueSubmit() returns. This and
> the fact that a binary semaphore can be signaled and unsignaled as
> before its DMA fences materialize mean that we cannot just rely on the
> fence within the syncobj but we also need a sideband payload verifying
> that the fence in the syncobj matches the last submission from the
> Vulkan API point of view.
>
> This change adds a sideband payload that is incremented with signaled
> syncobj when vkQueueSubmit() is called. The next vkQueueSubmit()
> waiting on a the syncobj will read the sideband payload and wait for a
> fence chain element with a seqno superior or equal to the sideband
> payload value to be added into the fence chain and use that fence to
> trigger the submission on the kernel driver.
>
> v2: Use a separate ioctl to get/set the sideband value (Christian)
>
> v3: Use 2 ioctls for get/set (Christian)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> Cc: Christian Koenig <Christian.Koenig@amd.com>
> Cc: Jason Ekstrand <jason@jlekstrand.net>
> Cc: David(ChunMing) Zhou <David1.Zhou@amd.com>
> ---
>   drivers/gpu/drm/drm_internal.h |  4 ++
>   drivers/gpu/drm/drm_ioctl.c    |  5 +++
>   drivers/gpu/drm/drm_syncobj.c  | 79 +++++++++++++++++++++++++++++++++-
>   include/drm/drm_syncobj.h      |  9 ++++
>   include/uapi/drm/drm.h         |  2 +
>   5 files changed, 98 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index 51a2055c8f18..0c9736199df0 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -208,6 +208,10 @@ int drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
>   				      struct drm_file *file_private);
>   int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
>   			    struct drm_file *file_private);
> +int drm_syncobj_get_sideband_ioctl(struct drm_device *dev, void *data,
> +				   struct drm_file *file_private);
> +int drm_syncobj_set_sideband_ioctl(struct drm_device *dev, void *data,
> +				   struct drm_file *file_private);
>   
>   /* drm_framebuffer.c */
>   void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index f675a3bb2c88..48500bf62801 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -703,6 +703,11 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
>   		      DRM_RENDER_ALLOW),
>   	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_QUERY, drm_syncobj_query_ioctl,
>   		      DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_GET_SIDEBAND, drm_syncobj_get_sideband_ioctl,
> +		      DRM_RENDER_ALLOW),
> +	DRM_IOCTL_DEF(DRM_IOCTL_SYNCOBJ_SET_SIDEBAND, drm_syncobj_set_sideband_ioctl,
> +		      DRM_RENDER_ALLOW),
> +
>   	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_GET_SEQUENCE, drm_crtc_get_sequence_ioctl, 0),
>   	DRM_IOCTL_DEF(DRM_IOCTL_CRTC_QUEUE_SEQUENCE, drm_crtc_queue_sequence_ioctl, 0),
>   	DRM_IOCTL_DEF(DRM_IOCTL_MODE_CREATE_LEASE, drm_mode_create_lease_ioctl, DRM_MASTER),
> diff --git a/drivers/gpu/drm/drm_syncobj.c b/drivers/gpu/drm/drm_syncobj.c
> index b927e482e554..c90ef20b9242 100644
> --- a/drivers/gpu/drm/drm_syncobj.c
> +++ b/drivers/gpu/drm/drm_syncobj.c
> @@ -1150,8 +1150,10 @@ drm_syncobj_reset_ioctl(struct drm_device *dev, void *data,
>   	if (ret < 0)
>   		return ret;
>   
> -	for (i = 0; i < args->count_handles; i++)
> +	for (i = 0; i < args->count_handles; i++) {
>   		drm_syncobj_replace_fence(syncobjs[i], NULL);
> +		syncobjs[i]->sideband_payload = 0;
> +	}
>   
>   	drm_syncobj_array_free(syncobjs, args->count_handles);
>   
> @@ -1321,6 +1323,81 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
>   		if (ret)
>   			break;
>   	}
> +
> +	drm_syncobj_array_free(syncobjs, args->count_handles);
> +
> +	return ret;
> +}
> +
> +int drm_syncobj_get_sideband_ioctl(struct drm_device *dev, void *data,
> +				   struct drm_file *file_private)
> +{
> +	struct drm_syncobj_timeline_array *args = data;
> +	struct drm_syncobj **syncobjs;
> +	uint64_t __user *points = u64_to_user_ptr(args->points);
> +	uint32_t i;
> +	int ret;
> +
> +	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
> +		return -EOPNOTSUPP;
> +
> +	if (args->pad != 0)
> +		return -EINVAL;
> +
> +	if (args->count_handles == 0)
> +		return -EINVAL;
> +
> +	ret = drm_syncobj_array_find(file_private,
> +				     u64_to_user_ptr(args->handles),
> +				     args->count_handles,
> +				     &syncobjs);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < args->count_handles; i++) {
> +		copy_to_user(&points[i], &syncobjs[i]->sideband_payload, sizeof(uint64_t));
> +		ret = ret ? -EFAULT : 0;
> +		if (ret)
> +			break;
> +	}
> +
> +	drm_syncobj_array_free(syncobjs, args->count_handles);
> +
> +	return ret;
> +}
> +
> +int drm_syncobj_set_sideband_ioctl(struct drm_device *dev, void *data,
> +				   struct drm_file *file_private)
> +{
> +	struct drm_syncobj_timeline_array *args = data;
> +	struct drm_syncobj **syncobjs;
> +	uint64_t __user *points = u64_to_user_ptr(args->points);
> +	uint32_t i;
> +	int ret;
> +
> +	if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
> +		return -EOPNOTSUPP;
> +
> +	if (args->pad != 0)
> +		return -EINVAL;
> +
> +	if (args->count_handles == 0)
> +		return -EINVAL;
> +
> +	ret = drm_syncobj_array_find(file_private,
> +				     u64_to_user_ptr(args->handles),
> +				     args->count_handles,
> +				     &syncobjs);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < args->count_handles; i++) {
> +		copy_from_user(&syncobjs[i]->sideband_payload, &points[i], sizeof(uint64_t));
> +		ret = ret ? -EFAULT : 0;
> +		if (ret)
> +			break;
> +	}
> +
>   	drm_syncobj_array_free(syncobjs, args->count_handles);
>   
>   	return ret;
> diff --git a/include/drm/drm_syncobj.h b/include/drm/drm_syncobj.h
> index 6cf7243a1dc5..b587b8e07547 100644
> --- a/include/drm/drm_syncobj.h
> +++ b/include/drm/drm_syncobj.h
> @@ -61,6 +61,15 @@ struct drm_syncobj {
>   	 * @file: A file backing for this syncobj.
>   	 */
>   	struct file *file;
> +	/**
> +	 * @sideband_payload: A 64bit side band payload.
> +	 *
> +	 * We use the sideband payload value to wait on binary syncobj fences
> +	 * to materialize. It is a reservation mechanism for the signaler to
> +	 * express that at some point in the future a dma fence with the same
> +	 * seqno will be put into the syncobj.
> +	 */
> +	u64 sideband_payload;
>   };
>   
>   void drm_syncobj_free(struct kref *kref);
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 8a5b2f8f8eb9..cffdc6c9772c 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -946,6 +946,8 @@ extern "C" {
>   #define DRM_IOCTL_SYNCOBJ_QUERY		DRM_IOWR(0xCB, struct drm_syncobj_timeline_array)
>   #define DRM_IOCTL_SYNCOBJ_TRANSFER	DRM_IOWR(0xCC, struct drm_syncobj_transfer)
>   #define DRM_IOCTL_SYNCOBJ_TIMELINE_SIGNAL	DRM_IOWR(0xCD, struct drm_syncobj_timeline_array)
> +#define DRM_IOCTL_SYNCOBJ_GET_SIDEBAND	DRM_IOR(0xCE, struct drm_syncobj_timeline_array)
> +#define DRM_IOCTL_SYNCOBJ_SET_SIDEBAND	DRM_IOWR(0xCF, struct drm_syncobj_timeline_array)
>   
>   /**
>    * Device specific ioctls should only be in their respective headers
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