[PATCH v2 1/1] drm/syncobj: add sideband payload
Koenig, Christian
Christian.Koenig at amd.com
Thu Aug 8 09:32:36 UTC 2019
Am 08.08.19 um 11:04 schrieb Lionel Landwerlin:
> 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)
>
> Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> Cc: Christian Koenig <Christian.Koenig at amd.com>
> Cc: Jason Ekstrand <jason at jlekstrand.net>
> Cc: David(ChunMing) Zhou <David1.Zhou at amd.com>
> ---
> drivers/gpu/drm/drm_internal.h | 2 ++
> drivers/gpu/drm/drm_ioctl.c | 3 ++
> drivers/gpu/drm/drm_syncobj.c | 63 +++++++++++++++++++++++++++++++---
> include/drm/drm_syncobj.h | 9 +++++
> include/uapi/drm/drm.h | 5 ++-
> 5 files changed, 77 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
> index 51a2055c8f18..de5267711a7c 100644
> --- a/drivers/gpu/drm/drm_internal.h
> +++ b/drivers/gpu/drm/drm_internal.h
> @@ -208,6 +208,8 @@ 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_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..7fd99533f78f 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -703,6 +703,9 @@ 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_SIDEBAND, drm_syncobj_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..66f4f91baa6d 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);
>
> @@ -1205,7 +1207,7 @@ drm_syncobj_timeline_signal_ioctl(struct drm_device *dev, void *data,
> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
> return -EOPNOTSUPP;
>
> - if (args->pad != 0)
> + if (args->flags != 0)
> return -EINVAL;
>
> if (args->count_handles == 0)
> @@ -1276,7 +1278,7 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
> if (!drm_core_check_feature(dev, DRIVER_SYNCOBJ_TIMELINE))
> return -EOPNOTSUPP;
>
> - if (args->pad != 0)
> + if (args->flags != 0)
> return -EINVAL;
>
> if (args->count_handles == 0)
> @@ -1312,15 +1314,68 @@ int drm_syncobj_query_ioctl(struct drm_device *dev, void *data,
> point = dma_fence_is_signaled(last_signaled) ?
> last_signaled->seqno :
> to_dma_fence_chain(last_signaled)->prev_seqno;
> - dma_fence_put(last_signaled);
> + dma_fence_put(last_signaled);
> } else {
> point = 0;
> }
> ret = copy_to_user(&points[i], &point, sizeof(uint64_t));
> ret = ret ? -EFAULT : 0;
> if (ret)
> + goto error;
> + break;
> + }
> +
> +error:
> + drm_syncobj_array_free(syncobjs, args->count_handles);
> +
> + return ret;
> +}
Those changes above to drm_syncobj_query now look completely unrelated
to me.
> +
> +int drm_syncobj_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->flags != DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD &&
> + args->flags != DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD)
> + 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++) {
> + switch (args->flags) {
> + case DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD:
> + copy_to_user(&points[i], &syncobjs[i]->sideband_payload, sizeof(uint64_t));
> + ret = ret ? -EFAULT : 0;
> + if (ret)
> + goto error;
> + break;
> +
> + case DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD:
> + copy_from_user(&syncobjs[i]->sideband_payload, &points[i], sizeof(uint64_t));
> + ret = ret ? -EFAULT : 0;
> + if (ret)
> + goto error;
> break;
> + }
> }
> +
> +error:
> 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..dfcbaf603aff 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -782,7 +782,9 @@ struct drm_syncobj_timeline_array {
> __u64 handles;
> __u64 points;
> __u32 count_handles;
> - __u32 pad;
> + __u32 flags;
> +#define DRM_SYNCOBJ_TIMELINE_ARRAY_GET_SIDEBAND_PAYLOAD (0)
> +#define DRM_SYNCOBJ_TIMELINE_ARRAY_SET_SIDEBAND_PAYLOAD (1)
> };
>
>
> @@ -946,6 +948,7 @@ 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_SIDEBAND DRM_IOWR(0xCE, struct drm_syncobj_timeline_array)
Maybe better add separate get/set IOCTLs, but just a suggestion.
Regards,
Christian.
>
> /**
> * Device specific ioctls should only be in their respective headers
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