[PATCH v2 1/1] drm/syncobj: add sideband payload
Lionel Landwerlin
lionel.g.landwerlin at intel.com
Thu Aug 8 09:42:58 UTC 2019
On 08/08/2019 12:32, Koenig, Christian wrote:
> 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);
Whoops, I need to drop this.
>> } 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.
The diff is really weird indeed but apart from the mistake above it's right.
>
>> +
>> +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.
Alright, I was worried about polluting the ioctl IDs.
Did the new tests on the CTS helped reproduce on your side the issue
this is solving?
Thanks,
-Lionel
>
>>
>> /**
>> * Device specific ioctls should only be in their respective headers
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