On Fri, Aug 9, 2019 at 8:43 AM Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx> wrote:
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)
v4: Use a single new ioctl
v5: a bunch of blattant mistakes
Store payload atomically (Chris)
Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@xxxxxxxxx>
Cc: Christian Koenig <Christian.Koenig@xxxxxxx>
Cc: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
Cc: David(ChunMing) Zhou <David1.Zhou@xxxxxxx>
---
drivers/gpu/drm/drm_internal.h | 2 ++
drivers/gpu/drm/drm_ioctl.c | 3 ++
drivers/gpu/drm/drm_syncobj.c | 58 +++++++++++++++++++++++++++++++++-
include/drm/drm_syncobj.h | 9 ++++++
include/uapi/drm/drm.h | 17 ++++++++++
5 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 51a2055c8f18..e297dfd85019 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_binary_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..644d0bc800a4 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_BINARY, drm_syncobj_binary_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..d2d3a8d1374d 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);
+ atomic64_set(&syncobjs[i]->binary_payload, 0);
+ }
drm_syncobj_array_free(syncobjs, args->count_handles);
@@ -1321,6 +1323,60 @@ 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_binary_ioctl(struct drm_device *dev, void *data,
+ struct drm_file *file_private)
+{
+ struct drm_syncobj_binary_array *args = data;
+ struct drm_syncobj **syncobjs;
+ u32 __user *access_flags = u64_to_user_ptr(args->access_flags);
+ u64 __user *values = u64_to_user_ptr(args->values);
+ u32 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++) {
+ u32 flags;
+
+ if (get_user(flags, &access_flags[i])) {
+ ret = -EFAULT;
+ break;
+ }
+
+
+ if (flags & DRM_SYNCOBJ_BINARY_VALUE_READ) {
+ u64 value = atomic64_read(&syncobjs[i]->binary_payload);
+
+ if (put_user(value, &values[i])) {
+ ret = -EFAULT;
+ break;
+ }
+ }
+
+ if (flags & DRM_SYNCOBJ_BINARY_VALUE_INC)
+ atomic64_inc(&syncobjs[i]->binary_payload);
You go out of your way to use atomics but then don't bother to do the read and increment atomically. Maybe something like
u64 value = 0;
if (flags & DRM_SYNCOBJ_BINARY_VALUE_INC)
value = atomic64_inc(...);
else if (flags & DRM_SYNCOBJ_BINARY_VALUE_READ)
value = atomic64_read(...);
if (flags & DRM_SYNCOBJ_BINARY_VALUE_READ)
put_user(...)
--Jason
+ }
+
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..aa76cb3f9107 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;
+ /**
+ * @binary_payload: A 64bit payload for binary syncobjs.
+ *
+ * We use the 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.
+ */
+ atomic64_t binary_payload;
};
void drm_syncobj_free(struct kref *kref);
diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
index 8a5b2f8f8eb9..78a0a413b788 100644
--- a/include/uapi/drm/drm.h
+++ b/include/uapi/drm/drm.h
@@ -785,6 +785,22 @@ struct drm_syncobj_timeline_array {
__u32 pad;
};
+struct drm_syncobj_binary_array {
+ /* A pointer to an array of u32 syncobj handles. */
+ __u64 handles;
+ /* A pointer to an array of u32 access flags for each handle. */
+ __u64 access_flags;
+ /* The binary value of a syncobj is read before it is incremented. */
+#define DRM_SYNCOBJ_BINARY_VALUE_READ (1u << 0)
+#define DRM_SYNCOBJ_BINARY_VALUE_INC (1u << 1)
+ /* A pointer to an array of u64 values written to by the kernel if the
+ * handle is flagged for reading.
+ */
+ __u64 values;
+ /* The length of the 3 arrays above. */
+ __u32 count_handles;
+ __u32 pad;
+};
/* Query current scanout sequence number */
struct drm_crtc_get_sequence {
@@ -946,6 +962,7 @@ 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_BINARY DRM_IOWR(0xCE, struct drm_syncobj_binary_array)
/**
* Device specific ioctls should only be in their respective headers
--
2.23.0.rc1
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