drm/xe: Allow num_batch_buffer / num_binds == 0 in IOCTLs

The idea being out-syncs can signal indicating all previous operations
on the bind queue are complete. An example use case of this would be
support for implementing vkQueueWaitIdle easily.

All in-syncs are waited on before signaling out-syncs. This is
implemented by forming a composite software fence of in-syncs and
installing this fence in the out-syncs and exec queue last fence slot.

The last fence must be added as a dependency for jobs on user exec
queues as it is possible for the last fence to be a composite software
fence (unordered, ioctl with zero bb or binds) rather than hardware
fence (ordered, previous job on queue).

Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

1 files changed, 78 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
index 2a3f508722fc..e4c220cf9115 100644
--- a/drivers/gpu/drm/xe/xe_sync.c
+++ b/drivers/gpu/drm/xe/xe_sync.c
@@ -5,6 +5,7 @@
 
 #include "xe_sync.h"
 
+#include <linux/dma-fence-array.h>
 #include <linux/kthread.h>
 #include <linux/sched/mm.h>
 #include <linux/uaccess.h>
@@ -14,6 +15,7 @@
 #include <drm/xe_drm.h>
 
 #include "xe_device_types.h"
+#include "xe_exec_queue.h"
 #include "xe_macros.h"
 #include "xe_sched_job_types.h"
 
@@ -104,6 +106,7 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
 	int err;
 	bool exec = flags & SYNC_PARSE_FLAG_EXEC;
 	bool in_lr_mode = flags & SYNC_PARSE_FLAG_LR_MODE;
+	bool disallow_user_fence = flags & SYNC_PARSE_FLAG_DISALLOW_USER_FENCE;
 	bool signal;
 
 	if (copy_from_user(&sync_in, sync_user, sizeof(*sync_user)))
@@ -164,6 +167,9 @@ int xe_sync_entry_parse(struct xe_device *xe, struct xe_file *xef,
 		break;
 
 	case DRM_XE_SYNC_TYPE_USER_FENCE:
+		if (XE_IOCTL_DBG(xe, disallow_user_fence))
+			return -EOPNOTSUPP;
+
 		if (XE_IOCTL_DBG(xe, !signal))
 			return -EOPNOTSUPP;
 
@@ -264,3 +270,75 @@ void xe_sync_entry_cleanup(struct xe_sync_entry *sync)
 	if (sync->ufence)
 		user_fence_put(sync->ufence);
 }
+
+/**
+ * xe_sync_in_fence_get() - Get a fence from syncs, exec queue, and VM
+ * @sync: input syncs
+ * @num_sync: number of syncs
+ * @q: exec queue
+ * @vm: VM
+ *
+ * Get a fence from syncs, exec queue, and VM. If syncs contain in-fences create
+ * and return a composite fence of all in-fences + last fence. If no in-fences
+ * return last fence on  input exec queue. Caller must drop reference to
+ * returned fence.
+ *
+ * Return: fence on success, ERR_PTR(-ENOMEM) on failure
+ */
+struct dma_fence *
+xe_sync_in_fence_get(struct xe_sync_entry *sync, int num_sync,
+		     struct xe_exec_queue *q, struct xe_vm *vm)
+{
+	struct dma_fence **fences = NULL;
+	struct dma_fence_array *cf = NULL;
+	struct dma_fence *fence;
+	int i, num_in_fence = 0, current_fence = 0;
+
+	lockdep_assert_held(&vm->lock);
+
+	/* Count in-fences */
+	for (i = 0; i < num_sync; ++i) {
+		if (sync[i].fence) {
+			++num_in_fence;
+			fence = sync[i].fence;
+		}
+	}
+
+	/* Easy case... */
+	if (!num_in_fence) {
+		fence = xe_exec_queue_last_fence_get(q, vm);
+		dma_fence_get(fence);
+		return fence;
+	}
+
+	/* Create composite fence */
+	fences = kmalloc_array(num_in_fence + 1, sizeof(*fences), GFP_KERNEL);
+	if (!fences)
+		return ERR_PTR(-ENOMEM);
+	for (i = 0; i < num_sync; ++i) {
+		if (sync[i].fence) {
+			dma_fence_get(sync[i].fence);
+			fences[current_fence++] = sync[i].fence;
+		}
+	}
+	fences[current_fence++] = xe_exec_queue_last_fence_get(q, vm);
+	dma_fence_get(fences[current_fence - 1]);
+	cf = dma_fence_array_create(num_in_fence, fences,
+				    vm->composite_fence_ctx,
+				    vm->composite_fence_seqno++,
+				    false);
+	if (!cf) {
+		--vm->composite_fence_seqno;
+		goto err_out;
+	}
+
+	return &cf->base;
+
+err_out:
+	while (current_fence)
+		dma_fence_put(fences[--current_fence]);
+	kfree(fences);
+	kfree(cf);
+
+	return ERR_PTR(-ENOMEM);
+}