1 files changed, 158 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xe/xe_preempt_fence.c b/drivers/gpu/drm/xe/xe_preempt_fence.c
new file mode 100644
index 0000000000..7bce2a3326
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe_preempt_fence.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2022 Intel Corporation
+ */
+
+#include "xe_preempt_fence.h"
+
+#include <linux/slab.h>
+
+#include "xe_exec_queue.h"
+#include "xe_vm.h"
+
+static void preempt_fence_work_func(struct work_struct *w)
+{
+	bool cookie = dma_fence_begin_signalling();
+	struct xe_preempt_fence *pfence =
+		container_of(w, typeof(*pfence), preempt_work);
+	struct xe_exec_queue *q = pfence->q;
+
+	if (pfence->error)
+		dma_fence_set_error(&pfence->base, pfence->error);
+	else
+		q->ops->suspend_wait(q);
+
+	dma_fence_signal(&pfence->base);
+	dma_fence_end_signalling(cookie);
+
+	xe_vm_queue_rebind_worker(q->vm);
+
+	xe_exec_queue_put(q);
+}
+
+static const char *
+preempt_fence_get_driver_name(struct dma_fence *fence)
+{
+	return "xe";
+}
+
+static const char *
+preempt_fence_get_timeline_name(struct dma_fence *fence)
+{
+	return "preempt";
+}
+
+static bool preempt_fence_enable_signaling(struct dma_fence *fence)
+{
+	struct xe_preempt_fence *pfence =
+		container_of(fence, typeof(*pfence), base);
+	struct xe_exec_queue *q = pfence->q;
+
+	pfence->error = q->ops->suspend(q);
+	queue_work(system_unbound_wq, &pfence->preempt_work);
+	return true;
+}
+
+static const struct dma_fence_ops preempt_fence_ops = {
+	.get_driver_name = preempt_fence_get_driver_name,
+	.get_timeline_name = preempt_fence_get_timeline_name,
+	.enable_signaling = preempt_fence_enable_signaling,
+};
+
+/**
+ * xe_preempt_fence_alloc() - Allocate a preempt fence with minimal
+ * initialization
+ *
+ * Allocate a preempt fence, and initialize its list head.
+ * If the preempt_fence allocated has been armed with
+ * xe_preempt_fence_arm(), it must be freed using dma_fence_put(). If not,
+ * it must be freed using xe_preempt_fence_free().
+ *
+ * Return: A struct xe_preempt_fence pointer used for calling into
+ * xe_preempt_fence_arm() or xe_preempt_fence_free().
+ * An error pointer on error.
+ */
+struct xe_preempt_fence *xe_preempt_fence_alloc(void)
+{
+	struct xe_preempt_fence *pfence;
+
+	pfence = kmalloc(sizeof(*pfence), GFP_KERNEL);
+	if (!pfence)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&pfence->link);
+	INIT_WORK(&pfence->preempt_work, preempt_fence_work_func);
+
+	return pfence;
+}
+
+/**
+ * xe_preempt_fence_free() - Free a preempt fence allocated using
+ * xe_preempt_fence_alloc().
+ * @pfence: pointer obtained from xe_preempt_fence_alloc();
+ *
+ * Free a preempt fence that has not yet been armed.
+ */
+void xe_preempt_fence_free(struct xe_preempt_fence *pfence)
+{
+	list_del(&pfence->link);
+	kfree(pfence);
+}
+
+/**
+ * xe_preempt_fence_arm() - Arm a preempt fence allocated using
+ * xe_preempt_fence_alloc().
+ * @pfence: The struct xe_preempt_fence pointer returned from
+ *          xe_preempt_fence_alloc().
+ * @q: The struct xe_exec_queue used for arming.
+ * @context: The dma-fence context used for arming.
+ * @seqno: The dma-fence seqno used for arming.
+ *
+ * Inserts the preempt fence into @context's timeline, takes @link off any
+ * list, and registers the struct xe_exec_queue as the xe_engine to be preempted.
+ *
+ * Return: A pointer to a struct dma_fence embedded into the preempt fence.
+ * This function doesn't error.
+ */
+struct dma_fence *
+xe_preempt_fence_arm(struct xe_preempt_fence *pfence, struct xe_exec_queue *q,
+		     u64 context, u32 seqno)
+{
+	list_del_init(&pfence->link);
+	pfence->q = xe_exec_queue_get(q);
+	dma_fence_init(&pfence->base, &preempt_fence_ops,
+		      &q->compute.lock, context, seqno);
+
+	return &pfence->base;
+}
+
+/**
+ * xe_preempt_fence_create() - Helper to create and arm a preempt fence.
+ * @q: The struct xe_exec_queue used for arming.
+ * @context: The dma-fence context used for arming.
+ * @seqno: The dma-fence seqno used for arming.
+ *
+ * Allocates and inserts the preempt fence into @context's timeline,
+ * and registers @e as the struct xe_exec_queue to be preempted.
+ *
+ * Return: A pointer to the resulting struct dma_fence on success. An error
+ * pointer on error. In particular if allocation fails it returns
+ * ERR_PTR(-ENOMEM);
+ */
+struct dma_fence *
+xe_preempt_fence_create(struct xe_exec_queue *q,
+			u64 context, u32 seqno)
+{
+	struct xe_preempt_fence *pfence;
+
+	pfence = xe_preempt_fence_alloc();
+	if (IS_ERR(pfence))
+		return ERR_CAST(pfence);
+
+	return xe_preempt_fence_arm(pfence, q, context, seqno);
+}
+
+bool xe_fence_is_xe_preempt(const struct dma_fence *fence)
+{
+	return fence->ops == &preempt_fence_ops;
+}