1 files changed, 134 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/i915_vma_snapshot.c b/drivers/gpu/drm/i915/i915_vma_snapshot.c
new file mode 100644
index 000000000000..2949ceea9884
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_vma_snapshot.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include "i915_vma_snapshot.h"
+#include "i915_vma_types.h"
+#include "i915_vma.h"
+
+/**
+ * i915_vma_snapshot_init - Initialize a struct i915_vma_snapshot from
+ * a struct i915_vma.
+ * @vsnap: The i915_vma_snapshot to init.
+ * @vma: A struct i915_vma used to initialize @vsnap.
+ * @name: Name associated with the snapshot. The character pointer needs to
+ * stay alive over the lifitime of the shapsot
+ */
+void i915_vma_snapshot_init(struct i915_vma_snapshot *vsnap,
+			    struct i915_vma *vma,
+			    const char *name)
+{
+	if (!i915_vma_is_pinned(vma))
+		assert_object_held(vma->obj);
+
+	vsnap->name = name;
+	vsnap->size = vma->size;
+	vsnap->obj_size = vma->obj->base.size;
+	vsnap->gtt_offset = vma->node.start;
+	vsnap->gtt_size = vma->node.size;
+	vsnap->page_sizes = vma->page_sizes.gtt;
+	vsnap->pages = vma->pages;
+	vsnap->pages_rsgt = NULL;
+	vsnap->mr = NULL;
+	if (vma->obj->mm.rsgt)
+		vsnap->pages_rsgt = i915_refct_sgt_get(vma->obj->mm.rsgt);
+	vsnap->mr = vma->obj->mm.region;
+	kref_init(&vsnap->kref);
+	vsnap->vma_resource = &vma->active;
+	vsnap->onstack = false;
+	vsnap->present = true;
+}
+
+/**
+ * i915_vma_snapshot_init_onstack - Initialize a struct i915_vma_snapshot from
+ * a struct i915_vma, but avoid kfreeing it on last put.
+ * @vsnap: The i915_vma_snapshot to init.
+ * @vma: A struct i915_vma used to initialize @vsnap.
+ * @name: Name associated with the snapshot. The character pointer needs to
+ * stay alive over the lifitime of the shapsot
+ */
+void i915_vma_snapshot_init_onstack(struct i915_vma_snapshot *vsnap,
+				    struct i915_vma *vma,
+				    const char *name)
+{
+	i915_vma_snapshot_init(vsnap, vma, name);
+	vsnap->onstack = true;
+}
+
+static void vma_snapshot_release(struct kref *ref)
+{
+	struct i915_vma_snapshot *vsnap =
+		container_of(ref, typeof(*vsnap), kref);
+
+	vsnap->present = false;
+	if (vsnap->pages_rsgt)
+		i915_refct_sgt_put(vsnap->pages_rsgt);
+	if (!vsnap->onstack)
+		kfree(vsnap);
+}
+
+/**
+ * i915_vma_snapshot_put - Put an i915_vma_snapshot pointer reference
+ * @vsnap: The pointer reference
+ */
+void i915_vma_snapshot_put(struct i915_vma_snapshot *vsnap)
+{
+	kref_put(&vsnap->kref, vma_snapshot_release);
+}
+
+/**
+ * i915_vma_snapshot_put_onstack - Put an onstcak i915_vma_snapshot pointer
+ * reference and varify that the structure is released
+ * @vsnap: The pointer reference
+ *
+ * This function is intended to be paired with a i915_vma_init_onstack()
+ * and should be called before exiting the scope that declared or
+ * freeing the structure that embedded @vsnap to verify that all references
+ * have been released.
+ */
+void i915_vma_snapshot_put_onstack(struct i915_vma_snapshot *vsnap)
+{
+	if (!kref_put(&vsnap->kref, vma_snapshot_release))
+		GEM_BUG_ON(1);
+}
+
+/**
+ * i915_vma_snapshot_resource_pin - Temporarily block the memory the
+ * vma snapshot is pointing to from being released.
+ * @vsnap: The vma snapshot.
+ * @lockdep_cookie: Pointer to bool needed for lockdep support. This needs
+ * to be passed to the paired i915_vma_snapshot_resource_unpin.
+ *
+ * This function will temporarily try to hold up a fence or similar structure
+ * and will therefore enter a fence signaling critical section.
+ *
+ * Return: true if we succeeded in blocking the memory from being released,
+ * false otherwise.
+ */
+bool i915_vma_snapshot_resource_pin(struct i915_vma_snapshot *vsnap,
+				    bool *lockdep_cookie)
+{
+	bool pinned = i915_active_acquire_if_busy(vsnap->vma_resource);
+
+	if (pinned)
+		*lockdep_cookie = dma_fence_begin_signalling();
+
+	return pinned;
+}
+
+/**
+ * i915_vma_snapshot_resource_unpin - Unblock vma snapshot memory from
+ * being released.
+ * @vsnap: The vma snapshot.
+ * @lockdep_cookie: Cookie returned from matching i915_vma_resource_pin().
+ *
+ * Might leave a fence signalling critical section and signal a fence.
+ */
+void i915_vma_snapshot_resource_unpin(struct i915_vma_snapshot *vsnap,
+				      bool lockdep_cookie)
+{
+	dma_fence_end_signalling(lockdep_cookie);
+
+	return i915_active_release(vsnap->vma_resource);
+}