On 8/20/2021 15:44, Matthew Brost wrote:
Introduce context parent-child relationship. Once this relationship is
created all pinning / unpinning operations are directed to the parent
context. The parent context is responsible for pinning all of its'
children and itself.
This is a precursor to the full GuC multi-lrc implementation but aligns
to how GuC mutli-lrc interface is defined - a single H2G is used
register / deregister all of the contexts simultaneously.
Subsequent patches in the series will implement the pinning / unpinning
operations for parent / child contexts.
v2:
(Daniel Vetter)
- Add kernel doc, add wrapper to access parent to ensure safety
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
---
drivers/gpu/drm/i915/gt/intel_context.c | 29 ++++++++++++++
drivers/gpu/drm/i915/gt/intel_context.h | 39 +++++++++++++++++++
drivers/gpu/drm/i915/gt/intel_context_types.h | 23 +++++++++++
3 files changed, 91 insertions(+)
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 508cfe5770c0..00d1aee6d199 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -404,6 +404,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
INIT_LIST_HEAD(&ce->destroyed_link);
No need for this blank line?
+ INIT_LIST_HEAD(&ce->guc_child_list);
+
/*
* Initialize fence to be complete as this is expected to be complete
* unless there is a pending schedule disable outstanding.
@@ -418,10 +420,17 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
void intel_context_fini(struct intel_context *ce)
{
+ struct intel_context *child, *next;
+
if (ce->timeline)
intel_timeline_put(ce->timeline);
i915_vm_put(ce->vm);
+ /* Need to put the creation ref for the children */
+ if (intel_context_is_parent(ce))
+ for_each_child_safe(ce, child, next)
+ intel_context_put(child);
+
mutex_destroy(&ce->pin_mutex);
i915_active_fini(&ce->active);
}
@@ -537,6 +546,26 @@ struct i915_request *intel_context_find_active_request(struct intel_context *ce)
return active;
}
+void intel_context_bind_parent_child(struct intel_context *parent,
+ struct intel_context *child)
+{
+ /*
+ * Callers responsibility to validate that this function is used
+ * correctly but we use GEM_BUG_ON here ensure that they do.
+ */
+ GEM_BUG_ON(!intel_engine_uses_guc(parent->engine));
+ GEM_BUG_ON(intel_context_is_pinned(parent));
+ GEM_BUG_ON(intel_context_is_child(parent));
+ GEM_BUG_ON(intel_context_is_pinned(child));
+ GEM_BUG_ON(intel_context_is_child(child));
+ GEM_BUG_ON(intel_context_is_parent(child));
+
+ parent->guc_number_children++;
+ list_add_tail(&child->guc_child_link,
+ &parent->guc_child_list);
+ child->parent = parent;
+}
+
#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
#include "selftest_context.c"
#endif
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index c41098950746..c2985822ab74 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -44,6 +44,45 @@ void intel_context_free(struct intel_context *ce);
int intel_context_reconfigure_sseu(struct intel_context *ce,
const struct intel_sseu sseu);
+static inline bool intel_context_is_child(struct intel_context *ce)
+{
+ return !!ce->parent;
+}
+
+static inline bool intel_context_is_parent(struct intel_context *ce)
+{
+ return !!ce->guc_number_children;
+}
+
+static inline bool intel_context_is_pinned(struct intel_context *ce);
No point declaring 'static inline' if there is no function body?
+
+static inline struct intel_context *
+intel_context_to_parent(struct intel_context *ce)
+{
+ if (intel_context_is_child(ce)) {
+ /*
+ * The parent holds ref count to the child so it is always safe
+ * for the parent to access the child, but the child has pointer
has pointer -> has a pointer
+ * to the parent without a ref. To ensure this is safe the child
+ * should only access the parent pointer while the parent is
+ * pinned.
+ */
+ GEM_BUG_ON(!intel_context_is_pinned(ce->parent));
+
+ return ce->parent;
+ } else {
+ return ce;
+ }
+}
+
+void intel_context_bind_parent_child(struct intel_context *parent,
+ struct intel_context *child);
+
+#define for_each_child(parent, ce)\
+ list_for_each_entry(ce, &(parent)->guc_child_list, guc_child_link)
+#define for_each_child_safe(parent, ce, cn)\
+ list_for_each_entry_safe(ce, cn, &(parent)->guc_child_list, guc_child_link)
Do these macros not need some kind of intel_context prefix? Or at least
be 'for_each_guc_child' given the naming of the list/link fields? But
maybe not if the guc_ is dropped from the variable names - see below.
+
/**
* intel_context_lock_pinned - Stablises the 'pinned' status of the HW context
* @ce - the context
diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h
index fd338a30617e..0fafc178cf2c 100644
--- a/drivers/gpu/drm/i915/gt/intel_context_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_context_types.h
@@ -213,6 +213,29 @@ struct intel_context {
*/
struct list_head destroyed_link;
+ /** anonymous struct for parent / children only members */
+ struct {
+ union {
+ /**
+ * @guc_child_list: parent's list of of children
+ * contexts, no protection as immutable after context
+ * creation
+ */
+ struct list_head guc_child_list;
+ /**
+ * @guc_child_link: child's link into parent's list of
+ * children
+ */
+ struct list_head guc_child_link;
+ };
+
+ /** @parent: pointer to parent if child */
+ struct intel_context *parent;
+
+ /** @guc_number_children: number of children if parent */
+ u8 guc_number_children;
These are not really a GuC specific fields? The parent/child thing might
only be necessary for GuC submission (although can you say it won't be
required by any future backend, such as the DRM scheduler?) but it is a
context level concept. None of the files changed in this patch are GuC
specific. So no need for 'guc_' prefix? Alternatively, if it all really
is completely GuC specific then the 'parent' field should also have the
prefix? Or even just name the outer struct 'guc_family' or something and
drop the prefixes from all the inner members.
John.
+ };
+
#ifdef CONFIG_DRM_I915_SELFTEST
/**
* @drop_schedule_enable: Force drop of schedule enable G2H for selftest
