Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
Documentation/gpu/drm-mm.rst | 12 ++
drivers/gpu/drm/Kconfig | 6 +
drivers/gpu/drm/Makefile | 2 +
drivers/gpu/drm/amd/amdgpu/Kconfig | 1 +
drivers/gpu/drm/drm_exec.c | 295 +++++++++++++++++++++++++++++
include/drm/drm_exec.h | 144 ++++++++++++++
6 files changed, 460 insertions(+)
create mode 100644 drivers/gpu/drm/drm_exec.c
create mode 100644 include/drm/drm_exec.h
diff --git a/Documentation/gpu/drm-mm.rst b/Documentation/gpu/drm-mm.rst
index a79fd3549ff8..a52e6f4117d6 100644
--- a/Documentation/gpu/drm-mm.rst
+++ b/Documentation/gpu/drm-mm.rst
@@ -493,6 +493,18 @@ DRM Sync Objects
.. kernel-doc:: drivers/gpu/drm/drm_syncobj.c
:export:
+DRM Execution context
+=====================
+
+.. kernel-doc:: drivers/gpu/drm/drm_exec.c
+ :doc: Overview
+
+.. kernel-doc:: include/drm/drm_exec.h
+ :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_exec.c
+ :export:
+
GPU Scheduler
=============
diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
index f42d4c6a19f2..1573d658fbb5 100644
--- a/drivers/gpu/drm/Kconfig
+++ b/drivers/gpu/drm/Kconfig
@@ -200,6 +200,12 @@ config DRM_TTM
GPU memory types. Will be enabled automatically if a device driver
uses it.
+config DRM_EXEC
+ tristate
+ depends on DRM
+ help
+ Execution context for command submissions
+
config DRM_BUDDY
tristate
depends on DRM
diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
index ab4460fcd63f..d40defbb0347 100644
--- a/drivers/gpu/drm/Makefile
+++ b/drivers/gpu/drm/Makefile
@@ -78,6 +78,8 @@ obj-$(CONFIG_DRM_PANEL_ORIENTATION_QUIRKS) += drm_panel_orientation_quirks.o
#
# Memory-management helpers
#
+#
+obj-$(CONFIG_DRM_EXEC) += drm_exec.o
obj-$(CONFIG_DRM_BUDDY) += drm_buddy.o
diff --git a/drivers/gpu/drm/amd/amdgpu/Kconfig b/drivers/gpu/drm/amd/amdgpu/Kconfig
index 5341b6b242c3..279fb3bba810 100644
--- a/drivers/gpu/drm/amd/amdgpu/Kconfig
+++ b/drivers/gpu/drm/amd/amdgpu/Kconfig
@@ -11,6 +11,7 @@ config DRM_AMDGPU
select DRM_SCHED
select DRM_TTM
select DRM_TTM_HELPER
+ select DRM_EXEC
select POWER_SUPPLY
select HWMON
select I2C
diff --git a/drivers/gpu/drm/drm_exec.c b/drivers/gpu/drm/drm_exec.c
new file mode 100644
index 000000000000..ed2106c22786
--- /dev/null
+++ b/drivers/gpu/drm/drm_exec.c
@@ -0,0 +1,295 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+#include <drm/drm_exec.h>
+#include <drm/drm_gem.h>
+#include <linux/dma-resv.h>
+
+/**
+ * DOC: Overview
+ *
+ * This component mainly abstracts the retry loop necessary for locking
+ * multiple GEM objects while preparing hardware operations (e.g. command
+ * submissions, page table updates etc..).
+ *
+ * If a contention is detected while locking a GEM object the cleanup procedure
+ * unlocks all previously locked GEM objects and locks the contended one first
+ * before locking any further objects.
+ *
+ * After an object is locked fences slots can optionally be reserved on the
+ * dma_resv object inside the GEM object.
+ *
+ * A typical usage pattern should look like this::
+ *
+ * struct drm_gem_object *obj;
+ * struct drm_exec exec;
+ * unsigned long index;
+ * int ret;
+ *
+ * drm_exec_init(&exec, true);
+ * drm_exec_while_not_all_locked(&exec) {
+ * ret = drm_exec_prepare_obj(&exec, boA, 1);
+ * drm_exec_continue_on_contention(&exec);
+ * if (ret)
+ * goto error;
+ *
+ * ret = drm_exec_lock(&exec, boB, 1);
+ * drm_exec_continue_on_contention(&exec);
+ * if (ret)
+ * goto error;
+ * }
+ *
+ * drm_exec_for_each_locked_object(&exec, index, obj) {
+ * dma_resv_add_fence(obj->resv, fence, DMA_RESV_USAGE_READ);
+ * ...
+ * }
+ * drm_exec_fini(&exec);
+ *
+ * See struct dma_exec for more details.
+ */
+
+/* Dummy value used to initially enter the retry loop */
+#define DRM_EXEC_DUMMY (void*)~0
+
+/* Initialize the drm_exec_objects container */
+static void drm_exec_objects_init(struct drm_exec_objects *container)
+{
+ container->objects = kmalloc(PAGE_SIZE, GFP_KERNEL);
+
+ /* If allocation here fails, just delay that till the first use */
+ container->max_objects = container->objects ?
+ PAGE_SIZE / sizeof(void *) : 0;
+ container->num_objects = 0;
+}
+
+/* Cleanup the drm_exec_objects container */
+static void drm_exec_objects_fini(struct drm_exec_objects *container)
+{
+ kvfree(container->objects);
+}
+
+/* Make sure we have enough room and add an object the container */
+static int drm_exec_objects_add(struct drm_exec_objects *container,
+ struct drm_gem_object *obj)
+{
+ if (unlikely(container->num_objects == container->max_objects)) {
+ size_t size = container->max_objects * sizeof(void *);
+ void *tmp;
+
+ tmp = kvrealloc(container->objects, size, size + PAGE_SIZE,
+ GFP_KERNEL);
+ if (!tmp)
+ return -ENOMEM;
+
+ container->objects = tmp;
+ container->max_objects += PAGE_SIZE / sizeof(void *);
+ }
+ drm_gem_object_get(obj);
+ container->objects[container->num_objects++] = obj;
+ return 0;
+}
+
+/* Unlock all objects and drop references */
+static void drm_exec_unlock_all(struct drm_exec *exec)
+{
+ struct drm_gem_object *obj;
+ unsigned long index;
+
+ drm_exec_for_each_duplicate_object(exec, index, obj)
+ drm_gem_object_put(obj);
+
+ drm_exec_for_each_locked_object(exec, index, obj) {
+ dma_resv_unlock(obj->resv);
+ drm_gem_object_put(obj);
+ }
+}
+
+/**
+ * drm_exec_init - initialize a drm_exec object
+ * @exec: the drm_exec object to initialize
+ * @interruptible: if locks should be acquired interruptible
+ *
+ * Initialize the object and make sure that we can track locked and duplicate
+ * objects.
+ */
+void drm_exec_init(struct drm_exec *exec, bool interruptible)
+{
+ exec->interruptible = interruptible;
+ drm_exec_objects_init(&exec->locked);
+ drm_exec_objects_init(&exec->duplicates);
+ exec->contended = DRM_EXEC_DUMMY;
+}
+EXPORT_SYMBOL(drm_exec_init);
+
+/**
+ * drm_exec_fini - finalize a drm_exec object
+ * @exec: the drm_exec object to finilize
+ *
+ * Unlock all locked objects, drop the references to objects and free all memory
+ * used for tracking the state.
+ */
+void drm_exec_fini(struct drm_exec *exec)
+{
+ drm_exec_unlock_all(exec);
+ drm_exec_objects_fini(&exec->locked);
+ drm_exec_objects_fini(&exec->duplicates);
+ if (exec->contended != DRM_EXEC_DUMMY) {
+ drm_gem_object_put(exec->contended);
+ ww_acquire_fini(&exec->ticket);
+ }
+}
+EXPORT_SYMBOL(drm_exec_fini);
+
+/**
+ * drm_exec_cleanup - cleanup when contention is detected
+ * @exec: the drm_exec object to cleanup
+ *
+ * Cleanup the current state and return true if we should stay inside the retry
+ * loop, false if there wasn't any contention detected and we can keep the
+ * objects locked.
+ */
+bool drm_exec_cleanup(struct drm_exec *exec)
+{
+ if (likely(!exec->contended)) {
+ ww_acquire_done(&exec->ticket);
+ return false;
+ }
+
+ if (likely(exec->contended == DRM_EXEC_DUMMY)) {
+ exec->contended = NULL;
+ ww_acquire_init(&exec->ticket, &reservation_ww_class);
+ return true;
+ }
+
+ drm_exec_unlock_all(exec);
+ exec->locked.num_objects = 0;
+ exec->duplicates.num_objects = 0;
+ return true;
+}
+EXPORT_SYMBOL(drm_exec_cleanup);
+
+/* Track the locked object in the xa and reserve fences */
+static int drm_exec_obj_locked(struct drm_exec_objects *container,
+ struct drm_gem_object *obj,
+ unsigned int num_fences)
+{
+ int ret;
+
+ if (container) {
+ ret = drm_exec_objects_add(container, obj);
+ if (ret)
+ return ret;
+ }
+
+ if (num_fences) {
+ ret = dma_resv_reserve_fences(obj->resv, num_fences);
+ if (ret)
+ goto error_erase;
+ }
+
+ return 0;
+
+error_erase:
+ if (container) {
+ --container->num_objects;
+ drm_gem_object_put(obj);
+ }
+ return ret;
+}
+
+/* Make sure the contended object is locked first */
+static int drm_exec_lock_contended(struct drm_exec *exec)
+{
+ struct drm_gem_object *obj = exec->contended;
+ int ret;
+
+ if (likely(!obj))
+ return 0;
+
+ if (exec->interruptible) {
+ ret = dma_resv_lock_slow_interruptible(obj->resv,
+ &exec->ticket);
+ if (unlikely(ret))
+ goto error_dropref;
+ } else {
+ dma_resv_lock_slow(obj->resv, &exec->ticket);
+ }
+
+ ret = drm_exec_obj_locked(&exec->locked, obj, 0);
+ if (unlikely(ret))
+ dma_resv_unlock(obj->resv);
+
+error_dropref:
+ /* Always cleanup the contention so that error handling can kick in */
+ drm_gem_object_put(obj);
+ exec->contended = NULL;
+ return ret;
+}
+
+/**
+ * drm_exec_prepare_obj - prepare a GEM object for use
+ * @exec: the drm_exec object with the state
+ * @obj: the GEM object to prepare
+ * @num_fences: how many fences to reserve
+ *
+ * Prepare a GEM object for use by locking it and reserving fence slots. All
+ * succesfully locked objects are put into the locked container. Duplicates
+ * detected as well and automatically moved into the duplicates container.
+ *
+ * Returns: -EDEADLK if a contention is detected, -ENOMEM when memory
+ * allocation failed and zero for success.
+ */
+int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
+ unsigned int num_fences)
+{
+ int ret;
+
+ ret = drm_exec_lock_contended(exec);
+ if (unlikely(ret))
+ return ret;
+
+ if (exec->interruptible)
+ ret = dma_resv_lock_interruptible(obj->resv, &exec->ticket);
+ else
+ ret = dma_resv_lock(obj->resv, &exec->ticket);
+
+ if (unlikely(ret == -EDEADLK)) {
+ drm_gem_object_get(obj);
+ exec->contended = obj;
+ return -EDEADLK;
+ }
+
+ if (unlikely(ret == -EALREADY)) {
+ struct drm_exec_objects *container = &exec->duplicates;
+
+ /*
+ * If this is the first locked GEM object it was most likely
+ * just contended. So don't add it to the duplicates, just
+ * reserve the fence slots.
+ */
+ if (exec->locked.num_objects && exec->locked.objects[0] == obj)
+ container = NULL;
+
+ ret = drm_exec_obj_locked(container, obj, num_fences);
+ if (ret)
+ return ret;
+
+ } else if (unlikely(ret)) {
+ return ret;
+
+ } else {
+ ret = drm_exec_obj_locked(&exec->locked, obj, num_fences);
+ if (ret)
+ goto error_unlock;
+ }
+
+ drm_gem_object_get(obj);
+ return 0;
+
+error_unlock:
+ dma_resv_unlock(obj->resv);
+ return ret;
+}
+EXPORT_SYMBOL(drm_exec_prepare_obj);
+
+MODULE_DESCRIPTION("DRM execution context");
+MODULE_LICENSE("Dual MIT/GPL");
diff --git a/include/drm/drm_exec.h b/include/drm/drm_exec.h
new file mode 100644
index 000000000000..f73981c6292e
--- /dev/null
+++ b/include/drm/drm_exec.h
@@ -0,0 +1,144 @@
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+#ifndef __DRM_EXEC_H__
+#define __DRM_EXEC_H__
+
+#include <linux/ww_mutex.h>
+
+struct drm_gem_object;
+
+/**
+ * struct drm_exec_objects - Container for GEM objects in a drm_exec
+ */
+struct drm_exec_objects {
+ unsigned int num_objects;
+ unsigned int max_objects;
+ struct drm_gem_object **objects;
+};
+
+/**
+ * drm_exec_objects_for_each - iterate over all the objects inside the container
+ */
+#define drm_exec_objects_for_each(array, index, obj) \
+ for (index = 0, obj = (array)->objects[0]; \
+ index < (array)->num_objects; \
+ ++index, obj = (array)->objects[index])
+
+/**
+ * struct drm_exec - Execution context
+ */
+struct drm_exec {
+ /**
+ * @interruptible: If locks should be taken interruptible
+ */
+ bool interruptible;
+
+ /**
+ * @ticket: WW ticket used for acquiring locks
+ */
+ struct ww_acquire_ctx ticket;
+
+ /**
+ * @locked: container for the locked GEM objects
+ */
+ struct drm_exec_objects locked;
+
+ /**
+ * @duplicates: container for the duplicated GEM objects
+ */
+ struct drm_exec_objects duplicates;
+
+ /**
+ * @contended: contended GEM object we backet of for.
+ */
+ struct drm_gem_object *contended;
+};
+
+/**
+ * drm_exec_for_each_locked_object - iterate over all the locked objects
+ * @exec: drm_exec object
+ * @index: unsigned long index for the iteration
+ * @obj: the current GEM object
+ *
+ * Iterate over all the locked GEM objects inside the drm_exec object.
+ */
+#define drm_exec_for_each_locked_object(exec, index, obj) \
+ drm_exec_objects_for_each(&(exec)->locked, index, obj)
+
+/**
+ * drm_exec_for_each_duplicate_object - iterate over all the duplicate objects
+ * @exec: drm_exec object
+ * @index: unsigned long index for the iteration
+ * @obj: the current GEM object
+ *
+ * Iterate over all the duplicate GEM objects inside the drm_exec object.
+ */
+#define drm_exec_for_each_duplicate_object(exec, index, obj) \
+ drm_exec_objects_for_each(&(exec)->duplicates, index, obj)
+
+/**
+ * drm_exec_while_not_all_locked - loop until all GEM objects are prepared
+ * @exec: drm_exec object
+ *
+ * Core functionality of the drm_exec object. Loops until all GEM objects are
+ * prepared and no more contention exists.
+ *
+ * At the beginning of the loop it is guaranteed that no GEM object is locked.
+ */
+#define drm_exec_while_not_all_locked(exec) \
+ while (drm_exec_cleanup(exec))
+
+/**
+ * drm_exec_continue_on_contention - continue the loop when we need to cleanup
+ * @exec: drm_exec object
+ *
+ * Control flow helper to continue when a contention was detected and we need to
+ * clean up and re-start the loop to prepare all GEM objects.
+ */
+#define drm_exec_continue_on_contention(exec) \
+ if (unlikely(drm_exec_is_contended(exec))) \
+ continue
+
+/**
+ * drm_exec_break_on_contention - break a subordinal loop on contention
+ * @exec: drm_exec object
+ *
+ * Control flow helper to break a subordinal loop when a contention was detected
+ * and we need to clean up and re-start the loop to prepare all GEM objects.
+ */
+#define drm_exec_break_on_contention(exec) \
+ if (unlikely(drm_exec_is_contended(exec))) \
+ break
+
+/**
+ * drm_exec_is_contended - check for contention
+ * @exec: drm_exec object
+ *
+ * Returns true if the drm_exec object has run into some contention while
+ * locking a GEM object and needs to clean up.
+ */
+static inline bool drm_exec_is_contended(struct drm_exec *exec)
+{
+ return !!exec->contended;
+}
+
+/**
+ * drm_exec_has_duplicates - check for duplicated GEM object
+ * @exec: drm_exec object
+ *
+ * Return true if the drm_exec object has encountered some already locked GEM
+ * objects while trying to lock them. This can happen if multiple GEM objects
+ * share the same underlying resv object.
+ */
+static inline bool drm_exec_has_duplicates(struct drm_exec *exec)
+{
+ return exec->duplicates.num_objects > 0;
+}
+
+void drm_exec_init(struct drm_exec *exec, bool interruptible);
+void drm_exec_fini(struct drm_exec *exec);
+bool drm_exec_cleanup(struct drm_exec *exec);
+int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
+ unsigned int num_fences);
+
+#endif
