[Intel-gfx] [PATCH v4 1/3] drm/i915/gem: Implement object migration
Thomas Hellström
thomas.hellstrom at linux.intel.com
Tue Jun 29 11:37:11 UTC 2021
Introduce an interface to migrate objects between regions.
This is primarily intended to migrate objects to LMEM for display and
to SYSTEM for dma-buf, but might be reused in one form or another for
performance-based migration.
v2:
- Verify that the memory region given as an id really exists.
(Reported by Matthew Auld)
- Call i915_gem_object_{init,release}_memory_region() when switching region
to handle also switching region lists. (Reported by Matthew Auld)
v3:
- Fix i915_gem_object_can_migrate() to return true if object is already in
the correct region, even if the object ops doesn't have a migrate()
callback.
- Update typo in commit message.
- Fix kerneldoc of i915_gem_object_wait_migration().
v4:
- Improve documentation (Suggested by Mattew Auld and Michael Ruhl)
- Always assume TTM migration hits a TTM move and unsets the pages through
move_notify. (Reported by Matthew Auld)
- Add a dma_fence_might_wait() annotation to
i915_gem_object_wait_migration() (Suggested by Daniel Vetter)
Reported-by: kernel test robot <lkp at intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
Reviewed-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
---
drivers/gpu/drm/i915/gem/i915_gem_object.c | 112 ++++++++++++++++++
drivers/gpu/drm/i915/gem/i915_gem_object.h | 12 ++
.../gpu/drm/i915/gem/i915_gem_object_types.h | 9 ++
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 77 ++++++++++--
drivers/gpu/drm/i915/gem/i915_gem_wait.c | 19 +++
5 files changed, 217 insertions(+), 12 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.c b/drivers/gpu/drm/i915/gem/i915_gem_object.c
index 07e8ff9a8aae..225b77fb4314 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.c
@@ -513,6 +513,118 @@ bool i915_gem_object_has_iomem(const struct drm_i915_gem_object *obj)
return obj->mem_flags & I915_BO_FLAG_IOMEM;
}
+/**
+ * i915_gem_object_can_migrate - Whether an object likely can be migrated
+ *
+ * @obj: The object to migrate
+ * @id: The region intended to migrate to
+ *
+ * Check whether the object backend supports migration to the
+ * given region. Note that pinning may affect the ability to migrate as
+ * returned by this function.
+ *
+ * This function is primarily intended as a helper for checking the
+ * possibility to migrate objects and might be slightly less permissive
+ * than i915_gem_object_migrate() when it comes to objects with the
+ * I915_BO_ALLOC_USER flag set.
+ *
+ * Return: true if migration is possible, false otherwise.
+ */
+bool i915_gem_object_can_migrate(struct drm_i915_gem_object *obj,
+ enum intel_region_id id)
+{
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
+ unsigned int num_allowed = obj->mm.n_placements;
+ struct intel_memory_region *mr;
+ unsigned int i;
+
+ GEM_BUG_ON(id >= INTEL_REGION_UNKNOWN);
+ GEM_BUG_ON(obj->mm.madv != I915_MADV_WILLNEED);
+
+ mr = i915->mm.regions[id];
+ if (!mr)
+ return false;
+
+ if (obj->mm.region == mr)
+ return true;
+
+ if (!i915_gem_object_evictable(obj))
+ return false;
+
+ if (!obj->ops->migrate)
+ return false;
+
+ if (!(obj->flags & I915_BO_ALLOC_USER))
+ return true;
+
+ if (num_allowed == 0)
+ return false;
+
+ for (i = 0; i < num_allowed; ++i) {
+ if (mr == obj->mm.placements[i])
+ return true;
+ }
+
+ return false;
+}
+
+/**
+ * i915_gem_object_migrate - Migrate an object to the desired region id
+ * @obj: The object to migrate.
+ * @ww: An optional struct i915_gem_ww_ctx. If NULL, the backend may
+ * not be successful in evicting other objects to make room for this object.
+ * @id: The region id to migrate to.
+ *
+ * Attempt to migrate the object to the desired memory region. The
+ * object backend must support migration and the object may not be
+ * pinned, (explicitly pinned pages or pinned vmas). The object must
+ * be locked.
+ * On successful completion, the object will have pages pointing to
+ * memory in the new region, but an async migration task may not have
+ * completed yet, and to accomplish that, i915_gem_object_wait_migration()
+ * must be called.
+ *
+ * This function is a bit more permissive than i915_gem_object_can_migrate()
+ * to allow for migrating objects where the caller knows exactly what is
+ * happening. For example within selftests. More specifically this
+ * function allows migrating I915_BO_ALLOC_USER objects to regions
+ * that are not in the list of allowable regions.
+ *
+ * Note: the @ww parameter is not used yet, but included to make sure
+ * callers put some effort into obtaining a valid ww ctx if one is
+ * available.
+ *
+ * Return: 0 on success. Negative error code on failure. In particular may
+ * return -ENXIO on lack of region space, -EDEADLK for deadlock avoidance
+ * if @ww is set, -EINTR or -ERESTARTSYS if signal pending, and
+ * -EBUSY if the object is pinned.
+ */
+int i915_gem_object_migrate(struct drm_i915_gem_object *obj,
+ struct i915_gem_ww_ctx *ww,
+ enum intel_region_id id)
+{
+ struct drm_i915_private *i915 = to_i915(obj->base.dev);
+ struct intel_memory_region *mr;
+
+ GEM_BUG_ON(id >= INTEL_REGION_UNKNOWN);
+ GEM_BUG_ON(obj->mm.madv != I915_MADV_WILLNEED);
+ assert_object_held(obj);
+
+ mr = i915->mm.regions[id];
+ GEM_BUG_ON(!mr);
+
+ if (obj->mm.region == mr)
+ return 0;
+
+ if (!i915_gem_object_evictable(obj))
+ return -EBUSY;
+
+ if (!obj->ops->migrate)
+ return -EOPNOTSUPP;
+
+ return obj->ops->migrate(obj, mr);
+}
+
void i915_gem_init__objects(struct drm_i915_private *i915)
{
INIT_WORK(&i915->mm.free_work, __i915_gem_free_work);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object.h b/drivers/gpu/drm/i915/gem/i915_gem_object.h
index ea3224a480c4..8cbd7a5334e2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object.h
@@ -17,6 +17,8 @@
#include "i915_gem_ww.h"
#include "i915_vma_types.h"
+enum intel_region_id;
+
/*
* XXX: There is a prevalence of the assumption that we fit the
* object's page count inside a 32bit _signed_ variable. Let's document
@@ -597,6 +599,16 @@ bool i915_gem_object_migratable(struct drm_i915_gem_object *obj);
bool i915_gem_object_validates_to_lmem(struct drm_i915_gem_object *obj);
+int i915_gem_object_migrate(struct drm_i915_gem_object *obj,
+ struct i915_gem_ww_ctx *ww,
+ enum intel_region_id id);
+
+bool i915_gem_object_can_migrate(struct drm_i915_gem_object *obj,
+ enum intel_region_id id);
+
+int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
+ unsigned int flags);
+
#ifdef CONFIG_MMU_NOTIFIER
static inline bool
i915_gem_object_is_userptr(struct drm_i915_gem_object *obj)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
index 441f913c87e6..ef3de2ae9723 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
@@ -18,6 +18,7 @@
struct drm_i915_gem_object;
struct intel_fronbuffer;
+struct intel_memory_region;
/*
* struct i915_lut_handle tracks the fast lookups from handle to vma used
@@ -77,6 +78,14 @@ struct drm_i915_gem_object_ops {
* delayed_free - Override the default delayed free implementation
*/
void (*delayed_free)(struct drm_i915_gem_object *obj);
+
+ /**
+ * migrate - Migrate object to a different region either for
+ * pinning or for as long as the object lock is held.
+ */
+ int (*migrate)(struct drm_i915_gem_object *obj,
+ struct intel_memory_region *mr);
+
void (*release)(struct drm_i915_gem_object *obj);
const struct vm_operations_struct *mmap_ops;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index c39d982c4fa6..521ab740001a 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -617,7 +617,8 @@ struct ttm_device_funcs *i915_ttm_driver(void)
return &i915_ttm_bo_driver;
}
-static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
+static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
+ struct ttm_placement *placement)
{
struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
struct ttm_operation_ctx ctx = {
@@ -625,19 +626,12 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
.no_wait_gpu = false,
};
struct sg_table *st;
- struct ttm_place requested, busy[I915_TTM_MAX_PLACEMENTS];
- struct ttm_placement placement;
int real_num_busy;
int ret;
- GEM_BUG_ON(obj->mm.n_placements > I915_TTM_MAX_PLACEMENTS);
-
- /* Move to the requested placement. */
- i915_ttm_placement_from_obj(obj, &requested, busy, &placement);
-
/* First try only the requested placement. No eviction. */
- real_num_busy = fetch_and_zero(&placement.num_busy_placement);
- ret = ttm_bo_validate(bo, &placement, &ctx);
+ real_num_busy = fetch_and_zero(&placement->num_busy_placement);
+ ret = ttm_bo_validate(bo, placement, &ctx);
if (ret) {
ret = i915_ttm_err_to_gem(ret);
/*
@@ -652,8 +646,8 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
* If the initial attempt fails, allow all accepted placements,
* evicting if necessary.
*/
- placement.num_busy_placement = real_num_busy;
- ret = ttm_bo_validate(bo, &placement, &ctx);
+ placement->num_busy_placement = real_num_busy;
+ ret = ttm_bo_validate(bo, placement, &ctx);
if (ret)
return i915_ttm_err_to_gem(ret);
}
@@ -668,6 +662,7 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
i915_ttm_adjust_gem_after_move(obj);
}
+ GEM_WARN_ON(obj->mm.pages);
/* Object either has a page vector or is an iomem object */
st = bo->ttm ? i915_ttm_tt_get_st(bo->ttm) : obj->ttm.cached_io_st;
if (IS_ERR(st))
@@ -678,6 +673,63 @@ static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
return ret;
}
+static int i915_ttm_get_pages(struct drm_i915_gem_object *obj)
+{
+ struct ttm_place requested, busy[I915_TTM_MAX_PLACEMENTS];
+ struct ttm_placement placement;
+
+ GEM_BUG_ON(obj->mm.n_placements > I915_TTM_MAX_PLACEMENTS);
+
+ /* Move to the requested placement. */
+ i915_ttm_placement_from_obj(obj, &requested, busy, &placement);
+
+ return __i915_ttm_get_pages(obj, &placement);
+}
+
+/**
+ * DOC: Migration vs eviction
+ *
+ * GEM migration may not be the same as TTM migration / eviction. If
+ * the TTM core decides to evict an object it may be evicted to a
+ * TTM memory type that is not in the object's allowable GEM regions, or
+ * in fact theoretically to a TTM memory type that doesn't correspond to
+ * a GEM memory region. In that case the object's GEM region is not
+ * updated, and the data is migrated back to the GEM region at
+ * get_pages time. TTM may however set up CPU ptes to the object even
+ * when it is evicted.
+ * Gem forced migration using the i915_ttm_migrate() op, is allowed even
+ * to regions that are not in the object's list of allowable placements.
+ */
+static int i915_ttm_migrate(struct drm_i915_gem_object *obj,
+ struct intel_memory_region *mr)
+{
+ struct ttm_place requested;
+ struct ttm_placement placement;
+ int ret;
+
+ i915_ttm_place_from_region(mr, &requested, obj->flags);
+ placement.num_placement = 1;
+ placement.num_busy_placement = 1;
+ placement.placement = &requested;
+ placement.busy_placement = &requested;
+
+ ret = __i915_ttm_get_pages(obj, &placement);
+ if (ret)
+ return ret;
+
+ /*
+ * Reinitialize the region bindings. This is primarily
+ * required for objects where the new region is not in
+ * its allowable placements.
+ */
+ if (obj->mm.region != mr) {
+ i915_gem_object_release_memory_region(obj);
+ i915_gem_object_init_memory_region(obj, mr);
+ }
+
+ return 0;
+}
+
static void i915_ttm_put_pages(struct drm_i915_gem_object *obj,
struct sg_table *st)
{
@@ -814,6 +866,7 @@ static const struct drm_i915_gem_object_ops i915_gem_ttm_obj_ops = {
.truncate = i915_ttm_purge,
.adjust_lru = i915_ttm_adjust_lru,
.delayed_free = i915_ttm_delayed_free,
+ .migrate = i915_ttm_migrate,
.mmap_offset = i915_ttm_mmap_offset,
.mmap_ops = &vm_ops_ttm,
};
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_wait.c b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
index 1070d3afdce7..190e221eaf81 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_wait.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_wait.c
@@ -290,3 +290,22 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
i915_gem_object_put(obj);
return ret;
}
+
+/**
+ * i915_gem_object_wait_migration - Sync an accelerated migration operation
+ * @obj: The migrating object.
+ * @flags: waiting flags. Currently supports only I915_WAIT_INTERRUPTIBLE.
+ *
+ * Wait for any pending async migration operation on the object,
+ * whether it's explicitly (i915_gem_object_migrate()) or implicitly
+ * (swapin, initial clearing) initiated.
+ *
+ * Return: 0 if successful, -ERESTARTSYS if a signal was hit during waiting.
+ */
+int i915_gem_object_wait_migration(struct drm_i915_gem_object *obj,
+ unsigned int flags)
+{
+ dma_fence_might_wait();
+ /* NOP for now. */
+ return 0;
+}
--
2.31.1
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