[PATCH 5.15 002/120] drm/i915: Create a dummy object for gen6 ppgtt

Greg Kroah-Hartman
2022-12-05T19:36:49Z

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

[ Upstream commit b0b0f2d225da6fe58417fae37e3f797e2db27b62 ]

We currently have to special case vma->obj being NULL because
of gen6 ppgtt and mock_engine. Fix gen6 ppgtt, so we may soon
be able to remove a few checks. As the object only exists as
a fake object pointing to ggtt, we have no backing storage,
so no real object is created. It just has to look real enough.

Also kill pin_mutex, it's not compatible with ww locking,
and we can use the vm lock instead.

v2:
- Drop IS_SHRINKABLE and shorten overly long line
v3:
- Checkpatch fix for alignment

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211117142024.1043017-2-matthew.auld@intel.com
Stable-dep-of: 20e377e7b2e7 ("drm/i915/gt: Use i915_vm_put on ppgtt_create error paths")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/i915/gem/i915_gem_internal.c | 44 ++++---
drivers/gpu/drm/i915/gt/gen6_ppgtt.c | 123 +++++++++++--------
drivers/gpu/drm/i915/gt/gen6_ppgtt.h | 1 -
drivers/gpu/drm/i915/i915_drv.h | 4 +
4 files changed, 100 insertions(+), 72 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
index e5ae9c06510c..3c8de65bfb39 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
@@ -143,24 +143,10 @@ static const struct drm_i915_gem_object_ops i915_gem_object_internal_ops = {
.put_pages = i915_gem_object_put_pages_internal,
};

-/**
- * i915_gem_object_create_internal: create an object with volatile pages
- * @i915: the i915 device
- * @size: the size in bytes of backing storage to allocate for the object
- *
- * Creates a new object that wraps some internal memory for private use.
- * This object is not backed by swappable storage, and as such its contents
- * are volatile and only valid whilst pinned. If the object is reaped by the
- * shrinker, its pages and data will be discarded. Equally, it is not a full
- * GEM object and so not valid for access from userspace. This makes it useful
- * for hardware interfaces like ringbuffers (which are pinned from the time
- * the request is written to the time the hardware stops accessing it), but
- * not for contexts (which need to be preserved when not active for later
- * reuse). Note that it is not cleared upon allocation.
- */
struct drm_i915_gem_object *
-i915_gem_object_create_internal(struct drm_i915_private *i915,
- phys_addr_t size)
+__i915_gem_object_create_internal(struct drm_i915_private *i915,
+ const struct drm_i915_gem_object_ops *ops,
+ phys_addr_t size)
{
static struct lock_class_key lock_class;
struct drm_i915_gem_object *obj;
@@ -177,7 +163,7 @@ i915_gem_object_create_internal(struct drm_i915_private *i915,
return ERR_PTR(-ENOMEM);

drm_gem_private_object_init(&i915->drm, &obj->base, size);
- i915_gem_object_init(obj, &i915_gem_object_internal_ops, &lock_class, 0);
+ i915_gem_object_init(obj, ops, &lock_class, 0);
obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;

/*
@@ -197,3 +183,25 @@ i915_gem_object_create_internal(struct drm_i915_private *i915,

return obj;
}
+
+/**
+ * i915_gem_object_create_internal: create an object with volatile pages
+ * @i915: the i915 device
+ * @size: the size in bytes of backing storage to allocate for the object
+ *
+ * Creates a new object that wraps some internal memory for private use.
+ * This object is not backed by swappable storage, and as such its contents
+ * are volatile and only valid whilst pinned. If the object is reaped by the
+ * shrinker, its pages and data will be discarded. Equally, it is not a full
+ * GEM object and so not valid for access from userspace. This makes it useful
+ * for hardware interfaces like ringbuffers (which are pinned from the time
+ * the request is written to the time the hardware stops accessing it), but
+ * not for contexts (which need to be preserved when not active for later
+ * reuse). Note that it is not cleared upon allocation.
+ */
+struct drm_i915_gem_object *
+i915_gem_object_create_internal(struct drm_i915_private *i915,
+ phys_addr_t size)
+{
+ return __i915_gem_object_create_internal(i915, &i915_gem_object_internal_ops, size);
+}
diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
index 1aee5e6b1b23..557ef25be057 100644
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.c
@@ -262,13 +262,10 @@ static void gen6_ppgtt_cleanup(struct i915_address_space *vm)
{
struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(i915_vm_to_ppgtt(vm));

- __i915_vma_put(ppgtt->vma);
-
gen6_ppgtt_free_pd(ppgtt);
free_scratch(vm);

mutex_destroy(&ppgtt->flush);
- mutex_destroy(&ppgtt->pin_mutex);

free_pd(&ppgtt->base.vm, ppgtt->base.pd);
}
@@ -331,37 +328,6 @@ static const struct i915_vma_ops pd_vma_ops = {
.unbind_vma = pd_vma_unbind,
};

-static struct i915_vma *pd_vma_create(struct gen6_ppgtt *ppgtt, int size)
-{
- struct i915_ggtt *ggtt = ppgtt->base.vm.gt->ggtt;
- struct i915_vma *vma;
-
- GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
- GEM_BUG_ON(size > ggtt->vm.total);
-
- vma = i915_vma_alloc();
- if (!vma)
- return ERR_PTR(-ENOMEM);
-
- i915_active_init(&vma->active, NULL, NULL, 0);
-
- kref_init(&vma->ref);
- mutex_init(&vma->pages_mutex);
- vma->vm = i915_vm_get(&ggtt->vm);
- vma->ops = &pd_vma_ops;
- vma->private = ppgtt;
-
- vma->size = size;
- vma->fence_size = size;
- atomic_set(&vma->flags, I915_VMA_GGTT);
- vma->ggtt_view.type = I915_GGTT_VIEW_ROTATED; /* prevent fencing */
-
- INIT_LIST_HEAD(&vma->obj_link);
- INIT_LIST_HEAD(&vma->closed_link);
-
- return vma;
-}
-
int gen6_ppgtt_pin(struct i915_ppgtt *base, struct i915_gem_ww_ctx *ww)
{
struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(base);
@@ -378,24 +344,85 @@ int gen6_ppgtt_pin(struct i915_ppgtt *base, struct i915_gem_ww_ctx *ww)
if (atomic_add_unless(&ppgtt->pin_count, 1, 0))
return 0;

- if (mutex_lock_interruptible(&ppgtt->pin_mutex))
- return -EINTR;
+ /* grab the ppgtt resv to pin the object */
+ err = i915_vm_lock_objects(&ppgtt->base.vm, ww);
+ if (err)
+ return err;

/*
* PPGTT PDEs reside in the GGTT and consists of 512 entries. The
* allocator works in address space sizes, so it's multiplied by page
* size. We allocate at the top of the GTT to avoid fragmentation.
*/
- err = 0;
- if (!atomic_read(&ppgtt->pin_count))
+ if (!atomic_read(&ppgtt->pin_count)) {
err = i915_ggtt_pin(ppgtt->vma, ww, GEN6_PD_ALIGN, PIN_HIGH);
+
+ GEM_BUG_ON(ppgtt->vma->fence);
+ clear_bit(I915_VMA_CAN_FENCE_BIT, __i915_vma_flags(ppgtt->vma));
+ }
if (!err)
atomic_inc(&ppgtt->pin_count);
- mutex_unlock(&ppgtt->pin_mutex);

return err;
}

+static int pd_dummy_obj_get_pages(struct drm_i915_gem_object *obj)
+{
+ obj->mm.pages = ZERO_SIZE_PTR;
+ return 0;
+}
+
+static void pd_dummy_obj_put_pages(struct drm_i915_gem_object *obj,
+ struct sg_table *pages)
+{
+}
+
+static const struct drm_i915_gem_object_ops pd_dummy_obj_ops = {
+ .name = "pd_dummy_obj",
+ .get_pages = pd_dummy_obj_get_pages,
+ .put_pages = pd_dummy_obj_put_pages,
+};
+
+static struct i915_page_directory *
+gen6_alloc_top_pd(struct gen6_ppgtt *ppgtt)
+{
+ struct i915_ggtt * const ggtt = ppgtt->base.vm.gt->ggtt;
+ struct i915_page_directory *pd;
+ int err;
+
+ pd = __alloc_pd(I915_PDES);
+ if (unlikely(!pd))
+ return ERR_PTR(-ENOMEM);
+
+ pd->pt.base = __i915_gem_object_create_internal(ppgtt->base.vm.gt->i915,
+ &pd_dummy_obj_ops,
+ I915_PDES * SZ_4K);
+ if (IS_ERR(pd->pt.base)) {
+ err = PTR_ERR(pd->pt.base);
+ pd->pt.base = NULL;
+ goto err_pd;
+ }
+
+ pd->pt.base->base.resv = i915_vm_resv_get(&ppgtt->base.vm);
+ pd->pt.base->shares_resv_from = &ppgtt->base.vm;
+
+ ppgtt->vma = i915_vma_instance(pd->pt.base, &ggtt->vm, NULL);
+ if (IS_ERR(ppgtt->vma)) {
+ err = PTR_ERR(ppgtt->vma);
+ ppgtt->vma = NULL;
+ goto err_pd;
+ }
+
+ /* The dummy object we create is special, override ops.. */
+ ppgtt->vma->ops = &pd_vma_ops;
+ ppgtt->vma->private = ppgtt;
+ return pd;
+
+err_pd:
+ free_pd(&ppgtt->base.vm, pd);
+ return ERR_PTR(err);
+}
+
void gen6_ppgtt_unpin(struct i915_ppgtt *base)
{
struct gen6_ppgtt *ppgtt = to_gen6_ppgtt(base);
@@ -427,7 +454,6 @@ struct i915_ppgtt *gen6_ppgtt_create(struct intel_gt *gt)
return ERR_PTR(-ENOMEM);

mutex_init(&ppgtt->flush);
- mutex_init(&ppgtt->pin_mutex);

ppgtt_init(&ppgtt->base, gt);
ppgtt->base.vm.pd_shift = ilog2(SZ_4K * SZ_4K / sizeof(gen6_pte_t));
@@ -442,19 +468,13 @@ struct i915_ppgtt *gen6_ppgtt_create(struct intel_gt *gt)
ppgtt->base.vm.alloc_pt_dma = alloc_pt_dma;
ppgtt->base.vm.pte_encode = ggtt->vm.pte_encode;

- ppgtt->base.pd = __alloc_pd(I915_PDES);
- if (!ppgtt->base.pd) {
- err = -ENOMEM;
- goto err_free;
- }
-
err = gen6_ppgtt_init_scratch(ppgtt);
if (err)
- goto err_pd;
+ goto err_free;

- ppgtt->vma = pd_vma_create(ppgtt, GEN6_PD_SIZE);
- if (IS_ERR(ppgtt->vma)) {
- err = PTR_ERR(ppgtt->vma);
+ ppgtt->base.pd = gen6_alloc_top_pd(ppgtt);
+ if (IS_ERR(ppgtt->base.pd)) {
+ err = PTR_ERR(ppgtt->base.pd);
goto err_scratch;
}

@@ -462,10 +482,7 @@ struct i915_ppgtt *gen6_ppgtt_create(struct intel_gt *gt)

err_scratch:
free_scratch(&ppgtt->base.vm);
-err_pd:
- free_pd(&ppgtt->base.vm, ppgtt->base.pd);
err_free:
- mutex_destroy(&ppgtt->pin_mutex);
kfree(ppgtt);
return ERR_PTR(err);
}
diff --git a/drivers/gpu/drm/i915/gt/gen6_ppgtt.h b/drivers/gpu/drm/i915/gt/gen6_ppgtt.h
index 6a61a5c3a85a..9b498ca76ac6 100644
--- a/drivers/gpu/drm/i915/gt/gen6_ppgtt.h
+++ b/drivers/gpu/drm/i915/gt/gen6_ppgtt.h
@@ -19,7 +19,6 @@ struct gen6_ppgtt {
u32 pp_dir;

atomic_t pin_count;
- struct mutex pin_mutex;

bool scan_for_unused_pt;
};
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 005b1cec7007..236cfee1cbf0 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1905,6 +1905,10 @@ int i915_gem_evict_vm(struct i915_address_space *vm);
struct drm_i915_gem_object *
i915_gem_object_create_internal(struct drm_i915_private *dev_priv,
phys_addr_t size);
+struct drm_i915_gem_object *
+__i915_gem_object_create_internal(struct drm_i915_private *dev_priv,
+ const struct drm_i915_gem_object_ops *ops,
+ phys_addr_t size);

/* i915_gem_tiling.c */
static inline bool i915_gem_object_needs_bit17_swizzle(struct drm_i915_gem_object *obj)
--
2.35.1