Re: [PATCH 4/4] drm/i915: internal buffers use ttm backend
From: Robert Beckett
Date: Mon May 23 2022 - 11:52:30 EST
On 11/05/2022 15:14, Thomas Hellström wrote:
On Tue, 2022-05-03 at 19:13 +0000, Robert Beckett wrote:
refactor internal buffer backend to allocate volatile pages via
ttm pool allocator
Signed-off-by: Robert Beckett <bob.beckett@xxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/gem/i915_gem_internal.c | 264 ++++++++---------
--
drivers/gpu/drm/i915/gem/i915_gem_internal.h | 5 -
drivers/gpu/drm/i915/gem/i915_gem_ttm.c | 12 +-
drivers/gpu/drm/i915/gem/i915_gem_ttm.h | 12 +-
4 files changed, 125 insertions(+), 168 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.c
b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
index c698f95af15f..815ec9466cc0 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_internal.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.c
@@ -4,156 +4,119 @@
* Copyright © 2014-2016 Intel Corporation
*/
-#include <linux/scatterlist.h>
-#include <linux/slab.h>
-#include <linux/swiotlb.h>
-
+#include <drm/ttm/ttm_bo_driver.h>
+#include <drm/ttm/ttm_placement.h>
+#include "drm/ttm/ttm_bo_api.h"
+#include "gem/i915_gem_internal.h"
+#include "gem/i915_gem_region.h"
+#include "gem/i915_gem_ttm.h"
#include "i915_drv.h"
-#include "i915_gem.h"
-#include "i915_gem_internal.h"
-#include "i915_gem_object.h"
-#include "i915_scatterlist.h"
-#include "i915_utils.h"
-
-#define QUIET (__GFP_NORETRY | __GFP_NOWARN)
-#define MAYFAIL (__GFP_RETRY_MAYFAIL | __GFP_NOWARN)
-
-static void internal_free_pages(struct sg_table *st)
-{
- struct scatterlist *sg;
-
- for (sg = st->sgl; sg; sg = __sg_next(sg)) {
- if (sg_page(sg))
- __free_pages(sg_page(sg), get_order(sg-
length));
- }
-
- sg_free_table(st);
- kfree(st);
-}
-static int i915_gem_object_get_pages_internal(struct
drm_i915_gem_object *obj)
+static int i915_internal_get_pages(struct drm_i915_gem_object *obj)
{
- struct drm_i915_private *i915 = to_i915(obj->base.dev);
- struct sg_table *st;
- struct scatterlist *sg;
- unsigned int sg_page_sizes;
- unsigned int npages;
- int max_order;
- gfp_t gfp;
-
- max_order = MAX_ORDER;
-#ifdef CONFIG_SWIOTLB
- if (is_swiotlb_active(obj->base.dev->dev)) {
- unsigned int max_segment;
-
- max_segment = swiotlb_max_segment();
- if (max_segment) {
- max_segment = max_t(unsigned int,
max_segment,
- PAGE_SIZE) >> PAGE_SHIFT;
- max_order = min(max_order,
ilog2(max_segment));
- }
+ struct ttm_buffer_object *bo = i915_gem_to_ttm(obj);
+ struct ttm_operation_ctx ctx = {
+ .interruptible = true,
+ .no_wait_gpu = false,
+ };
+ struct ttm_place place = {
+ .fpfn = 0,
+ .lpfn = 0,
+ .mem_type = I915_PL_SYSTEM,
+ .flags = 0,
+ };
+ struct ttm_placement placement = {
+ .num_placement = 1,
+ .placement = &place,
+ .num_busy_placement = 0,
+ .busy_placement = NULL,
+ };
+ int ret;
+
+ ret = ttm_bo_validate(bo, &placement, &ctx);
+ if (ret) {
+ ret = i915_ttm_err_to_gem(ret);
+ return ret;
}
-#endif
- gfp = GFP_KERNEL | __GFP_HIGHMEM | __GFP_RECLAIMABLE;
- if (IS_I965GM(i915) || IS_I965G(i915)) {
- /* 965gm cannot relocate objects above 4GiB. */
- gfp &= ~__GFP_HIGHMEM;
- gfp |= __GFP_DMA32;
It looks like we're losing this restriction?
There is a flag to ttm_device_init() to make TTM only do __GFP_DMA32
allocations.
agreed. will fix for v2
+ if (bo->ttm && !ttm_tt_is_populated(bo->ttm)) {
+ ret = ttm_tt_populate(bo->bdev, bo->ttm, &ctx);
+ if (ret)
+ return ret;
}
-create_st:
- st = kmalloc(sizeof(*st), GFP_KERNEL);
- if (!st)
- return -ENOMEM;
+ if (!i915_gem_object_has_pages(obj)) {
+ struct i915_refct_sgt *rsgt =
+ i915_ttm_resource_get_st(obj, bo->resource);
- npages = obj->base.size / PAGE_SIZE;
- if (sg_alloc_table(st, npages, GFP_KERNEL)) {
- kfree(st);
- return -ENOMEM;
- }
+ if (IS_ERR(rsgt))
+ return PTR_ERR(rsgt);
- sg = st->sgl;
- st->nents = 0;
- sg_page_sizes = 0;
-
- do {
- int order = min(fls(npages) - 1, max_order);
- struct page *page;
-
- do {
- page = alloc_pages(gfp | (order ? QUIET :
MAYFAIL),
- order);
- if (page)
- break;
- if (!order--)
- goto err;
-
- /* Limit subsequent allocations as well */
- max_order = order;
- } while (1);
-
- sg_set_page(sg, page, PAGE_SIZE << order, 0);
- sg_page_sizes |= PAGE_SIZE << order;
- st->nents++;
-
- npages -= 1 << order;
- if (!npages) {
- sg_mark_end(sg);
- break;
- }
-
- sg = __sg_next(sg);
- } while (1);
-
- if (i915_gem_gtt_prepare_pages(obj, st)) {
- /* Failed to dma-map try again with single page sg
segments */
- if (get_order(st->sgl->length)) {
- internal_free_pages(st);
- max_order = 0;
- goto create_st;
- }
- goto err;
+ GEM_BUG_ON(obj->mm.rsgt);
+ obj->mm.rsgt = rsgt;
+ __i915_gem_object_set_pages(obj, &rsgt->table,
+ i915_sg_dma_sizes(rsgt-
table.sgl));
}
- __i915_gem_object_set_pages(obj, st, sg_page_sizes);
+ GEM_BUG_ON(bo->ttm && ((obj->base.size >> PAGE_SHIFT) < bo-
ttm->num_pages));
+ i915_ttm_adjust_lru(obj);
return 0;
+}
-err:
- sg_set_page(sg, NULL, 0, 0);
- sg_mark_end(sg);
- internal_free_pages(st);
+static const struct drm_i915_gem_object_ops
i915_gem_object_internal_ops = {
+ .name = "i915_gem_object_ttm",
+ .flags = I915_GEM_OBJECT_IS_SHRINKABLE,
- return -ENOMEM;
-}
+ .get_pages = i915_internal_get_pages,
+ .put_pages = i915_ttm_put_pages,
+ .adjust_lru = i915_ttm_adjust_lru,
+ .delayed_free = i915_ttm_delayed_free,
+};
-static void i915_gem_object_put_pages_internal(struct
drm_i915_gem_object *obj,
- struct sg_table
*pages)
+void i915_ttm_internal_bo_destroy(struct ttm_buffer_object *bo)
{
- i915_gem_gtt_finish_pages(obj, pages);
- internal_free_pages(pages);
+ struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
- obj->mm.dirty = false;
+ mutex_destroy(&obj->ttm.get_io_page.lock);
- __start_cpu_write(obj);
-}
+ if (obj->ttm.created) {
+ /* This releases all gem object bindings to the
backend. */
+ __i915_gem_free_object(obj);
-static const struct drm_i915_gem_object_ops
i915_gem_object_internal_ops = {
- .name = "i915_gem_object_internal",
- .flags = I915_GEM_OBJECT_IS_SHRINKABLE,
- .get_pages = i915_gem_object_get_pages_internal,
- .put_pages = i915_gem_object_put_pages_internal,
-};
+ call_rcu(&obj->rcu, __i915_gem_free_object_rcu);
+ } else {
+ __i915_gem_object_fini(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,
- const struct
drm_i915_gem_object_ops *ops,
- phys_addr_t size)
+i915_gem_object_create_internal(struct drm_i915_private *i915,
+ phys_addr_t size)
{
static struct lock_class_key lock_class;
struct drm_i915_gem_object *obj;
unsigned int cache_level;
+ struct ttm_operation_ctx ctx = {
+ .interruptible = true,
+ .no_wait_gpu = false,
+ };
+ int ret;
GEM_BUG_ON(!size);
GEM_BUG_ON(!IS_ALIGNED(size, PAGE_SIZE));
@@ -166,45 +129,34 @@ __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, ops, &lock_class, 0);
- obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;
+ i915_gem_object_init(obj, &i915_gem_object_internal_ops,
&lock_class,
+ I915_BO_ALLOC_VOLATILE);
+
+ INIT_LIST_HEAD(&obj->mm.region_link);
+
+ INIT_RADIX_TREE(&obj->ttm.get_io_page.radix, GFP_KERNEL |
__GFP_NOWARN);
+ mutex_init(&obj->ttm.get_io_page.lock);
- /*
- * Mark the object as volatile, such that the pages are
marked as
- * dontneed whilst they are still pinned. As soon as they are
unpinned
- * they are allowed to be reaped by the shrinker, and the
caller is
- * expected to repopulate - the contents of this object are
only valid
- * whilst active and pinned.
- */
- i915_gem_object_set_volatile(obj);
+ obj->base.vma_node.driver_private = i915_gem_to_ttm(obj);
+ ret = ttm_bo_init_reserved(&i915->bdev, i915_gem_to_ttm(obj),
size,
+ ttm_bo_type_kernel,
i915_ttm_sys_placement(),
+ 0, &ctx, NULL, NULL,
i915_ttm_internal_bo_destroy);
+ if (ret) {
+ ret = i915_ttm_err_to_gem(ret);
+ i915_gem_object_free(obj);
+ return ERR_PTR(ret);
+ }
+
+ obj->ttm.created = true;
obj->read_domains = I915_GEM_DOMAIN_CPU;
obj->write_domain = I915_GEM_DOMAIN_CPU;
-
+ obj->mem_flags &= ~I915_BO_FLAG_IOMEM;
+ obj->mem_flags |= I915_BO_FLAG_STRUCT_PAGE;
cache_level = HAS_LLC(i915) ? I915_CACHE_LLC :
I915_CACHE_NONE;
i915_gem_object_set_cache_coherency(obj, cache_level);
+ i915_gem_object_unlock(obj);
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);
While we don't have a TTM shmem backend ready yet for internal,
Did you consider setting up just yet another region,
INTEL_REGION_INTERNAL,
.class = INTEL_MEMORY_SYSTEM and
.instance = 1,
And make it create a TTM system region on integrated, and use
same region as INTEL_REGION_SMEM on dgfx.
I think ttm should automatically map that to I915_PL_SYSTEM and the
backwards mapping in i915_ttm_region() should never get called since
the object is never moved.
Then I figure it should suffice to just call
__i915_gem_ttm_object_init() and we could drop a lot of code.
i briefly considered using a new fake region, but with current precedent
mapping memory regions to real segemented memory areas I considered it
an abuse of the semantics of memory regions.
If we are happy to have fake regions, I can revert it back to a previous
design of using system region for discreet and add a fake region setup
for integrated.
Would this be preferred over the current design?
/Thomas
-}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_internal.h
b/drivers/gpu/drm/i915/gem/i915_gem_internal.h
index 6664e06112fc..524e1042b20f 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_internal.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_internal.h
@@ -15,9 +15,4 @@ struct drm_i915_private;
struct drm_i915_gem_object *
i915_gem_object_create_internal(struct drm_i915_private *i915,
phys_addr_t size);
-struct drm_i915_gem_object *
-__i915_gem_object_create_internal(struct drm_i915_private *i915,
- const struct
drm_i915_gem_object_ops *ops,
- phys_addr_t size);
-
#endif /* __I915_GEM_INTERNAL_H__ */
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index fdb3a1c18cb6..92195ead8c11 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -83,7 +83,7 @@ struct ttm_placement *i915_ttm_sys_placement(void)
return &i915_sys_placement;
}
-static int i915_ttm_err_to_gem(int err)
+int i915_ttm_err_to_gem(int err)
{
/* Fastpath */
if (likely(!err))
@@ -745,8 +745,8 @@ 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,
- struct ttm_placement *placement)
+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 = {
@@ -871,8 +871,8 @@ static int i915_ttm_migrate(struct
drm_i915_gem_object *obj,
return __i915_ttm_migrate(obj, mr, obj->flags);
}
-static void i915_ttm_put_pages(struct drm_i915_gem_object *obj,
- struct sg_table *st)
+void i915_ttm_put_pages(struct drm_i915_gem_object *obj,
+ struct sg_table *st)
{
/*
* We're currently not called from a shrinker, so put_pages()
@@ -995,7 +995,7 @@ void i915_ttm_adjust_lru(struct
drm_i915_gem_object *obj)
* it's not idle, and using the TTM destroyed list handling could
help us
* benefit from that.
*/
-static void i915_ttm_delayed_free(struct drm_i915_gem_object *obj)
+void i915_ttm_delayed_free(struct drm_i915_gem_object *obj)
{
GEM_BUG_ON(!obj->ttm.created);
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.h
b/drivers/gpu/drm/i915/gem/i915_gem_ttm.h
index 73e371aa3850..06701c46d8e2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.h
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.h
@@ -26,6 +26,7 @@ i915_gem_to_ttm(struct drm_i915_gem_object *obj)
* i915 ttm gem object destructor. Internal use only.
*/
void i915_ttm_bo_destroy(struct ttm_buffer_object *bo);
+void i915_ttm_internal_bo_destroy(struct ttm_buffer_object *bo);
/**
* i915_ttm_to_gem - Convert a struct ttm_buffer_object to an
embedding
@@ -37,8 +38,10 @@ void i915_ttm_bo_destroy(struct ttm_buffer_object
*bo);
static inline struct drm_i915_gem_object *
i915_ttm_to_gem(struct ttm_buffer_object *bo)
{
- if (bo->destroy != i915_ttm_bo_destroy)
+ if (bo->destroy != i915_ttm_bo_destroy &&
+ bo->destroy != i915_ttm_internal_bo_destroy) {
return NULL;
+ }
return container_of(bo, struct drm_i915_gem_object,
__do_not_access);
}
@@ -66,6 +69,7 @@ i915_ttm_resource_get_st(struct drm_i915_gem_object
*obj,
struct ttm_resource *res);
void i915_ttm_adjust_lru(struct drm_i915_gem_object *obj);
+void i915_ttm_delayed_free(struct drm_i915_gem_object *obj);
int i915_ttm_purge(struct drm_i915_gem_object *obj);
@@ -92,4 +96,10 @@ static inline bool i915_ttm_cpu_maps_iomem(struct
ttm_resource *mem)
/* Once / if we support GGTT, this is also false for cached
ttm_tts */
return mem->mem_type != I915_PL_SYSTEM;
}
+
+int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
+ struct ttm_placement *placement);
+void i915_ttm_put_pages(struct drm_i915_gem_object *obj, struct
sg_table *st);
+int i915_ttm_err_to_gem(int err);
+
#endif