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Code Issues Releases Wiki Activity

drm/i915: Avoid using the i915_fence_array when collecting dependencies

Browse source 
Since the gt migration code was using only a single fence for
dependencies, these were collected in a dma_fence_array. However, it
turns out that it's illegal to use some dma_fences in a dma_fence_array,
in particular other dma_fence_arrays and dma_fence_chains, and this
causes trouble for us moving forward.

Have the gt migration code instead take a const struct i915_deps for
dependencies. This means we can skip the dma_fence_array creation
and instead pass the struct i915_deps instead to circumvent the
problem.

v2:
- Make the prev_deps() function static. (kernel test robot <lkp@intel.com>)
- Update the struct i915_deps kerneldoc.
v4:
- Rebase.

Fixes: 5652df829b ("drm/i915/ttm: Update i915_gem_obj_copy_ttm() to be asynchronous")
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211221200050.436316-2-thomas.hellstrom@linux.intel.com
This commit is contained in:
Thomas Hellström 2021-12-21 21:00:47 +01:00
parent 1c40d40f68
commit 1193081710
6 changed files with 91 additions and 112 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

129
drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
View file

@ -3,8 +3,6 @@
* Copyright © 2021 Intel Corporation
*/
#include <linux/dma-fence-array.h>
#include <drm/ttm/ttm_bo_driver.h>
#include "i915_drv.h"
@ -44,17 +42,12 @@ void i915_ttm_migrate_set_failure_modes(bool gpu_migration,
#endif
/**
* DOC: Set of utilities to dynamically collect dependencies and
* eventually coalesce them into a single fence which is fed into
* the GT migration code, since it only accepts a single dependency
* fence.
* The single fence returned from these utilities, in the case of
* dependencies from multiple fence contexts, a struct dma_fence_array,
* since the i915 request code can break that up and await the individual
* fences.
* DOC: Set of utilities to dynamically collect dependencies into a
* structure which is fed into the GT migration code.
*
* Once we can do async unbinding, this is also needed to coalesce
* the migration fence with the unbind fences.
* the migration fence with the unbind fences if these are coalesced
* post-migration.
*
* While collecting the individual dependencies, we store the refcounted
* struct dma_fence pointers in a realloc-managed pointer array, since
@ -65,32 +58,13 @@ void i915_ttm_migrate_set_failure_modes(bool gpu_migration,
* A struct i915_deps need to be initialized using i915_deps_init().
* If i915_deps_add_dependency() or i915_deps_add_resv() return an
* error code they will internally call i915_deps_fini(), which frees
* all internal references and allocations. After a call to
* i915_deps_to_fence(), or i915_deps_sync(), the struct should similarly
* be viewed as uninitialized.
* all internal references and allocations.
*
* We might want to break this out into a separate file as a utility.
*/
#define I915_DEPS_MIN_ALLOC_CHUNK 8U
/**
* struct i915_deps - Collect dependencies into a single dma-fence
* @single: Storage for pointer if the collection is a single fence.
* @fence: Allocated array of fence pointers if more than a single fence;
* otherwise points to the address of @single.
* @num_deps: Current number of dependency fences.
* @fences_size: Size of the @fences array in number of pointers.
* @gfp: Allocation mode.
*/
struct i915_deps {
struct dma_fence *single;
struct dma_fence **fences;
unsigned int num_deps;
unsigned int fences_size;
gfp_t gfp;
};
static void i915_deps_reset_fences(struct i915_deps *deps)
{
if (deps->fences != &deps->single)
@ -163,7 +137,7 @@ static int i915_deps_grow(struct i915_deps *deps, struct dma_fence *fence,
return ret;
}
static int i915_deps_sync(struct i915_deps *deps,
static int i915_deps_sync(const struct i915_deps *deps,
const struct ttm_operation_ctx *ctx)
{
struct dma_fence **fences = deps->fences;
@ -183,7 +157,6 @@ static int i915_deps_sync(struct i915_deps *deps,
break;
}
i915_deps_fini(deps);
return ret;
}
@ -221,34 +194,6 @@ static int i915_deps_add_dependency(struct i915_deps *deps,
return i915_deps_grow(deps, fence, ctx);
}
static struct dma_fence *i915_deps_to_fence(struct i915_deps *deps,
const struct ttm_operation_ctx *ctx)
{
struct dma_fence_array *array;
if (deps->num_deps == 0)
return NULL;
if (deps->num_deps == 1) {
deps->num_deps = 0;
return deps->fences[0];
}
/*
* TODO: Alter the allocation mode here to not try too hard to
* make things async.
*/
array = dma_fence_array_create(deps->num_deps, deps->fences, 0, 0,
false);
if (!array)
return ERR_PTR(i915_deps_sync(deps, ctx));
deps->fences = NULL;
i915_deps_reset_fences(deps);
return &array->base;
}
static int i915_deps_add_resv(struct i915_deps *deps, struct dma_resv *resv,
bool all, const bool no_excl,
const struct ttm_operation_ctx *ctx)
@ -387,7 +332,7 @@ static struct dma_fence *i915_ttm_accel_move(struct ttm_buffer_object *bo,
struct ttm_resource *dst_mem,
struct ttm_tt *dst_ttm,
struct sg_table *dst_st,
struct dma_fence *dep)
const struct i915_deps *deps)
{
struct drm_i915_private *i915 = container_of(bo->bdev, typeof(*i915),
bdev);
@ -411,7 +356,7 @@ static struct dma_fence *i915_ttm_accel_move(struct ttm_buffer_object *bo,
return ERR_PTR(-EINVAL);
intel_engine_pm_get(to_gt(i915)->migrate.context->engine);
ret = intel_context_migrate_clear(to_gt(i915)->migrate.context, dep,
ret = intel_context_migrate_clear(to_gt(i915)->migrate.context, deps,
dst_st->sgl, dst_level,
i915_ttm_gtt_binds_lmem(dst_mem),
0, &rq);
@ -425,7 +370,7 @@ static struct dma_fence *i915_ttm_accel_move(struct ttm_buffer_object *bo,
src_level = i915_ttm_cache_level(i915, bo->resource, src_ttm);
intel_engine_pm_get(to_gt(i915)->migrate.context->engine);
ret = intel_context_migrate_copy(to_gt(i915)->migrate.context,
dep, src_rsgt->table.sgl,
deps, src_rsgt->table.sgl,
src_level,
i915_ttm_gtt_binds_lmem(bo->resource),
dst_st->sgl, dst_level,
@ -610,10 +555,11 @@ i915_ttm_memcpy_work_arm(struct i915_ttm_memcpy_work *work,
}
static struct dma_fence *
__i915_ttm_move(struct ttm_buffer_object *bo, bool clear,
__i915_ttm_move(struct ttm_buffer_object *bo,
const struct ttm_operation_ctx *ctx, bool clear,
struct ttm_resource *dst_mem, struct ttm_tt *dst_ttm,
struct i915_refct_sgt *dst_rsgt, bool allow_accel,
struct dma_fence *move_dep)
const struct i915_deps *move_deps)
{
struct i915_ttm_memcpy_work *copy_work = NULL;
struct i915_ttm_memcpy_arg _arg, *arg = &_arg;
@ -621,7 +567,7 @@ __i915_ttm_move(struct ttm_buffer_object *bo, bool clear,
if (allow_accel) {
fence = i915_ttm_accel_move(bo, clear, dst_mem, dst_ttm,
&dst_rsgt->table, move_dep);
&dst_rsgt->table, move_deps);
/*
* We only need to intercept the error when moving to lmem.
@ -655,8 +601,8 @@ __i915_ttm_move(struct ttm_buffer_object *bo, bool clear,
if (!IS_ERR(fence))
goto out;
} else if (move_dep) {
int err = dma_fence_wait(move_dep, true);
} else if (move_deps) {
int err = i915_deps_sync(move_deps, ctx);
if (err)
return ERR_PTR(err);
@ -680,29 +626,21 @@ __i915_ttm_move(struct ttm_buffer_object *bo, bool clear,
return fence;
}
static struct dma_fence *prev_fence(struct ttm_buffer_object *bo,
struct ttm_operation_ctx *ctx)
static int
prev_deps(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,
struct i915_deps *deps)
{
struct i915_deps deps;
int ret;
/*
* Instead of trying hard with GFP_KERNEL to allocate memory,
* the dependency collection will just sync if it doesn't
* succeed.
*/
i915_deps_init(&deps, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
ret = i915_deps_add_dependency(&deps, bo->moving, ctx);
ret = i915_deps_add_dependency(deps, bo->moving, ctx);
if (!ret)
/*
* TODO: Only await excl fence here, and shared fences before
* signaling the migration fence.
*/
ret = i915_deps_add_resv(&deps, bo->base.resv, true, false, ctx);
if (ret)
return ERR_PTR(ret);
ret = i915_deps_add_resv(deps, bo->base.resv, true, false, ctx);
return i915_deps_to_fence(&deps, ctx);
return ret;
}
/**
@ -756,16 +694,18 @@ int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
clear = !i915_ttm_cpu_maps_iomem(bo->resource) && (!ttm || !ttm_tt_is_populated(ttm));
if (!(clear && ttm && !(ttm->page_flags & TTM_TT_FLAG_ZERO_ALLOC))) {
struct dma_fence *dep = prev_fence(bo, ctx);
struct i915_deps deps;
if (IS_ERR(dep)) {
i915_deps_init(&deps, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
ret = prev_deps(bo, ctx, &deps);
if (ret) {
i915_refct_sgt_put(dst_rsgt);
return PTR_ERR(dep);
return ret;
}
migration_fence = __i915_ttm_move(bo, clear, dst_mem, bo->ttm,
dst_rsgt, true, dep);
dma_fence_put(dep);
migration_fence = __i915_ttm_move(bo, ctx, clear, dst_mem, bo->ttm,
dst_rsgt, true, &deps);
i915_deps_fini(&deps);
}
/* We can possibly get an -ERESTARTSYS here */
@ -826,7 +766,7 @@ int i915_gem_obj_copy_ttm(struct drm_i915_gem_object *dst,
.interruptible = intr,
};
struct i915_refct_sgt *dst_rsgt;
struct dma_fence *copy_fence, *dep_fence;
struct dma_fence *copy_fence;
struct i915_deps deps;
int ret, shared_err;
@ -847,15 +787,12 @@ int i915_gem_obj_copy_ttm(struct drm_i915_gem_object *dst,
if (ret)
return ret;
dep_fence = i915_deps_to_fence(&deps, &ctx);
if (IS_ERR(dep_fence))
return PTR_ERR(dep_fence);
dst_rsgt = i915_ttm_resource_get_st(dst, dst_bo->resource);
copy_fence = __i915_ttm_move(src_bo, false, dst_bo->resource,
copy_fence = __i915_ttm_move(src_bo, &ctx, false, dst_bo->resource,
dst_bo->ttm, dst_rsgt, allow_accel,
dep_fence);
&deps);
i915_deps_fini(&deps);
i915_refct_sgt_put(dst_rsgt);
if (IS_ERR_OR_NULL(copy_fence))
return PTR_ERR_OR_ZERO(copy_fence);

17
drivers/gpu/drm/i915/gem/i915_gem_ttm_move.h
View file

@ -18,6 +18,23 @@ struct ttm_tt;
struct drm_i915_gem_object;
struct i915_refct_sgt;
/**
* struct i915_deps - Collect dependencies into a single dma-fence
* @single: Storage for pointer if the collection is a single fence.
* @fences: Allocated array of fence pointers if more than a single fence;
* otherwise points to the address of @single.
* @num_deps: Current number of dependency fences.
* @fences_size: Size of the @fences array in number of pointers.
* @gfp: Allocation mode.
*/
struct i915_deps {
struct dma_fence *single;
struct dma_fence **fences;
unsigned int num_deps;
unsigned int fences_size;
gfp_t gfp;
};
int i915_ttm_move_notify(struct ttm_buffer_object *bo);
I915_SELFTEST_DECLARE(void i915_ttm_migrate_set_failure_modes(bool gpu_migration,

24
drivers/gpu/drm/i915/gt/intel_migrate.c
View file

@ -404,7 +404,7 @@ static int emit_copy(struct i915_request *rq, int size)
int
intel_context_migrate_copy(struct intel_context *ce,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *src,
enum i915_cache_level src_cache_level,
bool src_is_lmem,
@ -431,8 +431,8 @@ intel_context_migrate_copy(struct intel_context *ce,
goto out_ce;
}
if (await) {
err = i915_request_await_dma_fence(rq, await);
if (deps) {
err = i915_request_await_deps(rq, deps);
if (err)
goto out_rq;
@ -442,7 +442,7 @@ intel_context_migrate_copy(struct intel_context *ce,
goto out_rq;
}
await = NULL;
deps = NULL;
}
/* The PTE updates + copy must not be interrupted. */
@ -525,7 +525,7 @@ static int emit_clear(struct i915_request *rq, int size, u32 value)
int
intel_context_migrate_clear(struct intel_context *ce,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *sg,
enum i915_cache_level cache_level,
bool is_lmem,
@ -550,8 +550,8 @@ intel_context_migrate_clear(struct intel_context *ce,
goto out_ce;
}
if (await) {
err = i915_request_await_dma_fence(rq, await);
if (deps) {
err = i915_request_await_deps(rq, deps);
if (err)
goto out_rq;
@ -561,7 +561,7 @@ intel_context_migrate_clear(struct intel_context *ce,
goto out_rq;
}
await = NULL;
deps = NULL;
}
/* The PTE updates + clear must not be interrupted. */
@ -599,7 +599,7 @@ intel_context_migrate_clear(struct intel_context *ce,
int intel_migrate_copy(struct intel_migrate *m,
struct i915_gem_ww_ctx *ww,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *src,
enum i915_cache_level src_cache_level,
bool src_is_lmem,
@ -624,7 +624,7 @@ int intel_migrate_copy(struct intel_migrate *m,
if (err)
goto out;
err = intel_context_migrate_copy(ce, await,
err = intel_context_migrate_copy(ce, deps,
src, src_cache_level, src_is_lmem,
dst, dst_cache_level, dst_is_lmem,
out);
@ -638,7 +638,7 @@ int intel_migrate_copy(struct intel_migrate *m,
int
intel_migrate_clear(struct intel_migrate *m,
struct i915_gem_ww_ctx *ww,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *sg,
enum i915_cache_level cache_level,
bool is_lmem,
@ -661,7 +661,7 @@ intel_migrate_clear(struct intel_migrate *m,
if (err)
goto out;
err = intel_context_migrate_clear(ce, await, sg, cache_level,
err = intel_context_migrate_clear(ce, deps, sg, cache_level,
is_lmem, value, out);
intel_context_unpin(ce);

9
drivers/gpu/drm/i915/gt/intel_migrate.h
View file

@ -11,6 +11,7 @@
#include "intel_migrate_types.h"
struct dma_fence;
struct i915_deps;
struct i915_request;
struct i915_gem_ww_ctx;
struct intel_gt;
@ -23,7 +24,7 @@ struct intel_context *intel_migrate_create_context(struct intel_migrate *m);
int intel_migrate_copy(struct intel_migrate *m,
struct i915_gem_ww_ctx *ww,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *src,
enum i915_cache_level src_cache_level,
bool src_is_lmem,
@ -33,7 +34,7 @@ int intel_migrate_copy(struct intel_migrate *m,
struct i915_request **out);
int intel_context_migrate_copy(struct intel_context *ce,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *src,
enum i915_cache_level src_cache_level,
bool src_is_lmem,
@ -45,7 +46,7 @@ int intel_context_migrate_copy(struct intel_context *ce,
int
intel_migrate_clear(struct intel_migrate *m,
struct i915_gem_ww_ctx *ww,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *sg,
enum i915_cache_level cache_level,
bool is_lmem,
@ -53,7 +54,7 @@ intel_migrate_clear(struct intel_migrate *m,
struct i915_request **out);
int
intel_context_migrate_clear(struct intel_context *ce,
struct dma_fence *await,
const struct i915_deps *deps,
struct scatterlist *sg,
enum i915_cache_level cache_level,
bool is_lmem,

22
drivers/gpu/drm/i915/i915_request.c
View file

@ -31,6 +31,7 @@
#include <linux/sched/signal.h>
#include "gem/i915_gem_context.h"
#include "gem/i915_gem_ttm_move.h"
#include "gt/intel_breadcrumbs.h"
#include "gt/intel_context.h"
#include "gt/intel_engine.h"
@ -1542,6 +1543,27 @@ i915_request_await_dma_fence(struct i915_request *rq, struct dma_fence *fence)
return 0;
}
/**
* i915_request_await_deps - set this request to (async) wait upon a struct
* i915_deps dma_fence collection
* @rq: request we are wishing to use
* @deps: The struct i915_deps containing the dependencies.
*
* Returns 0 if successful, negative error code on error.
*/
int i915_request_await_deps(struct i915_request *rq, const struct i915_deps *deps)
{
int i, err;
for (i = 0; i < deps->num_deps; ++i) {
err = i915_request_await_dma_fence(rq, deps->fences[i]);
if (err)
return err;
}
return 0;
}
/**
* i915_request_await_object - set this request to (async) wait upon a bo
* @to: request we are wishing to use

2
drivers/gpu/drm/i915/i915_request.h
View file

@ -47,6 +47,7 @@
struct drm_file;
struct drm_i915_gem_object;
struct drm_printer;
struct i915_deps;
struct i915_request;
#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
@ -411,6 +412,7 @@ int i915_request_await_object(struct i915_request *to,
bool write);
int i915_request_await_dma_fence(struct i915_request *rq,
struct dma_fence *fence);
int i915_request_await_deps(struct i915_request *rq, const struct i915_deps *deps);
int i915_request_await_execution(struct i915_request *rq,
struct dma_fence *fence);