Re: [Intel-gfx] [PATCH 27/27] drm/i915/gem: Roll all of context creation together

On Mon, May 03, 2021 at 10:57:48AM -0500, Jason Ekstrand wrote:

Now that we have the whole engine set and VM at context creation time, we can just assign those fields instead of creating first and handling the VM and engines later. This lets us avoid creating useless VMs and engine sets and lets us get rid of the complex VM setting code.

Signed-off-by: Jason Ekstrand jason@jlekstrand.net

Ok here comes the cleanup around engine setup control flow and locking and all that.

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

So one thing I noticed that's still in the uapi bucket is that we now still have all the ctx->user_flags as mutable. I think especially persistence has a big impact on ctx cleanup, so would be nice if we can make that one invariant. Recoverable/no_error_capture less so, and bannable is kinda meh.

Did you look into how much it would be to lock these down too? We could then split the muttable ones out into a ctx->mutable_user_flags or so and only use atomic bitops for these.

Anyway the big items are the vm and engines, and that's taken care of now. -Daniel

---

drivers/gpu/drm/i915/gem/i915_gem_context.c | 159 ++++++------------ .../gpu/drm/i915/gem/selftests/mock_context.c | 33 ++-- 2 files changed, 64 insertions(+), 128 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c index 6e5828fe1a792..6bffb0e579b4e 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -1302,56 +1302,6 @@ static int __context_set_persistence(struct i915_gem_context *ctx, bool state) return 0; }

-static struct i915_gem_context * -__create_context(struct drm_i915_private *i915,

•  const struct i915_gem_proto_context *pc)
  

-{

• struct i915_gem_context *ctx;
• struct i915_gem_engines *e;
• int err;
• int i;
• ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
• if (!ctx)

• return ERR_PTR(-ENOMEM);
  

• kref_init(&ctx->ref);
• ctx->i915 = i915;
• ctx->sched = pc->sched;
• mutex_init(&ctx->mutex);
• INIT_LIST_HEAD(&ctx->link);
• spin_lock_init(&ctx->stale.lock);
• INIT_LIST_HEAD(&ctx->stale.engines);
• mutex_init(&ctx->engines_mutex);
• e = default_engines(ctx, pc->legacy_rcs_sseu);
• if (IS_ERR(e)) {

• err = PTR_ERR(e);
  

• goto err_free;
  

• }
• RCU_INIT_POINTER(ctx->engines, e);
• INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
• mutex_init(&ctx->lut_mutex);
• /* NB: Mark all slices as needing a remap so that when the context first

• * loads it will restore whatever remap state already exists. If there
  

• * is no remap info, it will be a NOP. */
  

• ctx->remap_slice = ALL_L3_SLICES(i915);
• ctx->user_flags = pc->user_flags;
• for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)

• ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
  

• return ctx;

-err_free:

• kfree(ctx);
• return ERR_PTR(err);

-}

static inline struct i915_gem_engines * __context_engines_await(const struct i915_gem_context *ctx, bool *user_engines) @@ -1395,86 +1345,77 @@ context_apply_all(struct i915_gem_context *ctx, i915_sw_fence_complete(&e->fence); }

-static void __apply_ppgtt(struct intel_context *ce, void *vm) -{

• i915_vm_put(ce->vm);
• ce->vm = i915_vm_get(vm);

-}

-static struct i915_address_space * -__set_ppgtt(struct i915_gem_context *ctx, struct i915_address_space *vm) -{

• struct i915_address_space *old;
• old = rcu_replace_pointer(ctx->vm,

• 		  i915_vm_open(vm),
  

• 		  lockdep_is_held(&ctx->mutex));
  

• GEM_BUG_ON(old && i915_vm_is_4lvl(vm) != i915_vm_is_4lvl(old));
• context_apply_all(ctx, __apply_ppgtt, vm);
• return old;

-}

-static void __assign_ppgtt(struct i915_gem_context *ctx,

• 	   struct i915_address_space *vm)
  

-{

• if (vm == rcu_access_pointer(ctx->vm))

• return;
  

• vm = __set_ppgtt(ctx, vm);
• if (vm)

• i915_vm_close(vm);
  

-}

static struct i915_gem_context * i915_gem_create_context(struct drm_i915_private *i915, const struct i915_gem_proto_context *pc) { struct i915_gem_context *ctx;

• int ret;

• struct i915_gem_engines *e;
• int err;
• int i;

• ctx = __create_context(i915, pc);
• if (IS_ERR(ctx))

• return ctx;
  

• ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
• if (!ctx)

• return ERR_PTR(-ENOMEM);
  
  

• if (pc->vm) {

• mutex_lock(&ctx->mutex);
  

• __assign_ppgtt(ctx, pc->vm);
  

• mutex_unlock(&ctx->mutex);
  

• }

• kref_init(&ctx->ref);
• ctx->i915 = i915;
• ctx->sched = pc->sched;
• mutex_init(&ctx->mutex);
• INIT_LIST_HEAD(&ctx->link);

• if (pc->num_user_engines >= 0) {

• struct i915_gem_engines *engines;
  

• spin_lock_init(&ctx->stale.lock);
• INIT_LIST_HEAD(&ctx->stale.engines);

• engines = user_engines(ctx, pc->num_user_engines,
  

• 		       pc->user_engines);
  

• if (IS_ERR(engines)) {
  

• 	context_close(ctx);
  

• 	return ERR_CAST(engines);
  

• }
  

• if (pc->vm)

• RCU_INIT_POINTER(ctx->vm, i915_vm_open(pc->vm));
  
  

• mutex_lock(&ctx->engines_mutex);
  

• mutex_init(&ctx->engines_mutex);
• if (pc->num_user_engines >= 0) { i915_gem_context_set_user_engines(ctx);

• engines = rcu_replace_pointer(ctx->engines, engines, 1);
  

• mutex_unlock(&ctx->engines_mutex);
  

• free_engines(engines);
  

• e = user_engines(ctx, pc->num_user_engines, pc->user_engines);
  

• } else {

• i915_gem_context_clear_user_engines(ctx);
  

• e = default_engines(ctx, pc->legacy_rcs_sseu);
  

  }

• if (IS_ERR(e)) {

• err = PTR_ERR(e);
  

• goto err_vm;
  

• }

• RCU_INIT_POINTER(ctx->engines, e);

• INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);

• mutex_init(&ctx->lut_mutex);

• /* NB: Mark all slices as needing a remap so that when the context first

• * loads it will restore whatever remap state already exists. If there
  

• * is no remap info, it will be a NOP. */
  

• ctx->remap_slice = ALL_L3_SLICES(i915);

• ctx->user_flags = pc->user_flags;

• for (i = 0; i < ARRAY_SIZE(ctx->hang_timestamp); i++)

• ctx->hang_timestamp[i] = jiffies - CONTEXT_FAST_HANG_JIFFIES;
  
  

  if (pc->single_timeline) {

• ret = drm_syncobj_create(&ctx->syncobj,
  

• err = drm_syncobj_create(&ctx->syncobj,
  		 DRM_SYNCOBJ_CREATE_SIGNALED,
  		 NULL);
  

• if (ret) {
  

• 	context_close(ctx);
  

• 	return ERR_PTR(ret);
  

• }
  

• if (err)
  

• 	goto err_engines;
  

  }

  trace_i915_context_create(ctx);

  return ctx;

+err_engines:

• free_engines(e);

+err_vm:

• if (ctx->vm)

• i915_vm_close(ctx->vm);
  

• kfree(ctx);
• return ERR_PTR(err);

}

static void init_contexts(struct i915_gem_contexts *gc) diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c index 500ef27ba4771..fee070df1c97b 100644 --- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c +++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c @@ -31,15 +31,6 @@ mock_context(struct drm_i915_private *i915,

i915_gem_context_set_persistence(ctx);

• mutex_init(&ctx->engines_mutex);
• e = default_engines(ctx, null_sseu);
• if (IS_ERR(e))

• goto err_free;
  

• RCU_INIT_POINTER(ctx->engines, e);
• INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
• mutex_init(&ctx->lut_mutex);
• if (name) { struct i915_ppgtt *ppgtt;

@@ -47,25 +38,29 @@ mock_context(struct drm_i915_private *i915,

ppgtt = mock_ppgtt(i915, name);
if (!ppgtt)

• 	goto err_put;
  

• mutex_lock(&ctx->mutex);
  

• __set_ppgtt(ctx, &ppgtt->vm);
  

• mutex_unlock(&ctx->mutex);
  

• 	goto err_free;
  
  

• ctx->vm = i915_vm_open(&ppgtt->vm);
  

  i915_vm_put(&ppgtt->vm); }

• mutex_init(&ctx->engines_mutex);

• e = default_engines(ctx, null_sseu);

• if (IS_ERR(e))

• goto err_vm;
  

• RCU_INIT_POINTER(ctx->engines, e);

• INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);

• mutex_init(&ctx->lut_mutex);

• return ctx;

+err_vm:

• if (ctx->vm)

• i915_vm_close(ctx->vm);
  

err_free: kfree(ctx); return NULL;

-err_put:

• i915_gem_context_set_closed(ctx);
• i915_gem_context_put(ctx);
• return NULL;

}

void mock_context_close(struct i915_gem_context *ctx)

2.31.1

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