[Intel-gfx] [PATCH 9/9] drm/i915: Split out intel_context_create_user

[Daniel Vetter <daniel.vetter@ffwll.ch>]

There's quite a fundamental difference between userspace contexts, and
kernel contexts. Latter all share intel_gt->vm, former get their vm
from gem_ctx->vm (on full ppgtt at least).

By splitting context creation for userspace from kernel-internal ones
we can make this all a bit more strict and WARN_ON if there's a vm
already set in intel_context_set_gem().

All this is only possible because gem_ctx cannot chance their VM
anymore since

        commit ccbc1b97948ab671335e950271e39766729736c3
        Author: Jason Ekstrand <jason@jlekstrand.net>
        Date:   Thu Jul 8 10:48:30 2021 -0500

            drm/i915/gem: Don't allow changing the VM on running contexts (v4)

Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
---
 drivers/gpu/drm/i915/gem/i915_gem_context.c   |  6 ++---
 .../gpu/drm/i915/gem/i915_gem_execbuffer.c    |  4 +++-
 .../gpu/drm/i915/gem/selftests/mock_context.c |  2 +-
 drivers/gpu/drm/i915/gt/intel_context.c       | 22 +++++++++++++++++--
 drivers/gpu/drm/i915/gt/intel_context.h       |  2 ++
 5 files changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
index 2f3cc73d4710..13358e6749d9 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
@@ -746,7 +746,7 @@ static int intel_context_set_gem(struct intel_context *ce,
 
 	ce->ring_size = SZ_16K;
 
-	i915_vm_put(ce->vm);
+	WARN_ON(ce->vm);
 	ce->vm = i915_gem_context_get_eb_vm(ctx);
 
 	if (ctx->sched.priority >= I915_PRIORITY_NORMAL &&
@@ -856,7 +856,7 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx,
 		GEM_BUG_ON(engine->legacy_idx >= I915_NUM_ENGINES);
 		GEM_BUG_ON(e->engines[engine->legacy_idx]);
 
-		ce = intel_context_create(engine);
+		ce = intel_context_create_user(engine);
 		if (IS_ERR(ce)) {
 			err = ERR_CAST(ce);
 			goto free_engines;
@@ -897,7 +897,7 @@ static struct i915_gem_engines *user_engines(struct i915_gem_context *ctx,
 
 		switch (pe[n].type) {
 		case I915_GEM_ENGINE_TYPE_PHYSICAL:
-			ce = intel_context_create(pe[n].engine);
+			ce = intel_context_create_user(pe[n].engine);
 			break;
 
 		case I915_GEM_ENGINE_TYPE_BALANCED:
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
index bdf2b5785a81..54de94433365 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
@@ -30,15 +30,17 @@
 
 struct eb_vma {
 	struct i915_vma *vma;
+	struct drm_i915_gem_object *obj;
 	unsigned int flags;
 
+	u32 handle;
+
 	/** This vma's place in the execbuf reservation list */
 	struct drm_i915_gem_exec_object2 *exec;
 	struct list_head bind_link;
 	struct list_head reloc_link;
 
 	struct hlist_node node;
-	u32 handle;
 };
 
 enum {
diff --git a/drivers/gpu/drm/i915/gem/selftests/mock_context.c b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
index fee070df1c97..e5efda1058a3 100644
--- a/drivers/gpu/drm/i915/gem/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/gem/selftests/mock_context.c
@@ -124,7 +124,7 @@ live_context_for_engine(struct intel_engine_cs *engine, struct file *file)
 		return ctx;
 	}
 
-	ce = intel_context_create(engine);
+	ce = intel_context_create_user(engine);
 	if (IS_ERR(ce)) {
 		__free_engines(engines, 0);
 		return ERR_CAST(ce);
diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c
index 745e84c72c90..9e33efb594dd 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.c
+++ b/drivers/gpu/drm/i915/gt/intel_context.c
@@ -34,6 +34,23 @@ void intel_context_free(struct intel_context *ce)
 	call_rcu(&ce->rcu, rcu_context_free);
 }
 
+/* for user contexts, callers must set ce->vm correctly */
+struct intel_context *
+intel_context_create_user(struct intel_engine_cs *engine)
+{
+	struct intel_context *ce;
+
+	ce = intel_context_alloc();
+	if (!ce)
+		return ERR_PTR(-ENOMEM);
+
+	intel_context_init(ce, engine);
+
+	trace_intel_context_create(ce);
+	return ce;
+}
+
+/* for kernel-internal users only, sets ce->vm to intel_gt.vm */
 struct intel_context *
 intel_context_create(struct intel_engine_cs *engine)
 {
@@ -44,6 +61,8 @@ intel_context_create(struct intel_engine_cs *engine)
 		return ERR_PTR(-ENOMEM);
 
 	intel_context_init(ce, engine);
+	ce->vm = i915_vm_get(engine->gt->vm);
+
 	trace_intel_context_create(ce);
 	return ce;
 }
@@ -368,6 +387,7 @@ static int sw_fence_dummy_notify(struct i915_sw_fence *sf,
 	return NOTIFY_DONE;
 }
 
+/* callers must set ce->vm for user or kernel vm as needed */
 void
 intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 {
@@ -384,8 +404,6 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine)
 
 	ewma_runtime_init(&ce->runtime.avg);
 
-	ce->vm = i915_vm_get(engine->gt->vm);
-
 	/* NB ce->signal_link/lock is used under RCU */
 	spin_lock_init(&ce->signal_lock);
 	INIT_LIST_HEAD(&ce->signals);
diff --git a/drivers/gpu/drm/i915/gt/intel_context.h b/drivers/gpu/drm/i915/gt/intel_context.h
index c41098950746..a80018d53a36 100644
--- a/drivers/gpu/drm/i915/gt/intel_context.h
+++ b/drivers/gpu/drm/i915/gt/intel_context.h
@@ -34,6 +34,8 @@ void intel_context_fini(struct intel_context *ce);
 void i915_context_module_exit(void);
 int i915_context_module_init(void);
 
+struct intel_context *
+intel_context_create_user(struct intel_engine_cs *engine);
 struct intel_context *
 intel_context_create(struct intel_engine_cs *engine);
 
-- 
2.32.0