drm/i915: Separate GEM context construction and registration to userspace

In later patches, it became apparent that userspace can see a partially
constructed GEM context and begin using it before it was ready, to much
hilarity. Close this window of opportunity by lifting the registration of
the context with userspace (the insertion of the context into the filp's
idr) to the very end of the CONTEXT_CREATE ioctl.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190321140711.11190-1-chris@chris-wilson.co.uk

4 files changed, 24 insertions, 9 deletions

diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
index 2e1db30af477..1f419fb094f4 100644
--- a/drivers/gpu/drm/i915/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
@@ -1713,7 +1713,7 @@ int i915_gem_huge_page_mock_selftests(void)
 	mkwrite_device_info(dev_priv)->ppgtt_size = 48;
 
 	mutex_lock(&dev_priv->drm.struct_mutex);
-	ppgtt = i915_ppgtt_create(dev_priv, ERR_PTR(-ENODEV));
+	ppgtt = i915_ppgtt_create(dev_priv);
 	if (IS_ERR(ppgtt)) {
 		err = PTR_ERR(ppgtt);
 		goto out_unlock;
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
index a172dbd9cb9e..ab2aa32fd019 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -76,7 +76,7 @@ static int live_nop_switch(void *arg)
 	}
 
 	for (n = 0; n < nctx; n++) {
-		ctx[n] = i915_gem_create_context(i915, file->driver_priv);
+		ctx[n] = live_context(i915, file);
 		if (IS_ERR(ctx[n])) {
 			err = PTR_ERR(ctx[n]);
 			goto out_unlock;
@@ -513,7 +513,7 @@ static int igt_ctx_exec(void *arg)
 		struct i915_gem_context *ctx;
 		unsigned int id;
 
-		ctx = i915_gem_create_context(i915, file->driver_priv);
+		ctx = live_context(i915, file);
 		if (IS_ERR(ctx)) {
 			err = PTR_ERR(ctx);
 			goto out_unlock;
@@ -962,7 +962,7 @@ __igt_ctx_sseu(struct drm_i915_private *i915,
 
 	mutex_lock(&i915->drm.struct_mutex);
 
-	ctx = i915_gem_create_context(i915, file->driver_priv);
+	ctx = live_context(i915, file);
 	if (IS_ERR(ctx)) {
 		ret = PTR_ERR(ctx);
 		goto out_unlock;
@@ -1072,7 +1072,7 @@ static int igt_ctx_readonly(void *arg)
 	if (err)
 		goto out_unlock;
 
-	ctx = i915_gem_create_context(i915, file->driver_priv);
+	ctx = live_context(i915, file);
 	if (IS_ERR(ctx)) {
 		err = PTR_ERR(ctx);
 		goto out_unlock;
@@ -1397,13 +1397,13 @@ static int igt_vm_isolation(void *arg)
 	if (err)
 		goto out_unlock;
 
-	ctx_a = i915_gem_create_context(i915, file->driver_priv);
+	ctx_a = live_context(i915, file);
 	if (IS_ERR(ctx_a)) {
 		err = PTR_ERR(ctx_a);
 		goto out_unlock;
 	}
 
-	ctx_b = i915_gem_create_context(i915, file->driver_priv);
+	ctx_b = live_context(i915, file);
 	if (IS_ERR(ctx_b)) {
 		err = PTR_ERR(ctx_b);
 		goto out_unlock;
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 826fd51c331e..01084f6b4fb7 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -1010,7 +1010,7 @@ static int exercise_ppgtt(struct drm_i915_private *dev_priv,
 		return PTR_ERR(file);
 
 	mutex_lock(&dev_priv->drm.struct_mutex);
-	ppgtt = i915_ppgtt_create(dev_priv, file->driver_priv);
+	ppgtt = i915_ppgtt_create(dev_priv);
 	if (IS_ERR(ppgtt)) {
 		err = PTR_ERR(ppgtt);
 		goto out_unlock;
diff --git a/drivers/gpu/drm/i915/selftests/mock_context.c b/drivers/gpu/drm/i915/selftests/mock_context.c
index 8efa6892c6cd..ad3875b01722 100644
--- a/drivers/gpu/drm/i915/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/selftests/mock_context.c
@@ -88,9 +88,24 @@ void mock_init_contexts(struct drm_i915_private *i915)
 struct i915_gem_context *
 live_context(struct drm_i915_private *i915, struct drm_file *file)
 {
+	struct i915_gem_context *ctx;
+	int err;
+
 	lockdep_assert_held(&i915->drm.struct_mutex);
 
-	return i915_gem_create_context(i915, file->driver_priv);
+	ctx = i915_gem_create_context(i915);
+	if (IS_ERR(ctx))
+		return ctx;
+
+	err = gem_context_register(ctx, file->driver_priv);
+	if (err)
+		goto err_ctx;
+
+	return ctx;
+
+err_ctx:
+	context_close(ctx);
+	return ERR_PTR(err);
 }
 
 struct i915_gem_context *