[34/47] drm/i915: Create/destroy VM (ppGTT) for use with contexts

Submitted by Chris Wilson on Feb. 8, 2019, 8:52 p.m.

Details

Message ID 20190208205259.2450-34-chris@chris-wilson.co.uk
State New
Series "Series without cover letter"
Headers show

Commit Message

Chris Wilson Feb. 8, 2019, 8:52 p.m.
In preparation to making the ppGTT binding for a context explicit (to
facilitate reusing the same ppGTT between different contexts), allow the
user to create and destroy named ppGTT.

v2: Replace global barrier for swapping over the ppgtt and tlbs with a
local context barrier (Tvrtko)
v3: serialise with struct_mutex; it's lazy but required dammit

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/i915_drv.c               |   2 +
 drivers/gpu/drm/i915/i915_drv.h               |   3 +
 drivers/gpu/drm/i915/i915_gem_context.c       | 254 +++++++++++++++++-
 drivers/gpu/drm/i915/i915_gem_context.h       |   5 +
 drivers/gpu/drm/i915/i915_gem_gtt.c           |  17 +-
 drivers/gpu/drm/i915/i915_gem_gtt.h           |  16 +-
 drivers/gpu/drm/i915/selftests/huge_pages.c   |   1 -
 .../gpu/drm/i915/selftests/i915_gem_context.c | 239 ++++++++++++----
 drivers/gpu/drm/i915/selftests/i915_gem_gtt.c |   1 -
 drivers/gpu/drm/i915/selftests/mock_context.c |   8 +-
 include/uapi/drm/i915_drm.h                   |  35 +++
 11 files changed, 510 insertions(+), 71 deletions(-)

Patch hide | download patch | download mbox

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index ea7504bce668..eee1cd115385 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -3007,6 +3007,8 @@  static const struct drm_ioctl_desc i915_ioctls[] = {
 	DRM_IOCTL_DEF_DRV(I915_PERF_ADD_CONFIG, i915_perf_add_config_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_PERF_REMOVE_CONFIG, i915_perf_remove_config_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
 	DRM_IOCTL_DEF_DRV(I915_QUERY, i915_query_ioctl, DRM_UNLOCKED|DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_GEM_VM_CREATE, i915_gem_vm_create_ioctl, DRM_RENDER_ALLOW),
+	DRM_IOCTL_DEF_DRV(I915_GEM_VM_DESTROY, i915_gem_vm_destroy_ioctl, DRM_RENDER_ALLOW),
 };
 
 static struct drm_driver driver = {
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 02dd0316cd5f..2077f9ac5a6a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -217,6 +217,9 @@  struct drm_i915_file_private {
 	} mm;
 	struct idr context_idr;
 
+	struct mutex vm_lock;
+	struct idr vm_idr;
+
 	unsigned int bsd_engine;
 
 /*
diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
index c3f41f501276..dd49b1ef3ff2 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/i915_gem_context.c
@@ -110,6 +110,8 @@  static void lut_close(struct i915_gem_context *ctx)
 		struct i915_vma *vma = rcu_dereference_raw(*slot);
 
 		radix_tree_iter_delete(&ctx->handles_vma, &iter, slot);
+
+		vma->open_count--;
 		__i915_gem_object_release_unless_active(vma->obj);
 	}
 	rcu_read_unlock();
@@ -293,7 +295,7 @@  static void context_close(struct i915_gem_context *ctx)
 	 */
 	lut_close(ctx);
 	if (ctx->ppgtt)
-		i915_ppgtt_close(&ctx->ppgtt->vm);
+		i915_ppgtt_close(ctx->ppgtt);
 
 	ctx->file_priv = ERR_PTR(-EBADF);
 	i915_gem_context_put(ctx);
@@ -425,6 +427,32 @@  static void __destroy_hw_context(struct i915_gem_context *ctx,
 	context_close(ctx);
 }
 
+static struct i915_hw_ppgtt *
+__set_ppgtt(struct i915_gem_context *ctx, struct i915_hw_ppgtt *ppgtt)
+{
+	struct i915_hw_ppgtt *old = ctx->ppgtt;
+
+	i915_ppgtt_open(ppgtt);
+	ctx->ppgtt = i915_ppgtt_get(ppgtt);
+
+	ctx->desc_template = default_desc_template(ctx->i915, ppgtt);
+
+	return old;
+}
+
+static void __assign_ppgtt(struct i915_gem_context *ctx,
+			   struct i915_hw_ppgtt *ppgtt)
+{
+	if (ppgtt == ctx->ppgtt)
+		return;
+
+	ppgtt = __set_ppgtt(ctx, ppgtt);
+	if (ppgtt) {
+		i915_ppgtt_close(ppgtt);
+		i915_ppgtt_put(ppgtt);
+	}
+}
+
 static struct i915_gem_context *
 i915_gem_create_context(struct drm_i915_private *dev_priv,
 			struct drm_i915_file_private *file_priv)
@@ -451,8 +479,8 @@  i915_gem_create_context(struct drm_i915_private *dev_priv,
 			return ERR_CAST(ppgtt);
 		}
 
-		ctx->ppgtt = ppgtt;
-		ctx->desc_template = default_desc_template(dev_priv, ppgtt);
+		__assign_ppgtt(ctx, ppgtt);
+		i915_ppgtt_put(ppgtt);
 	}
 
 	trace_i915_context_create(ctx);
@@ -633,19 +661,29 @@  static int context_idr_cleanup(int id, void *p, void *data)
 	return 0;
 }
 
+static int vm_idr_cleanup(int id, void *p, void *data)
+{
+	i915_ppgtt_put(p);
+	return 0;
+}
+
 int i915_gem_context_open(struct drm_i915_private *i915,
 			  struct drm_file *file)
 {
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct i915_gem_context *ctx;
 
+	mutex_init(&file_priv->vm_lock);
+
 	idr_init(&file_priv->context_idr);
+	idr_init_base(&file_priv->vm_idr, 1);
 
 	mutex_lock(&i915->drm.struct_mutex);
 	ctx = i915_gem_create_context(i915, file_priv);
 	mutex_unlock(&i915->drm.struct_mutex);
 	if (IS_ERR(ctx)) {
 		idr_destroy(&file_priv->context_idr);
+		idr_destroy(&file_priv->vm_idr);
 		return PTR_ERR(ctx);
 	}
 
@@ -662,6 +700,89 @@  void i915_gem_context_close(struct drm_file *file)
 
 	idr_for_each(&file_priv->context_idr, context_idr_cleanup, NULL);
 	idr_destroy(&file_priv->context_idr);
+
+	idr_for_each(&file_priv->vm_idr, vm_idr_cleanup, NULL);
+	idr_destroy(&file_priv->vm_idr);
+
+	mutex_destroy(&file_priv->vm_lock);
+}
+
+int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
+			     struct drm_file *file)
+{
+	struct drm_i915_private *i915 = to_i915(dev);
+	struct drm_i915_gem_vm_control *args = data;
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct i915_hw_ppgtt *ppgtt;
+	int err;
+
+	if (!HAS_FULL_PPGTT(i915))
+		return -ENODEV;
+
+	if (args->flags)
+		return -EINVAL;
+
+	if (args->extensions)
+		return -EINVAL;
+
+	ppgtt = i915_ppgtt_create(i915, file_priv);
+	if (IS_ERR(ppgtt))
+		return PTR_ERR(ppgtt);
+
+	err = mutex_lock_interruptible(&file_priv->vm_lock);
+	if (err)
+		goto err_put;
+
+	err = idr_alloc(&file_priv->vm_idr, ppgtt, 0, 0, GFP_KERNEL);
+	mutex_unlock(&file_priv->vm_lock);
+	if (err < 0)
+		goto err_put;
+
+	GEM_BUG_ON(err == 0); /* reserved for default/unassigned ppgtt */
+	ppgtt->user_handle = err;
+	args->id = err;
+	return 0;
+
+err_put:
+	i915_ppgtt_put(ppgtt);
+	return err;
+}
+
+int i915_gem_vm_destroy_ioctl(struct drm_device *dev, void *data,
+			      struct drm_file *file)
+{
+	struct drm_i915_file_private *file_priv = file->driver_priv;
+	struct drm_i915_gem_vm_control *args = data;
+	struct i915_hw_ppgtt *ppgtt;
+	int err;
+	u32 id;
+
+	if (args->flags)
+		return -EINVAL;
+
+	if (args->extensions)
+		return -EINVAL;
+
+	id = args->id;
+	if (!id)
+		return -ENOENT;
+
+	err = mutex_lock_interruptible(&file_priv->vm_lock);
+	if (err)
+		return err;
+
+	ppgtt = idr_remove(&file_priv->vm_idr, id);
+	if (ppgtt) {
+		GEM_BUG_ON(!ppgtt->user_handle);
+		ppgtt->user_handle = 0;
+	}
+
+	mutex_unlock(&file_priv->vm_lock);
+	if (!ppgtt)
+		return -ENOENT;
+
+	i915_ppgtt_put(ppgtt);
+	return 0;
 }
 
 static struct i915_request *
@@ -809,6 +930,120 @@  int i915_gem_switch_to_kernel_context(struct drm_i915_private *i915,
 	return 0;
 }
 
+static int get_ppgtt(struct i915_gem_context *ctx,
+		     struct drm_i915_gem_context_param *args)
+{
+	struct drm_i915_file_private *file_priv = ctx->file_priv;
+	struct i915_hw_ppgtt *ppgtt;
+	int ret;
+
+	if (!ctx->ppgtt)
+		return -ENODEV;
+
+	/* XXX rcu acquire? */
+	ret = mutex_lock_interruptible(&ctx->i915->drm.struct_mutex);
+	if (ret)
+		return ret;
+
+	ppgtt = i915_ppgtt_get(ctx->ppgtt);
+	mutex_unlock(&ctx->i915->drm.struct_mutex);
+
+	ret = mutex_lock_interruptible(&file_priv->vm_lock);
+	if (ret)
+		goto err_put;
+
+	if (!ppgtt->user_handle) {
+		ret = idr_alloc(&file_priv->vm_idr, ppgtt, 0, 0, GFP_KERNEL);
+		GEM_BUG_ON(!ret);
+		if (ret < 0)
+			goto err_unlock;
+
+		ppgtt->user_handle = ret;
+		i915_ppgtt_get(ppgtt);
+	}
+
+	args->size = 0;
+	args->value = ppgtt->user_handle;
+
+	ret = 0;
+err_unlock:
+	mutex_unlock(&file_priv->vm_lock);
+err_put:
+	i915_ppgtt_put(ppgtt);
+	return ret;
+}
+
+static void set_ppgtt_barrier(void *data)
+{
+	struct i915_hw_ppgtt *old = data;
+
+	i915_ppgtt_close(old);
+	i915_ppgtt_put(old);
+}
+
+static int set_ppgtt(struct i915_gem_context *ctx,
+		     struct drm_i915_gem_context_param *args)
+{
+	struct drm_i915_file_private *file_priv = ctx->file_priv;
+	struct i915_hw_ppgtt *ppgtt, *old;
+	int err;
+
+	if (args->size)
+		return -EINVAL;
+
+	if (upper_32_bits(args->value))
+		return -EINVAL;
+
+	if (!ctx->ppgtt)
+		return -ENODEV;
+
+	err = mutex_lock_interruptible(&file_priv->vm_lock);
+	if (err)
+		return err;
+
+	ppgtt = idr_find(&file_priv->vm_idr, args->value);
+	if (ppgtt) {
+		GEM_BUG_ON(ppgtt->user_handle != args->value);
+		i915_ppgtt_get(ppgtt);
+	}
+	mutex_unlock(&file_priv->vm_lock);
+	if (!ppgtt)
+		return -ENOENT;
+
+	err = mutex_lock_interruptible(&ctx->i915->drm.struct_mutex);
+	if (err)
+		goto out;
+
+	if (ppgtt == ctx->ppgtt)
+		goto unlock;
+
+	/* Teardown the existing obj:vma cache, it will have to be rebuilt. */
+	lut_close(ctx);
+
+	old = __set_ppgtt(ctx, ppgtt);
+
+	/*
+	 * We need to flush any requests using the current ppgtt before
+	 * we release it as the requests do not hold a reference themselves,
+	 * only indirectly through the context.
+	 */
+	err = context_barrier_task(ctx, -1, set_ppgtt_barrier, old);
+	if (err) {
+		ctx->ppgtt = old;
+		ctx->desc_template = default_desc_template(ctx->i915, old);
+
+		i915_ppgtt_close(ppgtt);
+		i915_ppgtt_put(ppgtt);
+	}
+
+unlock:
+	mutex_unlock(&ctx->i915->drm.struct_mutex);
+
+out:
+	i915_ppgtt_put(ppgtt);
+	return err;
+}
+
 static bool client_is_banned(struct drm_i915_file_private *file_priv)
 {
 	return atomic_read(&file_priv->ban_score) >= I915_CLIENT_SCORE_BANNED;
@@ -979,6 +1214,9 @@  int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
 	case I915_CONTEXT_PARAM_SSEU:
 		ret = get_sseu(ctx, args);
 		break;
+	case I915_CONTEXT_PARAM_VM:
+		ret = get_ppgtt(ctx, args);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -1276,9 +1514,6 @@  int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 		return -ENOENT;
 
 	switch (args->param) {
-	case I915_CONTEXT_PARAM_BAN_PERIOD:
-		ret = -EINVAL;
-		break;
 	case I915_CONTEXT_PARAM_NO_ZEROMAP:
 		if (args->size)
 			ret = -EINVAL;
@@ -1325,9 +1560,16 @@  int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
 					I915_USER_PRIORITY(priority);
 		}
 		break;
+
 	case I915_CONTEXT_PARAM_SSEU:
 		ret = set_sseu(ctx, args);
 		break;
+
+	case I915_CONTEXT_PARAM_VM:
+		ret = set_ppgtt(ctx, args);
+		break;
+
+	case I915_CONTEXT_PARAM_BAN_PERIOD:
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
index ab89c7501408..c5a6cb10dbda 100644
--- a/drivers/gpu/drm/i915/i915_gem_context.h
+++ b/drivers/gpu/drm/i915/i915_gem_context.h
@@ -365,6 +365,11 @@  void i915_gem_context_release(struct kref *ctx_ref);
 struct i915_gem_context *
 i915_gem_context_create_gvt(struct drm_device *dev);
 
+int i915_gem_vm_create_ioctl(struct drm_device *dev, void *data,
+			     struct drm_file *file);
+int i915_gem_vm_destroy_ioctl(struct drm_device *dev, void *data,
+			      struct drm_file *file);
+
 int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 				  struct drm_file *file);
 int i915_gem_context_destroy_ioctl(struct drm_device *dev, void *data,
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index d646d37eec2f..ccf10306b1f5 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -2103,10 +2103,21 @@  i915_ppgtt_create(struct drm_i915_private *i915,
 	return ppgtt;
 }
 
-void i915_ppgtt_close(struct i915_address_space *vm)
+void i915_ppgtt_open(struct i915_hw_ppgtt *ppgtt)
 {
-	GEM_BUG_ON(vm->closed);
-	vm->closed = true;
+	GEM_BUG_ON(ppgtt->vm.closed);
+
+	ppgtt->open_count++;
+}
+
+void i915_ppgtt_close(struct i915_hw_ppgtt *ppgtt)
+{
+	GEM_BUG_ON(!ppgtt->open_count);
+	if (--ppgtt->open_count)
+		return;
+
+	GEM_BUG_ON(ppgtt->vm.closed);
+	ppgtt->vm.closed = true;
 }
 
 static void ppgtt_destroy_vma(struct i915_address_space *vm)
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
index 03ade71b8d9a..bb750318f52a 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
@@ -391,11 +391,15 @@  struct i915_hw_ppgtt {
 	struct kref ref;
 
 	unsigned long pd_dirty_rings;
+	unsigned int open_count;
+
 	union {
 		struct i915_pml4 pml4;		/* GEN8+ & 48b PPGTT */
 		struct i915_page_directory_pointer pdp;	/* GEN8+ */
 		struct i915_page_directory pd;		/* GEN6-7 */
 	};
+
+	u32 user_handle;
 };
 
 struct gen6_hw_ppgtt {
@@ -606,12 +610,16 @@  int i915_ppgtt_init_hw(struct drm_i915_private *dev_priv);
 void i915_ppgtt_release(struct kref *kref);
 struct i915_hw_ppgtt *i915_ppgtt_create(struct drm_i915_private *dev_priv,
 					struct drm_i915_file_private *fpriv);
-void i915_ppgtt_close(struct i915_address_space *vm);
-static inline void i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)
+
+void i915_ppgtt_open(struct i915_hw_ppgtt *ppgtt);
+void i915_ppgtt_close(struct i915_hw_ppgtt *ppgtt);
+
+static inline struct i915_hw_ppgtt *i915_ppgtt_get(struct i915_hw_ppgtt *ppgtt)
 {
-	if (ppgtt)
-		kref_get(&ppgtt->ref);
+	kref_get(&ppgtt->ref);
+	return ppgtt;
 }
+
 static inline void i915_ppgtt_put(struct i915_hw_ppgtt *ppgtt)
 {
 	if (ppgtt)
diff --git a/drivers/gpu/drm/i915/selftests/huge_pages.c b/drivers/gpu/drm/i915/selftests/huge_pages.c
index a9a2fa35876f..a7ee8e97bcee 100644
--- a/drivers/gpu/drm/i915/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/selftests/huge_pages.c
@@ -1734,7 +1734,6 @@  int i915_gem_huge_page_mock_selftests(void)
 	err = i915_subtests(tests, ppgtt);
 
 out_close:
-	i915_ppgtt_close(&ppgtt->vm);
 	i915_ppgtt_put(ppgtt);
 
 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 4b6df1c55345..a76a4f6f67e4 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_context.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_context.c
@@ -372,7 +372,8 @@  static int cpu_fill(struct drm_i915_gem_object *obj, u32 value)
 	return 0;
 }
 
-static int cpu_check(struct drm_i915_gem_object *obj, unsigned int max)
+static noinline int cpu_check(struct drm_i915_gem_object *obj,
+			      unsigned int idx, unsigned int max)
 {
 	unsigned int n, m, needs_flush;
 	int err;
@@ -390,8 +391,10 @@  static int cpu_check(struct drm_i915_gem_object *obj, unsigned int max)
 
 		for (m = 0; m < max; m++) {
 			if (map[m] != m) {
-				pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
-				       n, m, map[m], m);
+				pr_err("%pS: Invalid value at object %d page %d/%ld, offset %d/%d: found %x expected %x\n",
+				       __builtin_return_address(0), idx,
+				       n, real_page_count(obj), m, max,
+				       map[m], m);
 				err = -EINVAL;
 				goto out_unmap;
 			}
@@ -399,8 +402,9 @@  static int cpu_check(struct drm_i915_gem_object *obj, unsigned int max)
 
 		for (; m < DW_PER_PAGE; m++) {
 			if (map[m] != STACK_MAGIC) {
-				pr_err("Invalid value at page %d, offset %d: found %x expected %x\n",
-				       n, m, map[m], STACK_MAGIC);
+				pr_err("%pS: Invalid value at object %d page %d, offset %d: found %x expected %x (uninitialised)\n",
+				       __builtin_return_address(0), idx, n, m,
+				       map[m], STACK_MAGIC);
 				err = -EINVAL;
 				goto out_unmap;
 			}
@@ -478,12 +482,8 @@  static unsigned long max_dwords(struct drm_i915_gem_object *obj)
 static int igt_ctx_exec(void *arg)
 {
 	struct drm_i915_private *i915 = arg;
-	struct drm_i915_gem_object *obj = NULL;
-	unsigned long ncontexts, ndwords, dw;
-	struct igt_live_test t;
-	struct drm_file *file;
-	IGT_TIMEOUT(end_time);
-	LIST_HEAD(objects);
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
 	int err = -ENODEV;
 
 	/*
@@ -495,38 +495,42 @@  static int igt_ctx_exec(void *arg)
 	if (!DRIVER_CAPS(i915)->has_logical_contexts)
 		return 0;
 
-	file = mock_file(i915);
-	if (IS_ERR(file))
-		return PTR_ERR(file);
+	for_each_engine(engine, i915, id) {
+		struct drm_i915_gem_object *obj = NULL;
+		unsigned long ncontexts, ndwords, dw;
+		struct igt_live_test t;
+		struct drm_file *file;
+		IGT_TIMEOUT(end_time);
+		LIST_HEAD(objects);
 
-	mutex_lock(&i915->drm.struct_mutex);
+		if (!intel_engine_can_store_dword(engine))
+			continue;
 
-	err = igt_live_test_begin(&t, i915, __func__, "");
-	if (err)
-		goto out_unlock;
+		if (!engine->context_size)
+			continue; /* No logical context support in HW */
 
-	ncontexts = 0;
-	ndwords = 0;
-	dw = 0;
-	while (!time_after(jiffies, end_time)) {
-		struct intel_engine_cs *engine;
-		struct i915_gem_context *ctx;
-		unsigned int id;
+		file = mock_file(i915);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
 
-		ctx = i915_gem_create_context(i915, file->driver_priv);
-		if (IS_ERR(ctx)) {
-			err = PTR_ERR(ctx);
+		mutex_lock(&i915->drm.struct_mutex);
+
+		err = igt_live_test_begin(&t, i915, __func__, engine->name);
+		if (err)
 			goto out_unlock;
-		}
 
-		for_each_engine(engine, i915, id) {
+		ncontexts = 0;
+		ndwords = 0;
+		dw = 0;
+		while (!time_after(jiffies, end_time)) {
+			struct i915_gem_context *ctx;
 			intel_wakeref_t wakeref;
 
-			if (!engine->context_size)
-				continue; /* No logical context support in HW */
-
-			if (!intel_engine_can_store_dword(engine))
-				continue;
+			ctx = i915_gem_create_context(i915, file->driver_priv);
+			if (IS_ERR(ctx)) {
+				err = PTR_ERR(ctx);
+				goto out_unlock;
+			}
 
 			if (!obj) {
 				obj = create_test_object(ctx, file, &objects);
@@ -536,7 +540,6 @@  static int igt_ctx_exec(void *arg)
 				}
 			}
 
-			err = 0;
 			with_intel_runtime_pm(i915, wakeref)
 				err = gpu_fill(obj, ctx, engine, dw);
 			if (err) {
@@ -551,32 +554,158 @@  static int igt_ctx_exec(void *arg)
 				obj = NULL;
 				dw = 0;
 			}
+
 			ndwords++;
+			ncontexts++;
 		}
-		ncontexts++;
+
+		pr_info("Submitted %lu contexts to %s, filling %lu dwords\n",
+			ncontexts, engine->name, ndwords);
+
+		ncontexts = dw = 0;
+		list_for_each_entry(obj, &objects, st_link) {
+			unsigned int rem =
+				min_t(unsigned int, ndwords - dw, max_dwords(obj));
+
+			err = cpu_check(obj, ncontexts++, rem);
+			if (err)
+				break;
+
+			dw += rem;
+		}
+
+out_unlock:
+		if (igt_live_test_end(&t))
+			err = -EIO;
+		mutex_unlock(&i915->drm.struct_mutex);
+
+		mock_file_free(i915, file);
+		if (err)
+			return err;
 	}
-	pr_info("Submitted %lu contexts (across %u engines), filling %lu dwords\n",
-		ncontexts, RUNTIME_INFO(i915)->num_rings, ndwords);
 
-	dw = 0;
-	list_for_each_entry(obj, &objects, st_link) {
-		unsigned int rem =
-			min_t(unsigned int, ndwords - dw, max_dwords(obj));
+	return 0;
+}
+
+static int igt_shared_ctx_exec(void *arg)
+{
+	struct drm_i915_private *i915 = arg;
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+	int err = -ENODEV;
+
+	/*
+	 * Create a few different contexts with the same mm and write
+	 * through each ctx using the GPU making sure those writes end
+	 * up in the expected pages of our obj.
+	 */
+
+	for_each_engine(engine, i915, id) {
+		unsigned long ncontexts, ndwords, dw;
+		struct drm_i915_gem_object *obj = NULL;
+		struct i915_gem_context *ctx = NULL;
+		struct i915_gem_context *parent;
+		struct igt_live_test t;
+		struct drm_file *file;
+		IGT_TIMEOUT(end_time);
+		LIST_HEAD(objects);
 
-		err = cpu_check(obj, rem);
+		if (!intel_engine_can_store_dword(engine))
+			continue;
+
+		file = mock_file(i915);
+		if (IS_ERR(file))
+			return PTR_ERR(file);
+
+		mutex_lock(&i915->drm.struct_mutex);
+
+		err = igt_live_test_begin(&t, i915, __func__, engine->name);
 		if (err)
-			break;
+			goto out_unlock;
 
-		dw += rem;
-	}
+		parent = i915_gem_create_context(i915, file->driver_priv);
+		if (IS_ERR(parent)) {
+			err = PTR_ERR(parent);
+			if (err == -ENODEV) /* no logical ctx support */
+				err = 0;
+			goto out_unlock;
+		}
+
+		if (!parent->ppgtt) {
+			err = 0;
+			goto out_unlock;
+		}
+
+		ncontexts = 0;
+		ndwords = 0;
+		dw = 0;
+		while (!time_after(jiffies, end_time)) {
+			intel_wakeref_t wakeref;
+
+			if (ctx)
+				__destroy_hw_context(ctx, file->driver_priv);
+
+			ctx = i915_gem_create_context(i915, file->driver_priv);
+			if (IS_ERR(ctx)) {
+				err = PTR_ERR(ctx);
+				goto out_unlock;
+			}
+
+			__assign_ppgtt(ctx, parent->ppgtt);
+
+			if (!obj) {
+				obj = create_test_object(parent, file, &objects);
+				if (IS_ERR(obj)) {
+					err = PTR_ERR(obj);
+					goto out_unlock;
+				}
+			}
+
+			err = 0;
+			with_intel_runtime_pm(i915, wakeref)
+				err = gpu_fill(obj, ctx, engine, dw);
+			if (err) {
+				pr_err("Failed to fill dword %lu [%lu/%lu] with gpu (%s) in ctx %u [full-ppgtt? %s], err=%d\n",
+				       ndwords, dw, max_dwords(obj),
+				       engine->name, ctx->hw_id,
+				       yesno(!!ctx->ppgtt), err);
+				goto out_unlock;
+			}
+
+			if (++dw == max_dwords(obj)) {
+				obj = NULL;
+				dw = 0;
+			}
+
+			ndwords++;
+			ncontexts++;
+		}
+		pr_info("Submitted %lu contexts to %s, filling %lu dwords\n",
+			ncontexts, engine->name, ndwords);
+
+		ncontexts = dw = 0;
+		list_for_each_entry(obj, &objects, st_link) {
+			unsigned int rem =
+				min_t(unsigned int, ndwords - dw, max_dwords(obj));
+
+			err = cpu_check(obj, ncontexts++, rem);
+			if (err)
+				break;
+
+			dw += rem;
+		}
 
 out_unlock:
-	if (igt_live_test_end(&t))
-		err = -EIO;
-	mutex_unlock(&i915->drm.struct_mutex);
+		if (igt_live_test_end(&t))
+			err = -EIO;
+		mutex_unlock(&i915->drm.struct_mutex);
 
-	mock_file_free(i915, file);
-	return err;
+		mock_file_free(i915, file);
+		if (err)
+			return err;
+	}
+
+	return 0;
 }
 
 static struct i915_vma *rpcs_query_batch(struct i915_vma *vma)
@@ -1048,7 +1177,7 @@  static int igt_ctx_readonly(void *arg)
 	struct drm_i915_gem_object *obj = NULL;
 	struct i915_gem_context *ctx;
 	struct i915_hw_ppgtt *ppgtt;
-	unsigned long ndwords, dw;
+	unsigned long idx, ndwords, dw;
 	struct igt_live_test t;
 	struct drm_file *file;
 	I915_RND_STATE(prng);
@@ -1129,6 +1258,7 @@  static int igt_ctx_readonly(void *arg)
 		ndwords, RUNTIME_INFO(i915)->num_rings);
 
 	dw = 0;
+	idx = 0;
 	list_for_each_entry(obj, &objects, st_link) {
 		unsigned int rem =
 			min_t(unsigned int, ndwords - dw, max_dwords(obj));
@@ -1138,7 +1268,7 @@  static int igt_ctx_readonly(void *arg)
 		if (i915_gem_object_is_readonly(obj))
 			num_writes = 0;
 
-		err = cpu_check(obj, num_writes);
+		err = cpu_check(obj, idx++, num_writes);
 		if (err)
 			break;
 
@@ -1723,6 +1853,7 @@  int i915_gem_context_live_selftests(struct drm_i915_private *dev_priv)
 		SUBTEST(igt_ctx_exec),
 		SUBTEST(igt_ctx_readonly),
 		SUBTEST(igt_ctx_sseu),
+		SUBTEST(igt_shared_ctx_exec),
 		SUBTEST(igt_vm_isolation),
 	};
 
diff --git a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
index 3850ef4a5ec8..08a8f3d20854 100644
--- a/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/selftests/i915_gem_gtt.c
@@ -1020,7 +1020,6 @@  static int exercise_ppgtt(struct drm_i915_private *dev_priv,
 
 	err = func(dev_priv, &ppgtt->vm, 0, ppgtt->vm.total, end_time);
 
-	i915_ppgtt_close(&ppgtt->vm);
 	i915_ppgtt_put(ppgtt);
 out_unlock:
 	mutex_unlock(&dev_priv->drm.struct_mutex);
diff --git a/drivers/gpu/drm/i915/selftests/mock_context.c b/drivers/gpu/drm/i915/selftests/mock_context.c
index 1b5073a362eb..2189b606ca41 100644
--- a/drivers/gpu/drm/i915/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/selftests/mock_context.c
@@ -54,13 +54,17 @@  mock_context(struct drm_i915_private *i915,
 		goto err_handles;
 
 	if (name) {
+		struct i915_hw_ppgtt *ppgtt;
+
 		ctx->name = kstrdup(name, GFP_KERNEL);
 		if (!ctx->name)
 			goto err_put;
 
-		ctx->ppgtt = mock_ppgtt(i915, name);
-		if (!ctx->ppgtt)
+		ppgtt = mock_ppgtt(i915, name);
+		if (!ppgtt)
 			goto err_put;
+
+		__set_ppgtt(ctx, ppgtt);
 	}
 
 	return ctx;
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index be2fcdf3ba90..2cd79639d6b5 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -339,6 +339,8 @@  typedef struct _drm_i915_sarea {
 #define DRM_I915_PERF_ADD_CONFIG	0x37
 #define DRM_I915_PERF_REMOVE_CONFIG	0x38
 #define DRM_I915_QUERY			0x39
+#define DRM_I915_GEM_VM_CREATE		0x3a
+#define DRM_I915_GEM_VM_DESTROY		0x3b
 
 #define DRM_IOCTL_I915_INIT		DRM_IOW( DRM_COMMAND_BASE + DRM_I915_INIT, drm_i915_init_t)
 #define DRM_IOCTL_I915_FLUSH		DRM_IO ( DRM_COMMAND_BASE + DRM_I915_FLUSH)
@@ -397,6 +399,8 @@  typedef struct _drm_i915_sarea {
 #define DRM_IOCTL_I915_PERF_ADD_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_ADD_CONFIG, struct drm_i915_perf_oa_config)
 #define DRM_IOCTL_I915_PERF_REMOVE_CONFIG	DRM_IOW(DRM_COMMAND_BASE + DRM_I915_PERF_REMOVE_CONFIG, __u64)
 #define DRM_IOCTL_I915_QUERY			DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_QUERY, struct drm_i915_query)
+#define DRM_IOCTL_I915_GEM_VM_CREATE	DRM_IOWR(DRM_COMMAND_BASE + DRM_I915_GEM_VM_CREATE, struct drm_i915_gem_vm_control)
+#define DRM_IOCTL_I915_GEM_VM_DESTROY	DRM_IOW (DRM_COMMAND_BASE + DRM_I915_GEM_VM_DESTROY, struct drm_i915_gem_vm_control)
 
 /* Allow drivers to submit batchbuffers directly to hardware, relying
  * on the security mechanisms provided by hardware.
@@ -1444,6 +1448,26 @@  struct drm_i915_gem_context_destroy {
 	__u32 pad;
 };
 
+/*
+ * DRM_I915_GEM_VM_CREATE -
+ *
+ * Create a new virtual memory address space (ppGTT) for use within a context
+ * on the same file. Extensions can be provided to configure exactly how the
+ * address space is setup upon creation.
+ *
+ * The id of new VM (bound to the fd) for use with I915_CONTEXT_PARAM_VM is
+ * returned.
+ *
+ * DRM_I915_GEM_VM_DESTROY -
+ *
+ * Destroys a previously created VM id.
+ */
+struct drm_i915_gem_vm_control {
+	__u64 extensions;
+	__u32 flags;
+	__u32 id;
+};
+
 struct drm_i915_reg_read {
 	/*
 	 * Register offset.
@@ -1513,6 +1537,17 @@  struct drm_i915_gem_context_param {
 	 * drm_i915_gem_context_param_sseu.
 	 */
 #define I915_CONTEXT_PARAM_SSEU		0x7
+
+	/*
+	 * The id of the associated virtual memory address space (ppGTT) of
+	 * this context. Can be retrieved and passed to another context
+	 * (on the same fd) for both to use the same ppGTT and so share
+	 * address layouts, and avoid reloading the page tables on context
+	 * switches between themselves.
+	 *
+	 * See DRM_I915_GEM_VM_CREATE and DRM_I915_GEM_VM_DESTROY.
+	 */
+#define I915_CONTEXT_PARAM_VM		0x8
 	__u64 value;
 };