[PATCH v10 23/23] drm/i915/vm_bind: Support capture of persistent mappings

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

Support dump capture of persistent mappings upon user request.

Capture of a mapping is requested with the VM_BIND ioctl and
processed during the GPU error handling. They are synchronously
unbound during eviction so that no additional vma resource
reference taking is required in the submission path. Thus, a
list of persistent vmas requiring capture is maintained instead
of a list of vma resources.

v2: enable with CONFIG_DRM_I915_CAPTURE_ERROR, remove gfp
    overwrite, add kernel-doc and expand commit message
v3: Ensure vma->resource is valid during capture

Signed-off-by: Brian Welty <brian.welty@intel.com>
Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
---
 .../drm/i915/gem/i915_gem_vm_bind_object.c    | 13 +++++
 drivers/gpu/drm/i915/gt/intel_gtt.c           |  5 ++
 drivers/gpu/drm/i915/gt/intel_gtt.h           |  7 +++
 drivers/gpu/drm/i915/i915_gem.c               | 14 ++++-
 drivers/gpu/drm/i915/i915_gpu_error.c         | 52 ++++++++++++++++++-
 drivers/gpu/drm/i915/i915_vma.c               |  4 ++
 drivers/gpu/drm/i915/i915_vma_types.h         |  4 ++
 include/uapi/drm/i915_drm.h                   |  9 +++-
 8 files changed, 104 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
index 78e7c0642c5f..562a67a988f2 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_vm_bind_object.c
@@ -88,6 +88,12 @@ static void i915_gem_vm_bind_remove(struct i915_vma *vma, bool release_obj)
 {
 	lockdep_assert_held(&vma->vm->vm_bind_lock);
 
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+	mutex_lock(&vma->vm->vm_capture_lock);
+	if (!list_empty(&vma->vm_capture_link))
+		list_del_init(&vma->vm_capture_link);
+	mutex_unlock(&vma->vm->vm_capture_lock);
+#endif
 	spin_lock(&vma->vm->vm_rebind_lock);
 	if (!list_empty(&vma->vm_rebind_link))
 		list_del_init(&vma->vm_rebind_link);
@@ -357,6 +363,13 @@ static int i915_gem_vm_bind_obj(struct i915_address_space *vm,
 				continue;
 		}
 
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+		if (va->flags & I915_GEM_VM_BIND_CAPTURE) {
+			mutex_lock(&vm->vm_capture_lock);
+			list_add_tail(&vma->vm_capture_link, &vm->vm_capture_list);
+			mutex_unlock(&vm->vm_capture_lock);
+		}
+#endif
 		list_add_tail(&vma->vm_bind_link, &vm->vm_bound_list);
 		i915_vm_bind_it_insert(vma, &vm->va);
 		if (!obj->priv_root)
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c
index 2e4c9fabf3b8..103ca55222be 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.c
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.c
@@ -297,6 +297,11 @@ void i915_address_space_init(struct i915_address_space *vm, int subclass)
 	spin_lock_init(&vm->vm_rebind_lock);
 	spin_lock_init(&vm->userptr_invalidated_lock);
 	INIT_LIST_HEAD(&vm->userptr_invalidated_list);
+
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+	INIT_LIST_HEAD(&vm->vm_capture_list);
+	mutex_init(&vm->vm_capture_lock);
+#endif
 }
 
 void *__px_vaddr(struct drm_i915_gem_object *p)
diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.h b/drivers/gpu/drm/i915/gt/intel_gtt.h
index 620b4e020a9f..7f69e1d4fb5e 100644
--- a/drivers/gpu/drm/i915/gt/intel_gtt.h
+++ b/drivers/gpu/drm/i915/gt/intel_gtt.h
@@ -281,6 +281,13 @@ struct i915_address_space {
 	/** @root_obj: root object for dma-resv sharing by private objects */
 	struct drm_i915_gem_object *root_obj;
 
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+	/* @vm_capture_list: list of vm captures */
+	struct list_head vm_capture_list;
+	/* @vm_capture_lock: protects vm_capture_list */
+	struct mutex vm_capture_lock;
+#endif
+
 	/* Global GTT */
 	bool is_ggtt:1;
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 969581e7106f..d97822f203fc 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -143,6 +143,8 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 	while (!ret && (vma = list_first_entry_or_null(&obj->vma.list,
 						       struct i915_vma,
 						       obj_link))) {
+		bool sync_unbind = true;
+
 		list_move_tail(&vma->obj_link, &still_in_list);
 		if (!i915_vma_is_bound(vma, I915_VMA_BIND_MASK))
 			continue;
@@ -171,8 +173,18 @@ int i915_gem_object_unbind(struct drm_i915_gem_object *obj,
 		 * and destroy the vma from under us.
 		 */
 
+		/*
+		 * Synchronously unbind persistent mappings with capture
+		 * request so that vma->resource is valid in the error capture
+		 * path without needing extra reference taking in execbuf path.
+		 */
+		if (!mutex_lock_interruptible(&vma->vm->vm_capture_lock)) {
+			sync_unbind = !list_empty(&vma->vm_capture_link);
+			mutex_unlock(&vma->vm->vm_capture_lock);
+		}
+
 		ret = -EBUSY;
-		if (flags & I915_GEM_OBJECT_UNBIND_ASYNC) {
+		if (!sync_unbind && (flags & I915_GEM_OBJECT_UNBIND_ASYNC)) {
 			assert_object_held(vma->obj);
 			ret = i915_vma_unbind_async(vma, vm_trylock);
 		}
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 9d5d5a397b64..5ccd1eaea2a5 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1460,6 +1460,49 @@ capture_vma(struct intel_engine_capture_vma *next,
 	return next;
 }
 
+static struct intel_engine_capture_vma *
+capture_user_vm(struct intel_engine_capture_vma *capture,
+		struct i915_address_space *vm, gfp_t gfp)
+{
+	struct list_head vm_capture_list;
+	struct i915_vma *vma, *vn;
+	int err;
+
+	INIT_LIST_HEAD(&vm_capture_list);
+
+	err = mutex_lock_interruptible(&vm->vm_capture_lock);
+	if (err)
+		return capture;
+
+	/* vma->resource should be checked with vm->mutex held */
+	err = mutex_lock_interruptible(&vm->mutex);
+	if (err)
+		goto skip_user_vm_capture;
+
+	list_for_each_entry_safe(vma, vn, &vm->vm_capture_list,
+				 vm_capture_link) {
+		if (drm_WARN_ONCE(&vm->i915->drm, !vma->resource,
+				  "vma->resource expected!\n"))
+			continue;
+
+		i915_vma_resource_get(vma->resource);
+		list_move_tail(&vma->vm_capture_link, &vm_capture_list);
+	}
+	mutex_unlock(&vm->mutex);
+
+	list_for_each_entry(vma, &vm_capture_list, vm_capture_link) {
+		capture = capture_vma_snapshot(capture, vma->resource,
+					       gfp, "user");
+		i915_vma_resource_put(vma->resource);
+	}
+	list_splice_tail(&vm_capture_list, &vm->vm_capture_list);
+
+skip_user_vm_capture:
+	mutex_unlock(&vm->vm_capture_lock);
+
+	return capture;
+}
+
 static struct intel_engine_capture_vma *
 capture_user(struct intel_engine_capture_vma *capture,
 	     const struct i915_request *rq,
@@ -1467,6 +1510,8 @@ capture_user(struct intel_engine_capture_vma *capture,
 {
 	struct i915_capture_list *c;
 
+	capture = capture_user_vm(capture, rq->context->vm, gfp);
+
 	for (c = rq->capture_list; c; c = c->next)
 		capture = capture_vma_snapshot(capture, c->vma_res, gfp,
 					       "user");
@@ -1548,8 +1593,13 @@ intel_engine_coredump_add_request(struct intel_engine_coredump *ee,
 	 * as the simplest method to avoid being overwritten
 	 * by userspace.
 	 */
-	vma = capture_vma_snapshot(vma, rq->batch_res, gfp, "batch");
+
+	/*
+	 * Ensure capture_user_vm which takes vm->mutex gets called first
+	 * as snapshoting the first vma starts dma fence critical section.
+	 */
 	vma = capture_user(vma, rq, gfp);
+	vma = capture_vma_snapshot(vma, rq->batch_res, gfp, "batch");
 	vma = capture_vma(vma, rq->ring->vma, "ring", gfp);
 	vma = capture_vma(vma, rq->context->state, "HW context", gfp);
 
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 2f0994f0ed42..b47715fa773f 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -248,6 +248,10 @@ vma_create(struct drm_i915_gem_object *obj,
 	INIT_LIST_HEAD(&vma->non_priv_vm_bind_link);
 	INIT_LIST_HEAD(&vma->vm_rebind_link);
 	INIT_LIST_HEAD(&vma->userptr_invalidated_link);
+
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+	INIT_LIST_HEAD(&vma->vm_capture_link);
+#endif
 	return vma;
 
 err_unlock:
diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h
index 89f9854a6f69..c4fd61d51ce6 100644
--- a/drivers/gpu/drm/i915/i915_vma_types.h
+++ b/drivers/gpu/drm/i915/i915_vma_types.h
@@ -310,6 +310,10 @@ struct i915_vma {
 	struct list_head vm_rebind_link; /* Link in vm_rebind_list */
 	/** @userptr_invalidated_link: link to the vm->userptr_invalidated_list */
 	struct list_head userptr_invalidated_link;
+#if IS_ENABLED(CONFIG_DRM_I915_CAPTURE_ERROR)
+	/* @vm_capture_link: link to the captureable VMA list */
+	struct list_head vm_capture_link;
+#endif
 
 	/** Timeline fence for vm_bind completion notification */
 	struct {
diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index b9167f950327..5fde6020e339 100644
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -3925,12 +3925,17 @@ struct drm_i915_gem_vm_bind {
 	__u64 length;
 
 	/**
-	 * @flags: Currently reserved, MBZ.
+	 * @flags: Supported flags are:
+	 *
+	 * I915_GEM_VM_BIND_CAPTURE:
+	 * Capture this mapping in the dump upon GPU error.
+	 * CONFIG_DRM_I915_CAPTURE_ERROR should be enabled for valid capture.
 	 *
 	 * Note that @fence carries its own flags.
 	 */
 	__u64 flags;
-#define __I915_GEM_VM_BIND_UNKNOWN_FLAGS (~0ull)
+#define I915_GEM_VM_BIND_CAPTURE           (1ull << 0)
+#define __I915_GEM_VM_BIND_UNKNOWN_FLAGS   (-(I915_GEM_VM_BIND_CAPTURE << 1))
 
 	/** @rsvd: Reserved, MBZ */
 	__u64 rsvd[2];
-- 
2.21.0.rc0.32.g243a4c7e27