[PATCH v10 23/23] drm/i915/vm_bind: Support capture of persistent mappings
Niranjana Vishwanathapura
niranjana.vishwanathapura at intel.com
Wed Jan 18 18:19:16 UTC 2023
On Wed, Jan 18, 2023 at 12:45:08PM +0000, Matthew Auld wrote:
>On 18/01/2023 07:16, Niranjana Vishwanathapura wrote:
>>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 at intel.com>
>>Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura at 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);
>>+ }
>
>This stuff only exists on CONFIG_DRM_I915_CAPTURE_ERROR it seems?
>
Yah, will move it under CONFIG_DRM_I915_CAPTURE_ERROR.
>>+
>> 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;
>
>Same here, and a few other places.
>
We don't need CONFIG_DRM_I915_CAPTURE_ERROR check here as
this whole file is only compiled if this config is set.
>>+
>>+ /* 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);
>
>Now that stuff can be added to the capture_list outside of the exec,
>can't someone do an exec, followed by a bunch of vm_binds requesting
>capture for each one? With the idea of tricking the capture code into
>dumping the pages of non-cleared memory? (The GPU clear job has been
>created, but not actually completed yet).
>
>Say we have an IGT which creates a spinner or something on the vm,
>then creates a bunch of vm_binds, each asking for capture. What
>ensures that all the binds we are capturing here are valid when the
>spinner or whatever triggers a GPU hang i.e everything in capture_list
>has at least been cleared? With eb2 everything was tied to the rq, and
>if the rq has been submitted then all required async clears/moves must
>have already completed.
Ok, I think we can skip the capture here if i915_vma_verify_bind_complete()
returns false.
Thanks,
Niranjana
>
>>+ }
>>+ 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];
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