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Message-ID: <f00a4975cf32c3ae28124343a2c994acda083829.camel@linux.intel.com>
Date: Tue, 31 Oct 2023 11:32:45 +0100
From: Thomas Hellström
<thomas.hellstrom@...ux.intel.com>
To: Danilo Krummrich <dakr@...hat.com>, airlied@...il.com,
daniel@...ll.ch, matthew.brost@...el.com, sarah.walker@...tec.com,
donald.robson@...tec.com, boris.brezillon@...labora.com,
christian.koenig@....com, faith@...strand.net
Cc: dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH drm-misc-next v7 4/7] drm/gpuvm: add an abstraction for
a VM / BO combination
On Mon, 2023-10-23 at 22:16 +0200, Danilo Krummrich wrote:
> Add an abstraction layer between the drm_gpuva mappings of a
> particular
> drm_gem_object and this GEM object itself. The abstraction represents
> a
> combination of a drm_gem_object and drm_gpuvm. The drm_gem_object
> holds
> a list of drm_gpuvm_bo structures (the structure representing this
> abstraction), while each drm_gpuvm_bo contains list of mappings of
> this
> GEM object.
>
> This has multiple advantages:
>
> 1) We can use the drm_gpuvm_bo structure to attach it to various
> lists
> of the drm_gpuvm. This is useful for tracking external and evicted
> objects per VM, which is introduced in subsequent patches.
>
> 2) Finding mappings of a certain drm_gem_object mapped in a certain
> drm_gpuvm becomes much cheaper.
>
> 3) Drivers can derive and extend the structure to easily represent
> driver specific states of a BO for a certain GPUVM.
>
> The idea of this abstraction was taken from amdgpu, hence the credit
> for
> this idea goes to the developers of amdgpu.
>
> Cc: Christian König <christian.koenig@....com>
> Signed-off-by: Danilo Krummrich <dakr@...hat.com>
> ---
> drivers/gpu/drm/drm_gpuvm.c | 335 +++++++++++++++++++++--
> --
> drivers/gpu/drm/nouveau/nouveau_uvmm.c | 64 +++--
> include/drm/drm_gem.h | 32 +--
> include/drm/drm_gpuvm.h | 188 +++++++++++++-
> 4 files changed, 533 insertions(+), 86 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gpuvm.c
> b/drivers/gpu/drm/drm_gpuvm.c
> index c03332883432..7f4f5919f84c 100644
> --- a/drivers/gpu/drm/drm_gpuvm.c
> +++ b/drivers/gpu/drm/drm_gpuvm.c
> @@ -70,6 +70,18 @@
> * &drm_gem_object, such as the &drm_gem_object containing the root
> page table,
> * but it can also be a 'dummy' object, which can be allocated with
> * drm_gpuvm_resv_object_alloc().
> + *
> + * In order to connect a struct drm_gpuva its backing
> &drm_gem_object each
> + * &drm_gem_object maintains a list of &drm_gpuvm_bo structures, and
> each
> + * &drm_gpuvm_bo contains a list of &drm_gpuva structures.
> + *
> + * A &drm_gpuvm_bo is an abstraction that represents a combination
> of a
> + * &drm_gpuvm and a &drm_gem_object. Every such combination should
> be unique.
> + * This is ensured by the API through drm_gpuvm_bo_obtain() and
> + * drm_gpuvm_bo_obtain_prealloc() which first look into the
> corresponding
> + * &drm_gem_object list of &drm_gpuvm_bos for an existing instance
> of this
> + * particular combination. If not existent a new instance is created
> and linked
> + * to the &drm_gem_object.
> */
>
> /**
> @@ -395,21 +407,28 @@
> /**
> * DOC: Locking
> *
> - * Generally, the GPU VA manager does not take care of locking
> itself, it is
> - * the drivers responsibility to take care about locking. Drivers
> might want to
> - * protect the following operations: inserting, removing and
> iterating
> - * &drm_gpuva objects as well as generating all kinds of operations,
> such as
> - * split / merge or prefetch.
> - *
> - * The GPU VA manager also does not take care of the locking of the
> backing
> - * &drm_gem_object buffers GPU VA lists by itself; drivers are
> responsible to
> - * enforce mutual exclusion using either the GEMs dma_resv lock or
> alternatively
> - * a driver specific external lock. For the latter see also
> - * drm_gem_gpuva_set_lock().
> - *
> - * However, the GPU VA manager contains lockdep checks to ensure
> callers of its
> - * API hold the corresponding lock whenever the &drm_gem_objects GPU
> VA list is
> - * accessed by functions such as drm_gpuva_link() or
> drm_gpuva_unlink().
> + * In terms of managing &drm_gpuva entries DRM GPUVM does not take
> care of
> + * locking itself, it is the drivers responsibility to take care
> about locking.
> + * Drivers might want to protect the following operations:
> inserting, removing
> + * and iterating &drm_gpuva objects as well as generating all kinds
> of
> + * operations, such as split / merge or prefetch.
> + *
> + * DRM GPUVM also does not take care of the locking of the backing
> + * &drm_gem_object buffers GPU VA lists and &drm_gpuvm_bo
> abstractions by
> + * itself; drivers are responsible to enforce mutual exclusion using
> either the
> + * GEMs dma_resv lock or alternatively a driver specific external
> lock. For the
> + * latter see also drm_gem_gpuva_set_lock().
> + *
> + * However, DRM GPUVM contains lockdep checks to ensure callers of
> its API hold
> + * the corresponding lock whenever the &drm_gem_objects GPU VA list
> is accessed
> + * by functions such as drm_gpuva_link() or drm_gpuva_unlink(), but
> also
> + * drm_gpuvm_bo_obtain() and drm_gpuvm_bo_put().
> + *
> + * The latter is required since on creation and destruction of a
> &drm_gpuvm_bo
> + * the &drm_gpuvm_bo is attached / removed from the &drm_gem_objects
> gpuva list.
> + * Subsequent calls to drm_gpuvm_bo_obtain() for the same &drm_gpuvm
> and
> + * &drm_gem_object must be able to observe previous creations and
> destructions
> + * of &drm_gpuvm_bos in order to keep instances unique.
> */
>
> /**
> @@ -439,6 +458,7 @@
> * {
> * struct drm_gpuva_ops *ops;
> * struct drm_gpuva_op *op
> + * struct drm_gpuvm_bo *vm_bo;
> *
> * driver_lock_va_space();
> * ops = drm_gpuvm_sm_map_ops_create(gpuvm, addr, range,
> @@ -446,6 +466,10 @@
> * if (IS_ERR(ops))
> * return PTR_ERR(ops);
> *
> + * vm_bo = drm_gpuvm_bo_obtain(gpuvm, obj);
> + * if (IS_ERR(vm_bo))
> + * return PTR_ERR(vm_bo);
> + *
> * drm_gpuva_for_each_op(op, ops) {
> * struct drm_gpuva *va;
> *
> @@ -458,7 +482,7 @@
> *
> * driver_vm_map();
> * drm_gpuva_map(gpuvm, va, &op->map);
> - * drm_gpuva_link(va);
> + * drm_gpuva_link(va, vm_bo);
> *
> * break;
> * case DRM_GPUVA_OP_REMAP: {
> @@ -485,11 +509,11 @@
> * driver_vm_remap();
> * drm_gpuva_remap(prev, next, &op-
> >remap);
> *
> - * drm_gpuva_unlink(va);
> * if (prev)
> - * drm_gpuva_link(prev);
> + * drm_gpuva_link(prev, va-
> >vm_bo);
> * if (next)
> - * drm_gpuva_link(next);
> + * drm_gpuva_link(next, va-
> >vm_bo);
> + * drm_gpuva_unlink(va);
> *
> * break;
> * }
> @@ -505,6 +529,7 @@
> * break;
> * }
> * }
> + * drm_gpuvm_bo_put(vm_bo);
> * driver_unlock_va_space();
> *
> * return 0;
> @@ -514,6 +539,7 @@
> *
> * struct driver_context {
> * struct drm_gpuvm *gpuvm;
> + * struct drm_gpuvm_bo *vm_bo;
> * struct drm_gpuva *new_va;
> * struct drm_gpuva *prev_va;
> * struct drm_gpuva *next_va;
> @@ -534,6 +560,7 @@
> * struct drm_gem_object *obj, u64
> offset)
> * {
> * struct driver_context ctx;
> + * struct drm_gpuvm_bo *vm_bo;
> * struct drm_gpuva_ops *ops;
> * struct drm_gpuva_op *op;
> * int ret = 0;
> @@ -543,16 +570,23 @@
> * ctx.new_va = kzalloc(sizeof(*ctx.new_va),
> GFP_KERNEL);
> * ctx.prev_va = kzalloc(sizeof(*ctx.prev_va),
> GFP_KERNEL);
> * ctx.next_va = kzalloc(sizeof(*ctx.next_va),
> GFP_KERNEL);
> - * if (!ctx.new_va || !ctx.prev_va || !ctx.next_va) {
> + * ctx.vm_bo = drm_gpuvm_bo_create(gpuvm, obj);
> + * if (!ctx.new_va || !ctx.prev_va || !ctx.next_va ||
> !vm_bo) {
> * ret = -ENOMEM;
> * goto out;
> * }
> *
> + * // Typically protected with a driver specific GEM
> gpuva lock
> + * // used in the fence signaling path for
> drm_gpuva_link() and
> + * // drm_gpuva_unlink(), hence pre-allocate.
> + * ctx.vm_bo = drm_gpuvm_bo_obtain_prealloc(ctx.vm_bo);
> + *
> * driver_lock_va_space();
> * ret = drm_gpuvm_sm_map(gpuvm, &ctx, addr, range, obj,
> offset);
> * driver_unlock_va_space();
> *
> * out:
> + * drm_gpuvm_bo_put(ctx.vm_bo);
> * kfree(ctx.new_va);
> * kfree(ctx.prev_va);
> * kfree(ctx.next_va);
> @@ -565,7 +599,7 @@
> *
> * drm_gpuva_map(ctx->vm, ctx->new_va, &op->map);
> *
> - * drm_gpuva_link(ctx->new_va);
> + * drm_gpuva_link(ctx->new_va, ctx->vm_bo);
> *
> * // prevent the new GPUVA from being freed in
> * // driver_mapping_create()
> @@ -577,22 +611,23 @@
> * int driver_gpuva_remap(struct drm_gpuva_op *op, void *__ctx)
> * {
> * struct driver_context *ctx = __ctx;
> + * struct drm_gpuva *va = op->remap.unmap->va;
> *
> * drm_gpuva_remap(ctx->prev_va, ctx->next_va, &op-
> >remap);
> *
> - * drm_gpuva_unlink(op->remap.unmap->va);
> - * kfree(op->remap.unmap->va);
> - *
> * if (op->remap.prev) {
> - * drm_gpuva_link(ctx->prev_va);
> + * drm_gpuva_link(ctx->prev_va, va->vm_bo);
> * ctx->prev_va = NULL;
> * }
> *
> * if (op->remap.next) {
> - * drm_gpuva_link(ctx->next_va);
> + * drm_gpuva_link(ctx->next_va, va->vm_bo);
> * ctx->next_va = NULL;
> * }
> *
> + * drm_gpuva_unlink(va);
> + * kfree(va);
> + *
> * return 0;
> * }
> *
> @@ -774,6 +809,194 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
> }
> EXPORT_SYMBOL_GPL(drm_gpuvm_destroy);
>
> +/**
> + * drm_gpuvm_bo_create() - create a new instance of struct
> drm_gpuvm_bo
> + * @gpuvm: The &drm_gpuvm the @obj is mapped in.
> + * @obj: The &drm_gem_object being mapped in the @gpuvm.
> + *
> + * If provided by the driver, this function uses the &drm_gpuvm_ops
> + * vm_bo_alloc() callback to allocate.
> + *
> + * Returns: a pointer to the &drm_gpuvm_bo on success, NULL on
Still needs s/Returns:/Return:/g
> failure
> + */
> +struct drm_gpuvm_bo *
> +drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj)
> +{
> + const struct drm_gpuvm_ops *ops = gpuvm->ops;
> + struct drm_gpuvm_bo *vm_bo;
> +
> + if (ops && ops->vm_bo_alloc)
> + vm_bo = ops->vm_bo_alloc();
> + else
> + vm_bo = kzalloc(sizeof(*vm_bo), GFP_KERNEL);
> +
> + if (unlikely(!vm_bo))
> + return NULL;
> +
> + vm_bo->vm = gpuvm;
> + vm_bo->obj = obj;
> + drm_gem_object_get(obj);
> +
> + kref_init(&vm_bo->kref);
> + INIT_LIST_HEAD(&vm_bo->list.gpuva);
> + INIT_LIST_HEAD(&vm_bo->list.entry.gem);
> +
> + return vm_bo;
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_create);
> +
> +static void
> +drm_gpuvm_bo_destroy(struct kref *kref)
> +{
> + struct drm_gpuvm_bo *vm_bo = container_of(kref, struct
> drm_gpuvm_bo,
> + kref);
> + struct drm_gpuvm *gpuvm = vm_bo->vm;
> + const struct drm_gpuvm_ops *ops = gpuvm->ops;
> + struct drm_gem_object *obj = vm_bo->obj;
> + bool lock = !drm_gpuvm_resv_protected(gpuvm);
> +
> + if (!lock)
> + drm_gpuvm_resv_assert_held(gpuvm);
> +
> + drm_gem_gpuva_assert_lock_held(obj);
> + list_del(&vm_bo->list.entry.gem);
> +
> + if (ops && ops->vm_bo_free)
> + ops->vm_bo_free(vm_bo);
> + else
> + kfree(vm_bo);
> +
> + drm_gem_object_put(obj);
> +}
> +
> +/**
> + * drm_gpuvm_bo_put() - drop a struct drm_gpuvm_bo reference
> + * @vm_bo: the &drm_gpuvm_bo to release the reference of
> + *
> + * This releases a reference to @vm_bo.
> + *
> + * If the reference count drops to zero, the &gpuvm_bo is destroyed,
> which
> + * includes removing it from the GEMs gpuva list. Hence, if a call
> to this
> + * function can potentially let the reference count to zero the
> caller must
> + * hold the dma-resv or driver specific GEM gpuva lock.
> + */
> +void
> +drm_gpuvm_bo_put(struct drm_gpuvm_bo *vm_bo)
> +{
> + if (vm_bo)
> + kref_put(&vm_bo->kref, drm_gpuvm_bo_destroy);
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_put);
> +
> +static struct drm_gpuvm_bo *
> +__drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj)
> +{
> + struct drm_gpuvm_bo *vm_bo;
> +
> + drm_gem_gpuva_assert_lock_held(obj);
> + drm_gem_for_each_gpuvm_bo(vm_bo, obj)
> + if (vm_bo->vm == gpuvm)
> + return vm_bo;
> +
> + return NULL;
> +}
> +
> +/**
> + * drm_gpuvm_bo_find() - find the &drm_gpuvm_bo for the given
> + * &drm_gpuvm and &drm_gem_object
> + * @gpuvm: The &drm_gpuvm the @obj is mapped in.
> + * @obj: The &drm_gem_object being mapped in the @gpuvm.
> + *
> + * Find the &drm_gpuvm_bo representing the combination of the given
> + * &drm_gpuvm and &drm_gem_object. If found, increases the reference
> + * count of the &drm_gpuvm_bo accordingly.
> + *
> + * Returns: a pointer to the &drm_gpuvm_bo on success, NULL on
> failure
> + */
> +struct drm_gpuvm_bo *
> +drm_gpuvm_bo_find(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj)
> +{
> + struct drm_gpuvm_bo *vm_bo = __drm_gpuvm_bo_find(gpuvm, obj);
> +
> + return vm_bo ? drm_gpuvm_bo_get(vm_bo) : NULL;
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_find);
> +
> +/**
> + * drm_gpuvm_bo_obtain() - obtains and instance of the &drm_gpuvm_bo
> for the
> + * given &drm_gpuvm and &drm_gem_object
> + * @gpuvm: The &drm_gpuvm the @obj is mapped in.
> + * @obj: The &drm_gem_object being mapped in the @gpuvm.
> + *
> + * Find the &drm_gpuvm_bo representing the combination of the given
> + * &drm_gpuvm and &drm_gem_object. If found, increases the reference
> + * count of the &drm_gpuvm_bo accordingly. If not found, allocates a
> new
> + * &drm_gpuvm_bo.
> + *
> + * A new &drm_gpuvm_bo is added to the GEMs gpuva list.
> + *
> + * Returns: a pointer to the &drm_gpuvm_bo on success, an ERR_PTR on
> failure
> + */
> +struct drm_gpuvm_bo *
> +drm_gpuvm_bo_obtain(struct drm_gpuvm *gpuvm,
> + struct drm_gem_object *obj)
> +{
> + struct drm_gpuvm_bo *vm_bo;
> +
> + vm_bo = drm_gpuvm_bo_find(gpuvm, obj);
> + if (vm_bo)
> + return vm_bo;
> +
> + vm_bo = drm_gpuvm_bo_create(gpuvm, obj);
> + if (!vm_bo)
> + return ERR_PTR(-ENOMEM);
> +
> + drm_gem_gpuva_assert_lock_held(obj);
> + list_add_tail(&vm_bo->list.entry.gem, &obj->gpuva.list);
> +
> + return vm_bo;
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain);
> +
> +/**
> + * drm_gpuvm_bo_obtain_prealloc() - obtains and instance of the
> &drm_gpuvm_bo
> + * for the given &drm_gpuvm and &drm_gem_object
> + * @__vm_bo: A pre-allocated struct drm_gpuvm_bo.
> + *
> + * Find the &drm_gpuvm_bo representing the combination of the given
> + * &drm_gpuvm and &drm_gem_object. If found, increases the reference
> + * count of the found &drm_gpuvm_bo accordingly, while the @__vm_bo
> reference
> + * count is decreased. If not found @__vm_bo is returned without
> further
> + * increase of the reference count.
> + *
> + * A new &drm_gpuvm_bo is added to the GEMs gpuva list.
> + *
> + * Returns: a pointer to the found &drm_gpuvm_bo or @__vm_bo if no
> existing
> + * &drm_gpuvm_bo was found
> + */
> +struct drm_gpuvm_bo *
> +drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm_bo *__vm_bo)
> +{
> + struct drm_gpuvm *gpuvm = __vm_bo->vm;
> + struct drm_gem_object *obj = __vm_bo->obj;
> + struct drm_gpuvm_bo *vm_bo;
> +
> + vm_bo = drm_gpuvm_bo_find(gpuvm, obj);
> + if (vm_bo) {
> + drm_gpuvm_bo_put(__vm_bo);
> + return vm_bo;
> + }
> +
> + drm_gem_gpuva_assert_lock_held(obj);
> + list_add_tail(&__vm_bo->list.entry.gem, &obj->gpuva.list);
> +
> + return __vm_bo;
> +}
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_prealloc);
> +
> static int
> __drm_gpuva_insert(struct drm_gpuvm *gpuvm,
> struct drm_gpuva *va)
> @@ -864,24 +1087,33 @@ EXPORT_SYMBOL_GPL(drm_gpuva_remove);
> /**
> * drm_gpuva_link() - link a &drm_gpuva
> * @va: the &drm_gpuva to link
> + * @vm_bo: the &drm_gpuvm_bo to add the &drm_gpuva to
> *
> - * This adds the given &va to the GPU VA list of the &drm_gem_object
> it is
> - * associated with.
> + * This adds the given &va to the GPU VA list of the &drm_gpuvm_bo
> and the
> + * &drm_gpuvm_bo to the &drm_gem_object it is associated with.
> + *
> + * For every &drm_gpuva entry added to the &drm_gpuvm_bo an
> additional
> + * reference of the latter is taken.
> *
> * This function expects the caller to protect the GEM's GPUVA list
> against
> - * concurrent access using the GEMs dma_resv lock.
> + * concurrent access using either the GEMs dma_resv lock or a driver
> specific
> + * lock set through drm_gem_gpuva_set_lock().
> */
> void
> -drm_gpuva_link(struct drm_gpuva *va)
> +drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo *vm_bo)
> {
> struct drm_gem_object *obj = va->gem.obj;
> + struct drm_gpuvm *gpuvm = va->vm;
>
> if (unlikely(!obj))
> return;
>
> - drm_gem_gpuva_assert_lock_held(obj);
> + drm_WARN_ON(gpuvm->drm, obj != vm_bo->obj);
>
> - list_add_tail(&va->gem.entry, &obj->gpuva.list);
> + va->vm_bo = drm_gpuvm_bo_get(vm_bo);
> +
> + drm_gem_gpuva_assert_lock_held(obj);
> + list_add_tail(&va->gem.entry, &vm_bo->list.gpuva);
> }
> EXPORT_SYMBOL_GPL(drm_gpuva_link);
>
> @@ -892,20 +1124,31 @@ EXPORT_SYMBOL_GPL(drm_gpuva_link);
> * This removes the given &va from the GPU VA list of the
> &drm_gem_object it is
> * associated with.
> *
> + * This removes the given &va from the GPU VA list of the
> &drm_gpuvm_bo and
> + * the &drm_gpuvm_bo from the &drm_gem_object it is associated with
> in case
> + * this call unlinks the last &drm_gpuva from the &drm_gpuvm_bo.
> + *
> + * For every &drm_gpuva entry removed from the &drm_gpuvm_bo a
> reference of
> + * the latter is dropped.
> + *
> * This function expects the caller to protect the GEM's GPUVA list
> against
> - * concurrent access using the GEMs dma_resv lock.
> + * concurrent access using either the GEMs dma_resv lock or a driver
> specific
> + * lock set through drm_gem_gpuva_set_lock().
> */
> void
> drm_gpuva_unlink(struct drm_gpuva *va)
> {
> struct drm_gem_object *obj = va->gem.obj;
> + struct drm_gpuvm_bo *vm_bo = va->vm_bo;
>
> if (unlikely(!obj))
> return;
>
> drm_gem_gpuva_assert_lock_held(obj);
> -
> list_del_init(&va->gem.entry);
> +
> + va->vm_bo = NULL;
> + drm_gpuvm_bo_put(vm_bo);
> }
> EXPORT_SYMBOL_GPL(drm_gpuva_unlink);
>
> @@ -1050,10 +1293,10 @@ drm_gpuva_remap(struct drm_gpuva *prev,
> struct drm_gpuva *next,
> struct drm_gpuva_op_remap *op)
> {
> - struct drm_gpuva *curr = op->unmap->va;
> - struct drm_gpuvm *gpuvm = curr->vm;
> + struct drm_gpuva *va = op->unmap->va;
> + struct drm_gpuvm *gpuvm = va->vm;
>
> - drm_gpuva_remove(curr);
> + drm_gpuva_remove(va);
>
> if (op->prev) {
> drm_gpuva_init_from_op(prev, op->prev);
> @@ -1695,9 +1938,8 @@ drm_gpuvm_prefetch_ops_create(struct drm_gpuvm
> *gpuvm,
> EXPORT_SYMBOL_GPL(drm_gpuvm_prefetch_ops_create);
>
> /**
> - * drm_gpuvm_gem_unmap_ops_create() - creates the &drm_gpuva_ops to
> unmap a GEM
> - * @gpuvm: the &drm_gpuvm representing the GPU VA space
> - * @obj: the &drm_gem_object to unmap
> + * drm_gpuvm_bo_unmap_ops_create() - creates the &drm_gpuva_ops to
> unmap a GEM
> + * @vm_bo: the &drm_gpuvm_bo abstraction
> *
> * This function creates a list of operations to perform unmapping
> for every
> * GPUVA attached to a GEM.
> @@ -1714,15 +1956,14 @@
> EXPORT_SYMBOL_GPL(drm_gpuvm_prefetch_ops_create);
> * Returns: a pointer to the &drm_gpuva_ops on success, an ERR_PTR
> on failure
> */
> struct drm_gpuva_ops *
> -drm_gpuvm_gem_unmap_ops_create(struct drm_gpuvm *gpuvm,
> - struct drm_gem_object *obj)
> +drm_gpuvm_bo_unmap_ops_create(struct drm_gpuvm_bo *vm_bo)
> {
> struct drm_gpuva_ops *ops;
> struct drm_gpuva_op *op;
> struct drm_gpuva *va;
> int ret;
>
> - drm_gem_gpuva_assert_lock_held(obj);
> + drm_gem_gpuva_assert_lock_held(vm_bo->obj);
>
> ops = kzalloc(sizeof(*ops), GFP_KERNEL);
> if (!ops)
> @@ -1730,8 +1971,8 @@ drm_gpuvm_gem_unmap_ops_create(struct drm_gpuvm
> *gpuvm,
>
> INIT_LIST_HEAD(&ops->list);
>
> - drm_gem_for_each_gpuva(va, obj) {
> - op = gpuva_op_alloc(gpuvm);
> + drm_gpuvm_bo_for_each_va(va, vm_bo) {
> + op = gpuva_op_alloc(vm_bo->vm);
> if (!op) {
> ret = -ENOMEM;
> goto err_free_ops;
> @@ -1745,10 +1986,10 @@ drm_gpuvm_gem_unmap_ops_create(struct
> drm_gpuvm *gpuvm,
> return ops;
>
> err_free_ops:
> - drm_gpuva_ops_free(gpuvm, ops);
> + drm_gpuva_ops_free(vm_bo->vm, ops);
> return ERR_PTR(ret);
> }
> -EXPORT_SYMBOL_GPL(drm_gpuvm_gem_unmap_ops_create);
> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_unmap_ops_create);
>
> /**
> * drm_gpuva_ops_free() - free the given &drm_gpuva_ops
> diff --git a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> index ed439bf4032f..1e95b0a1b047 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_uvmm.c
> @@ -62,6 +62,8 @@ struct bind_job_op {
> enum vm_bind_op op;
> u32 flags;
>
> + struct drm_gpuvm_bo *vm_bo;
> +
> struct {
> u64 addr;
> u64 range;
> @@ -1113,22 +1115,28 @@ bind_validate_region(struct nouveau_job *job)
> }
>
> static void
> -bind_link_gpuvas(struct drm_gpuva_ops *ops, struct
> nouveau_uvma_prealloc *new)
> +bind_link_gpuvas(struct bind_job_op *bop)
> {
> + struct nouveau_uvma_prealloc *new = &bop->new;
> + struct drm_gpuvm_bo *vm_bo = bop->vm_bo;
> + struct drm_gpuva_ops *ops = bop->ops;
> struct drm_gpuva_op *op;
>
> drm_gpuva_for_each_op(op, ops) {
> switch (op->op) {
> case DRM_GPUVA_OP_MAP:
> - drm_gpuva_link(&new->map->va);
> + drm_gpuva_link(&new->map->va, vm_bo);
> break;
> - case DRM_GPUVA_OP_REMAP:
> + case DRM_GPUVA_OP_REMAP: {
> + struct drm_gpuva *va = op->remap.unmap->va;
> +
> if (op->remap.prev)
> - drm_gpuva_link(&new->prev->va);
> + drm_gpuva_link(&new->prev->va, va-
> >vm_bo);
> if (op->remap.next)
> - drm_gpuva_link(&new->next->va);
> - drm_gpuva_unlink(op->remap.unmap->va);
> + drm_gpuva_link(&new->next->va, va-
> >vm_bo);
> + drm_gpuva_unlink(va);
> break;
> + }
> case DRM_GPUVA_OP_UNMAP:
> drm_gpuva_unlink(op->unmap.va);
> break;
> @@ -1150,10 +1158,18 @@ nouveau_uvmm_bind_job_submit(struct
> nouveau_job *job)
>
> list_for_each_op(op, &bind_job->ops) {
> if (op->op == OP_MAP) {
> - op->gem.obj = drm_gem_object_lookup(job-
> >file_priv,
> - op-
> >gem.handle);
> - if (!op->gem.obj)
> + struct drm_gem_object *obj;
> +
> + obj = drm_gem_object_lookup(job->file_priv,
> + op->gem.handle);
> + if (!(op->gem.obj = obj))
> return -ENOENT;
> +
> + dma_resv_lock(obj->resv, NULL);
> + op->vm_bo = drm_gpuvm_bo_obtain(&uvmm->base,
> obj);
> + dma_resv_unlock(obj->resv);
> + if (IS_ERR(op->vm_bo))
> + return PTR_ERR(op->vm_bo);
> }
>
> ret = bind_validate_op(job, op);
> @@ -1364,7 +1380,7 @@ nouveau_uvmm_bind_job_submit(struct nouveau_job
> *job)
> case OP_UNMAP_SPARSE:
> case OP_MAP:
> case OP_UNMAP:
> - bind_link_gpuvas(op->ops, &op->new);
> + bind_link_gpuvas(op);
> break;
> default:
> break;
> @@ -1511,6 +1527,12 @@ nouveau_uvmm_bind_job_free_work_fn(struct
> work_struct *work)
> if (!IS_ERR_OR_NULL(op->ops))
> drm_gpuva_ops_free(&uvmm->base, op->ops);
>
> + if (!IS_ERR_OR_NULL(op->vm_bo)) {
> + dma_resv_lock(obj->resv, NULL);
> + drm_gpuvm_bo_put(op->vm_bo);
> + dma_resv_unlock(obj->resv);
> + }
> +
> if (obj)
> drm_gem_object_put(obj);
> }
> @@ -1776,15 +1798,18 @@ void
> nouveau_uvmm_bo_map_all(struct nouveau_bo *nvbo, struct nouveau_mem
> *mem)
> {
> struct drm_gem_object *obj = &nvbo->bo.base;
> + struct drm_gpuvm_bo *vm_bo;
> struct drm_gpuva *va;
>
> dma_resv_assert_held(obj->resv);
>
> - drm_gem_for_each_gpuva(va, obj) {
> - struct nouveau_uvma *uvma = uvma_from_va(va);
> + drm_gem_for_each_gpuvm_bo(vm_bo, obj) {
> + drm_gpuvm_bo_for_each_va(va, vm_bo) {
> + struct nouveau_uvma *uvma = uvma_from_va(va);
>
> - nouveau_uvma_map(uvma, mem);
> - drm_gpuva_invalidate(va, false);
> + nouveau_uvma_map(uvma, mem);
> + drm_gpuva_invalidate(va, false);
> + }
> }
> }
>
> @@ -1792,15 +1817,18 @@ void
> nouveau_uvmm_bo_unmap_all(struct nouveau_bo *nvbo)
> {
> struct drm_gem_object *obj = &nvbo->bo.base;
> + struct drm_gpuvm_bo *vm_bo;
> struct drm_gpuva *va;
>
> dma_resv_assert_held(obj->resv);
>
> - drm_gem_for_each_gpuva(va, obj) {
> - struct nouveau_uvma *uvma = uvma_from_va(va);
> + drm_gem_for_each_gpuvm_bo(vm_bo, obj) {
> + drm_gpuvm_bo_for_each_va(va, vm_bo) {
> + struct nouveau_uvma *uvma = uvma_from_va(va);
>
> - nouveau_uvma_unmap(uvma);
> - drm_gpuva_invalidate(va, true);
> + nouveau_uvma_unmap(uvma);
> + drm_gpuva_invalidate(va, true);
> + }
> }
> }
>
> diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
> index 16364487fde9..369505447acd 100644
> --- a/include/drm/drm_gem.h
> +++ b/include/drm/drm_gem.h
> @@ -580,7 +580,7 @@ int drm_gem_evict(struct drm_gem_object *obj);
> * drm_gem_gpuva_init() - initialize the gpuva list of a GEM object
> * @obj: the &drm_gem_object
> *
> - * This initializes the &drm_gem_object's &drm_gpuva list.
> + * This initializes the &drm_gem_object's &drm_gpuvm_bo list.
> *
> * Calling this function is only necessary for drivers intending to
> support the
> * &drm_driver_feature DRIVER_GEM_GPUVA.
> @@ -593,28 +593,28 @@ static inline void drm_gem_gpuva_init(struct
> drm_gem_object *obj)
> }
>
> /**
> - * drm_gem_for_each_gpuva() - iternator to walk over a list of
> gpuvas
> - * @entry__: &drm_gpuva structure to assign to in each iteration
> step
> - * @obj__: the &drm_gem_object the &drm_gpuvas to walk are
> associated with
> + * drm_gem_for_each_gpuvm_bo() - iterator to walk over a list of
> &drm_gpuvm_bo
> + * @entry__: &drm_gpuvm_bo structure to assign to in each iteration
> step
> + * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are
> associated with
> *
> - * This iterator walks over all &drm_gpuva structures associated
> with the
> - * &drm_gpuva_manager.
> + * This iterator walks over all &drm_gpuvm_bo structures associated
> with the
> + * &drm_gem_object.
> */
> -#define drm_gem_for_each_gpuva(entry__, obj__) \
> - list_for_each_entry(entry__, &(obj__)->gpuva.list, gem.entry)
> +#define drm_gem_for_each_gpuvm_bo(entry__, obj__) \
> + list_for_each_entry(entry__, &(obj__)->gpuva.list,
> list.entry.gem)
>
> /**
> - * drm_gem_for_each_gpuva_safe() - iternator to safely walk over a
> list of
> - * gpuvas
> - * @entry__: &drm_gpuva structure to assign to in each iteration
> step
> - * @next__: &next &drm_gpuva to store the next step
> - * @obj__: the &drm_gem_object the &drm_gpuvas to walk are
> associated with
> + * drm_gem_for_each_gpuvm_bo_safe() - iterator to safely walk over a
> list of
> + * &drm_gpuvm_bo
> + * @entry__: &drm_gpuvm_bostructure to assign to in each iteration
> step
> + * @next__: &next &drm_gpuvm_bo to store the next step
> + * @obj__: the &drm_gem_object the &drm_gpuvm_bo to walk are
> associated with
> *
> - * This iterator walks over all &drm_gpuva structures associated
> with the
> + * This iterator walks over all &drm_gpuvm_bo structures associated
> with the
> * &drm_gem_object. It is implemented with
> list_for_each_entry_safe(), hence
> * it is save against removal of elements.
> */
> -#define drm_gem_for_each_gpuva_safe(entry__, next__, obj__) \
> - list_for_each_entry_safe(entry__, next__, &(obj__)-
> >gpuva.list, gem.entry)
> +#define drm_gem_for_each_gpuvm_bo_safe(entry__, next__, obj__) \
> + list_for_each_entry_safe(entry__, next__, &(obj__)-
> >gpuva.list, list.entry.gem)
>
> #endif /* __DRM_GEM_H__ */
> diff --git a/include/drm/drm_gpuvm.h b/include/drm/drm_gpuvm.h
> index 47cbacb244b9..466fdd76c71a 100644
> --- a/include/drm/drm_gpuvm.h
> +++ b/include/drm/drm_gpuvm.h
> @@ -25,6 +25,7 @@
> * OTHER DEALINGS IN THE SOFTWARE.
> */
>
> +#include <linux/dma-resv.h>
> #include <linux/list.h>
> #include <linux/rbtree.h>
> #include <linux/types.h>
> @@ -33,6 +34,7 @@
> #include <drm/drm_gem.h>
>
> struct drm_gpuvm;
> +struct drm_gpuvm_bo;
> struct drm_gpuvm_ops;
>
> /**
> @@ -73,6 +75,12 @@ struct drm_gpuva {
> */
> struct drm_gpuvm *vm;
>
> + /**
> + * @vm_bo: the &drm_gpuvm_bo abstraction for the mapped
> + * &drm_gem_object
> + */
> + struct drm_gpuvm_bo *vm_bo;
> +
> /**
> * @flags: the &drm_gpuva_flags for this mapping
> */
> @@ -108,7 +116,7 @@ struct drm_gpuva {
> struct drm_gem_object *obj;
>
> /**
> - * @entry: the &list_head to attach this object to a
> &drm_gem_object
> + * @entry: the &list_head to attach this object to a
> &drm_gpuvm_bo
> */
> struct list_head entry;
> } gem;
> @@ -141,7 +149,7 @@ struct drm_gpuva {
> int drm_gpuva_insert(struct drm_gpuvm *gpuvm, struct drm_gpuva *va);
> void drm_gpuva_remove(struct drm_gpuva *va);
>
> -void drm_gpuva_link(struct drm_gpuva *va);
> +void drm_gpuva_link(struct drm_gpuva *va, struct drm_gpuvm_bo
> *vm_bo);
> void drm_gpuva_unlink(struct drm_gpuva *va);
>
> struct drm_gpuva *drm_gpuva_find(struct drm_gpuvm *gpuvm,
> @@ -188,10 +196,16 @@ static inline bool drm_gpuva_invalidated(struct
> drm_gpuva *va)
> * enum drm_gpuvm_flags - flags for struct drm_gpuvm
> */
> enum drm_gpuvm_flags {
> + /**
> + * @DRM_GPUVM_RESV_PROTECTED: GPUVM is protected externally
> by the
> + * GPUVM's &dma_resv lock
> + */
> + DRM_GPUVM_RESV_PROTECTED = BIT(0),
> +
> /**
> * @DRM_GPUVM_USERBITS: user defined bits
> */
> - DRM_GPUVM_USERBITS = BIT(0),
> + DRM_GPUVM_USERBITS = BIT(1),
> };
>
> /**
> @@ -280,6 +294,19 @@ bool drm_gpuvm_interval_empty(struct drm_gpuvm
> *gpuvm, u64 addr, u64 range);
> struct drm_gem_object *
> drm_gpuvm_resv_object_alloc(struct drm_device *drm);
>
> +/**
> + * drm_gpuvm_resv_protected() - indicates whether
> &DRM_GPUVM_RESV_PROTECTED is
> + * set
> + * @gpuvm: the &drm_gpuvm
> + *
> + * Returns: true if &DRM_GPUVM_RESV_PROTECTED is set, false
> otherwise.
> + */
> +static inline bool
> +drm_gpuvm_resv_protected(struct drm_gpuvm *gpuvm)
> +{
> + return gpuvm->flags & DRM_GPUVM_RESV_PROTECTED;
> +}
> +
> /**
> * drm_gpuvm_resv() - returns the &drm_gpuvm's &dma_resv
> * @gpuvm__: the &drm_gpuvm
> @@ -298,6 +325,12 @@ drm_gpuvm_resv_object_alloc(struct drm_device
> *drm);
> */
> #define drm_gpuvm_resv_obj(gpuvm__) ((gpuvm__)->r_obj)
>
> +#define drm_gpuvm_resv_held(gpuvm__) \
> + dma_resv_held(drm_gpuvm_resv(gpuvm__))
> +
> +#define drm_gpuvm_resv_assert_held(gpuvm__) \
> + dma_resv_assert_held(drm_gpuvm_resv(gpuvm__))
> +
> #define drm_gpuvm_resv_held(gpuvm__) \
> dma_resv_held(drm_gpuvm_resv(gpuvm__))
>
> @@ -382,6 +415,128 @@ __drm_gpuva_next(struct drm_gpuva *va)
> #define drm_gpuvm_for_each_va_safe(va__, next__, gpuvm__) \
> list_for_each_entry_safe(va__, next__, &(gpuvm__)->rb.list,
> rb.entry)
>
> +/**
> + * struct drm_gpuvm_bo - structure representing a &drm_gpuvm and
> + * &drm_gem_object combination
> + *
> + * This structure is an abstraction representing a &drm_gpuvm and
> + * &drm_gem_object combination. It serves as an indirection to
> accelerate
> + * iterating all &drm_gpuvas within a &drm_gpuvm backed by the same
> + * &drm_gem_object.
> + *
> + * Furthermore it is used cache evicted GEM objects for a certain
> GPU-VM to
> + * accelerate validation.
> + *
> + * Typically, drivers want to create an instance of a struct
> drm_gpuvm_bo once
> + * a GEM object is mapped first in a GPU-VM and release the instance
> once the
> + * last mapping of the GEM object in this GPU-VM is unmapped.
> + */
> +struct drm_gpuvm_bo {
> + /**
> + * @vm: The &drm_gpuvm the @obj is mapped in. This pointer is
> not
> + * reference counted.
> + *
> + * A struct drm_gpuvm_bo is not allowed to out-live its
> &drm_gpuvm
> + * context. Implicitly, this is ensured by the fact that the
> driver is
> + * responsible to ensure the VM doesn't contain mappings once
> it's
> + * freed, since a struct drm_gpuvm_bo should be freed once
> the last
> + * mapping being backed by the corresponding buffer object is
> unmapped.
> + */
I don't think the above is completely true. Let's assume in the
!RESV_PROTECTED case that a reference is grabbed on the drm_gpuvm_bo
during an iteration over a list. Then user-space closes the vm and all
vmas are unlinked, but this reference remains but the vm pointer
becomes stale. In the RESV_PROTECTED case this is ensured not to happen
if by the vm->resv being grabbed during unlink, but in the
!RESV_PROTECTED case, the above wording isn't sufficient. The caller
needs to ensure the vm stays alive using some sort of similar rule or
use kref_get_unless_zero() on the vm under the spinlock if
dereferenced.
> + struct drm_gpuvm *vm;
> +
> + /**
> + * @obj: The &drm_gem_object being mapped in @vm. This is a
> reference
> + * counted pointer.
> + */
> + struct drm_gem_object *obj;
> +
> + /**
> + * @kref: The reference count for this &drm_gpuvm_bo.
> + */
> + struct kref kref;
> +
> + /**
> + * @list: Structure containing all &list_heads.
> + */
> + struct {
> + /**
> + * @gpuva: The list of linked &drm_gpuvas.
> + */
> + struct list_head gpuva;
Still missing doc on how the @gpuva stays alive during iteration over
the list?
8<-------------------------------------------------------------
Thanks,
Thomas
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