From 94bc2249f08e141fb4aa120bfdc392c7a5e78211 Mon Sep 17 00:00:00 2001 From: Danilo Krummrich Date: Wed, 8 Nov 2023 01:12:40 +0100 Subject: drm/gpuvm: add an abstraction for a VM / BO combination MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Acked-by: Christian König Reviewed-by: Thomas Hellström Reviewed-by: Boris Brezillon Signed-off-by: Danilo Krummrich Link: https://patchwork.freedesktop.org/patch/msgid/20231108001259.15123-11-dakr@redhat.com --- drivers/gpu/drm/drm_gpuvm.c | 340 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 293 insertions(+), 47 deletions(-) (limited to 'drivers/gpu/drm/drm_gpuvm.c') diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c index ef968eba6fe6..7e193bca8bab 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; * } * @@ -815,6 +850,199 @@ drm_gpuvm_put(struct drm_gpuvm *gpuvm) } EXPORT_SYMBOL_GPL(drm_gpuvm_put); +/** + * 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 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 = drm_gpuvm_get(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_gpuvm_put(gpuvm); + 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 drop to zero the caller must + * hold the dma-resv or driver specific GEM gpuva lock. + * + * This function may only be called from non-atomic context. + */ +void +drm_gpuvm_bo_put(struct drm_gpuvm_bo *vm_bo) +{ + might_sleep(); + + 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) @@ -916,24 +1144,33 @@ 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); @@ -944,20 +1181,31 @@ 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); @@ -1102,10 +1350,10 @@ 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); @@ -1747,9 +1995,8 @@ err_free_ops: 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. @@ -1766,15 +2013,14 @@ 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) @@ -1782,8 +2028,8 @@ 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; @@ -1797,10 +2043,10 @@ 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 -- cgit v1.2.3