Messages in this thread | | | Date | Tue, 31 Oct 2023 17:41:37 +0100 | Subject | Re: [PATCH drm-misc-next v7 5/7] drm/gpuvm: track/lock/validate external/evicted objects | From | Danilo Krummrich <> |
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On 10/31/23 12:34, Thomas Hellström wrote: > On Mon, 2023-10-23 at 22:16 +0200, Danilo Krummrich wrote: >> Currently the DRM GPUVM offers common infrastructure to track GPU VA >> allocations and mappings, generically connect GPU VA mappings to >> their >> backing buffers and perform more complex mapping operations on the >> GPU VA >> space. >> >> However, there are more design patterns commonly used by drivers, >> which >> can potentially be generalized in order to make the DRM GPUVM >> represent >> a basis for GPU-VM implementations. In this context, this patch aims >> at generalizing the following elements. >> >> 1) Provide a common dma-resv for GEM objects not being used outside >> of >> this GPU-VM. >> >> 2) Provide tracking of external GEM objects (GEM objects which are >> shared with other GPU-VMs). >> >> 3) Provide functions to efficiently lock all GEM objects dma-resv the >> GPU-VM contains mappings of. >> >> 4) Provide tracking of evicted GEM objects the GPU-VM contains >> mappings >> of, such that validation of evicted GEM objects is accelerated. >> >> 5) Provide some convinience functions for common patterns. >> >> Big thanks to Boris Brezillon for his help to figure out locking for >> drivers updating the GPU VA space within the fence signalling path. >> >> Suggested-by: Matthew Brost <matthew.brost@intel.com> >> Signed-off-by: Danilo Krummrich <dakr@redhat.com> > > The checkpatch.pl warning still persists: > WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP > #627: FILE: drivers/gpu/drm/drm_gpuvm.c:1347: > + return -ENOTSUPP;
Hm, I thought I changed this one. Seems like it slipped through. Gonna fix that.
> >> --- >> drivers/gpu/drm/drm_gpuvm.c | 633 >> ++++++++++++++++++++++++++++++++++++ >> include/drm/drm_gpuvm.h | 250 ++++++++++++++ >> 2 files changed, 883 insertions(+) >> >> diff --git a/drivers/gpu/drm/drm_gpuvm.c >> b/drivers/gpu/drm/drm_gpuvm.c >> index 7f4f5919f84c..01cbeb98755a 100644 >> --- a/drivers/gpu/drm/drm_gpuvm.c >> +++ b/drivers/gpu/drm/drm_gpuvm.c >> @@ -82,6 +82,21 @@ >> * &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. >> + * >> + * &drm_gpuvm_bo structures, since unique for a given &drm_gpuvm, >> are also used >> + * as entry for the &drm_gpuvm's lists of external and evicted >> objects. Those >> + * lists are maintained in order to accelerate locking of dma-resv >> locks and >> + * validation of evicted objects bound in a &drm_gpuvm. For >> instance, all >> + * &drm_gem_object's &dma_resv of a given &drm_gpuvm can be locked >> by calling >> + * drm_gpuvm_exec_lock(). Once locked drivers can call >> drm_gpuvm_validate() in >> + * order to validate all evicted &drm_gem_objects. It is also >> possible to lock >> + * additional &drm_gem_objects by providing the corresponding >> parameters to >> + * drm_gpuvm_exec_lock() as well as open code the &drm_exec loop >> while making >> + * use of helper functions such as drm_gpuvm_prepare_range() or >> + * drm_gpuvm_prepare_objects(). >> + * >> + * Every bound &drm_gem_object is treated as external object when >> its &dma_resv >> + * structure is different than the &drm_gpuvm's common &dma_resv >> structure. >> */ >> >> /** >> @@ -429,6 +444,20 @@ >> * 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. >> + * >> + * The &drm_gpuvm's lists for keeping track of external and evicted >> objects are >> + * protected against concurrent insertion / removal and iteration >> internally. >> + * >> + * However, drivers still need ensure to protect concurrent calls to >> functions >> + * iterating those lists, namely drm_gpuvm_prepare_objects() and >> + * drm_gpuvm_validate(). >> + * >> + * Alternatively, drivers can set the &DRM_GPUVM_RESV_PROTECTED flag >> to indicate >> + * that the corresponding &dma_resv locks are held in order to >> protect the >> + * lists. If &DRM_GPUVM_RESV_PROTECTED is set, internal locking is >> disabled and >> + * the corresponding lockdep checks are enabled. This is an >> optimization for >> + * drivers which are capable of taking the corresponding &dma_resv >> locks and >> + * hence do not require internal locking. >> */ >> >> /** >> @@ -641,6 +670,201 @@ >> * } >> */ >> >> +/** >> + * get_next_vm_bo_from_list() - get the next vm_bo element >> + * @__gpuvm: the &drm_gpuvm >> + * @__list_name: the name of the list we're iterating on >> + * @__local_list: a pointer to the local list used to store already >> iterated items >> + * @__prev_vm_bo: the previous element we got from >> get_next_vm_bo_from_list() >> + * >> + * This helper is here to provide lockless list iteration. Lockless >> as in, the >> + * iterator releases the lock immediately after picking the first >> element from >> + * the list, so list insertion deletion can happen concurrently. >> + * >> + * Elements popped from the original list are kept in a local list, >> so removal >> + * and is_empty checks can still happen while we're iterating the >> list. >> + */ >> +#define get_next_vm_bo_from_list(__gpuvm, __list_name, __local_list, >> __prev_vm_bo) \ >> + ({ >> \ >> + struct drm_gpuvm_bo *__vm_bo = >> NULL; \ >> + >> \ >> + drm_gpuvm_bo_put(__prev_vm_bo); >> \ >> + >> \ >> + spin_lock(&(__gpuvm)- >>> __list_name.lock); \ >> + if (!(__gpuvm)- >>> __list_name.local_list) \ >> + (__gpuvm)->__list_name.local_list = >> __local_list; \ >> + else >> \ >> + drm_WARN_ON((__gpuvm)- >>> drm, \ >> + (__gpuvm)->__list_name.local_list >> != __local_list); \ >> + >> \ >> + while (!list_empty(&(__gpuvm)->__list_name.list)) >> { \ >> + __vm_bo = list_first_entry(&(__gpuvm)- >>> __list_name.list, \ >> + struct >> drm_gpuvm_bo, \ >> + >> list.entry.__list_name); \ >> + if (kref_get_unless_zero(&__vm_bo->kref)) >> { \ >> + list_move_tail(&(__vm_bo)- >>> list.entry.__list_name, \ >> + >> __local_list); \ >> + break; >> \ >> + } else >> { \ >> + list_del_init(&(__vm_bo)- >>> list.entry.__list_name); \ >> + __vm_bo = >> NULL; \ >> + } >> \ >> + } >> \ >> + spin_unlock(&(__gpuvm)- >>> __list_name.lock); \ >> + >> \ >> + __vm_bo; >> \ >> + }) >> + >> +/** >> + * for_each_vm_bo_in_list() - internal vm_bo list iterator >> + * @__gpuvm: the &drm_gpuvm >> + * @__list_name: the name of the list we're iterating on >> + * @__local_list: a pointer to the local list used to store already >> iterated items >> + * @__vm_bo: the struct drm_gpuvm_bo to assign in each iteration >> step >> + * >> + * This helper is here to provide lockless list iteration. Lockless >> as in, the >> + * iterator releases the lock immediately after picking the first >> element from the >> + * list, hence list insertion and deletion can happen concurrently. >> + * >> + * It is not allowed to re-assign the vm_bo pointer from inside this >> loop. >> + * >> + * Typical use: >> + * >> + * struct drm_gpuvm_bo *vm_bo; >> + * LIST_HEAD(my_local_list); >> + * >> + * ret = 0; >> + * for_each_vm_bo_in_list(gpuvm, <list_name>, &my_local_list, >> vm_bo) { >> + * ret = do_something_with_vm_bo(..., vm_bo); >> + * if (ret) >> + * break; >> + * } >> + * // Drop ref in case we break out of the loop. >> + * drm_gpuvm_bo_put(vm_bo); >> + * restore_vm_bo_list(gpuvm, <list_name>, &my_local_list); >> + * >> + * >> + * Only used for internal list iterations, not meant to be exposed >> to the outside >> + * world. >> + */ >> +#define for_each_vm_bo_in_list(__gpuvm, __list_name, __local_list, >> __vm_bo) \ >> + for (__vm_bo = get_next_vm_bo_from_list(__gpuvm, >> __list_name, \ >> + __local_list, >> NULL); \ >> + >> __vm_bo; \ >> + __vm_bo = get_next_vm_bo_from_list(__gpuvm, >> __list_name, \ >> + __local_list, >> __vm_bo)) >> + >> +static void >> +__restore_vm_bo_list(struct drm_gpuvm *gpuvm, spinlock_t *lock, >> + struct list_head *list, struct list_head >> **local_list) >> +{ >> + /* Merge back the two lists, moving local list elements to >> the >> + * head to preserve previous ordering, in case it matters. >> + */ >> + spin_lock(lock); >> + if (*local_list) { >> + list_splice(*local_list, list); >> + *local_list = NULL; >> + } >> + spin_unlock(lock); >> +} >> + >> +/** >> + * restore_vm_bo_list() - move vm_bo elements back to their original >> list >> + * @__gpuvm: the &drm_gpuvm >> + * @__list_name: the name of the list we're iterating on >> + * >> + * When we're done iterating a vm_bo list, we should call >> restore_vm_bo_list() >> + * to restore the original state and let new iterations take place. >> + */ >> +#define restore_vm_bo_list(__gpuvm, >> __list_name) \ >> + __restore_vm_bo_list((__gpuvm), &(__gpuvm)- >>> __list_name.lock, \ >> + &(__gpuvm)- >>> __list_name.list, \ >> + &(__gpuvm)->__list_name.local_list) >> + >> +static void >> +cond_spin_lock(spinlock_t *lock, bool cond) >> +{ >> + if (cond) >> + spin_lock(lock); >> +} >> + >> +static void >> +cond_spin_unlock(spinlock_t *lock, bool cond) >> +{ >> + if (cond) >> + spin_unlock(lock); >> +} >> + >> +static void >> +__drm_gpuvm_bo_list_add(struct drm_gpuvm *gpuvm, spinlock_t *lock, >> + struct list_head *entry, struct list_head >> *list) >> +{ >> + cond_spin_lock(lock, !!lock); >> + if (list_empty(entry)) >> + list_add_tail(entry, list); >> + cond_spin_unlock(lock, !!lock); >> +} >> + >> +/** >> + * drm_gpuvm_bo_list_add() - insert a vm_bo into the given list >> + * @__vm_bo: the &drm_gpuvm_bo >> + * @__list_name: the name of the list to insert into >> + * @__lock: whether to lock with the internal spinlock >> + * >> + * Inserts the given @__vm_bo into the list specified by >> @__list_name. >> + */ >> +#define drm_gpuvm_bo_list_add(__vm_bo, __list_name, >> __lock) \ >> + __drm_gpuvm_bo_list_add((__vm_bo)- >>> vm, \ >> + __lock ? &(__vm_bo)->vm- >>> __list_name.lock : \ >> + >> NULL, \ >> + &(__vm_bo)- >>> list.entry.__list_name, \ >> + &(__vm_bo)->vm->__list_name.list) >> + >> +static void >> +__drm_gpuvm_bo_list_del(struct drm_gpuvm *gpuvm, spinlock_t *lock, >> + struct list_head *entry, bool init) >> +{ >> + cond_spin_lock(lock, !!lock); >> + if (init) { >> + if (!list_empty(entry)) >> + list_del_init(entry); >> + } else { >> + list_del(entry); >> + } >> + cond_spin_unlock(lock, !!lock); >> +} >> + >> +/** >> + * drm_gpuvm_bo_list_del_init() - remove a vm_bo from the given list >> + * @__vm_bo: the &drm_gpuvm_bo >> + * @__list_name: the name of the list to insert into >> + * @__lock: whether to lock with the internal spinlock >> + * >> + * Removes the given @__vm_bo from the list specified by >> @__list_name. >> + */ >> +#define drm_gpuvm_bo_list_del_init(__vm_bo, __list_name, >> __lock) \ >> + __drm_gpuvm_bo_list_del((__vm_bo)- >>> vm, \ >> + __lock ? &(__vm_bo)->vm- >>> __list_name.lock : \ >> + >> NULL, \ >> + &(__vm_bo)- >>> list.entry.__list_name, \ >> + true) >> + >> +/** >> + * drm_gpuvm_bo_list_del() - remove a vm_bo from the given list >> + * @__vm_bo: the &drm_gpuvm_bo >> + * @__list_name: the name of the list to insert into >> + * @__lock: whether to lock with the internal spinlock >> + * >> + * Removes the given @__vm_bo from the list specified by >> @__list_name. >> + */ >> +#define drm_gpuvm_bo_list_del(__vm_bo, __list_name, >> __lock) \ >> + __drm_gpuvm_bo_list_del((__vm_bo)- >>> vm, \ >> + __lock ? &(__vm_bo)->vm- >>> __list_name.lock : \ >> + >> NULL, \ >> + &(__vm_bo)- >>> list.entry.__list_name, \ >> + false) >> + >> #define to_drm_gpuva(__node) container_of((__node), struct >> drm_gpuva, rb.node) >> >> #define GPUVA_START(node) ((node)->va.addr) >> @@ -763,6 +987,12 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, const >> char *name, >> gpuvm->rb.tree = RB_ROOT_CACHED; >> INIT_LIST_HEAD(&gpuvm->rb.list); >> >> + INIT_LIST_HEAD(&gpuvm->extobj.list); >> + spin_lock_init(&gpuvm->extobj.lock); >> + >> + INIT_LIST_HEAD(&gpuvm->evict.list); >> + spin_lock_init(&gpuvm->evict.lock); >> + >> gpuvm->name = name ? name : "unknown"; >> gpuvm->flags = flags; >> gpuvm->ops = ops; >> @@ -805,10 +1035,352 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm) >> drm_WARN(gpuvm->drm, !RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root), >> "GPUVA tree is not empty, potentially leaking >> memory.\n"); >> >> + drm_WARN(gpuvm->drm, !list_empty(&gpuvm->extobj.list), >> + "Extobj list should be empty.\n"); >> + drm_WARN(gpuvm->drm, !list_empty(&gpuvm->evict.list), >> + "Evict list should be empty.\n"); >> + >> drm_gem_object_put(gpuvm->r_obj); >> } >> EXPORT_SYMBOL_GPL(drm_gpuvm_destroy); >> >> +static int >> +__drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm, >> + struct drm_exec *exec, >> + unsigned int num_fences) >> +{ >> + struct drm_gpuvm_bo *vm_bo; >> + LIST_HEAD(extobjs); >> + int ret = 0; >> + >> + for_each_vm_bo_in_list(gpuvm, extobj, &extobjs, vm_bo) { >> + ret = drm_exec_prepare_obj(exec, vm_bo->obj, >> num_fences); >> + if (ret) >> + break; >> + } >> + /* Drop ref in case we break out of the loop. */ >> + drm_gpuvm_bo_put(vm_bo); >> + restore_vm_bo_list(gpuvm, extobj); >> + >> + return ret; >> +} >> + >> +static int >> +drm_gpuvm_prepare_objects_locked(struct drm_gpuvm *gpuvm, >> + struct drm_exec *exec, >> + unsigned int num_fences) >> +{ >> + struct drm_gpuvm_bo *vm_bo; >> + int ret = 0; >> + >> + drm_gpuvm_resv_assert_held(gpuvm); >> + list_for_each_entry(vm_bo, &gpuvm->extobj.list, >> list.entry.extobj) { >> + ret = drm_exec_prepare_obj(exec, vm_bo->obj, >> num_fences); >> + if (ret) >> + break; >> + >> + if (vm_bo->evicted) >> + drm_gpuvm_bo_list_add(vm_bo, evict, false); >> + } >> + >> + return ret; >> +} >> + >> +/** >> + * drm_gpuvm_prepare_objects() - prepare all assoiciated BOs >> + * @gpuvm: the &drm_gpuvm >> + * @exec: the &drm_exec locking context >> + * @num_fences: the amount of &dma_fences to reserve >> + * >> + * Calls drm_exec_prepare_obj() for all &drm_gem_objects the given >> + * &drm_gpuvm contains mappings of. >> + * >> + * Using this function directly, it is the drivers responsibility to >> call >> + * drm_exec_init() and drm_exec_fini() accordingly. >> + * >> + * Note: This function is safe against concurrent insertion and >> removal of >> + * external objects, however it is not safe against concurrent usage >> itself. >> + * >> + * Drivers need to make sure to protect this case with either an >> outer VM lock >> + * or by calling drm_gpuvm_prepare_vm() before this function within >> the >> + * drm_exec_until_all_locked() loop, such that the GPUVM's dma-resv >> lock ensures >> + * mutual exclusion. >> + * >> + * Returns: 0 on success, negative error code on failure. > > s/Returns:/Return:/g > > Otherwise LGTM.
Sounds like you want to offer your RB? :)
> > /Thomas > >
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