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@xxxxxxxxx> > Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx> 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; > --- > 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. /Thomas