Nouveau - Oct 2023 - [PATCH drm-misc-next v6 4/6] drm/gpuvm: track/lock/validate external/evicted objects

On 10/9/23 15:36, Thomas Hellstr?m wrote:
> 
> On 10/9/23 01:32, 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 at intel.com>
>> Signed-off-by: Danilo Krummrich <dakr at redhat.com>
>> ---
>> ? drivers/gpu/drm/drm_gpuvm.c | 646
++++++++++++++++++++++++++++++++++++
>> ? include/drm/drm_gpuvm.h???? | 246 ++++++++++++++
>> ? 2 files changed, 892 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/drm_gpuvm.c b/drivers/gpu/drm/drm_gpuvm.c
>> index 28282283ddaf..6977bd30eca5 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
>> + * list 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 +670,195 @@
>> ?? *??? }
>> ?? */
>> +/**
>> + * get_next_vm_bo_from_list() - get the next vm_bo element
>> + * @__gpuvm: The GPU VM
>> + * @__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
drm_gpuvm_get_next_cached_vm_bo()
>> + *
>> + * 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??????????????????????????????????? \
>> +??????????? WARN_ON((__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
>> + *
>> + * 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;
>> + *??? }
>> + *??? 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 GPU VM
>> + * @__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)
>> @@ -760,6 +978,12 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct
drm_gem_object *r_obj,
>> ????? 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);
>> +
>> ????? drm_gpuvm_check_overflow(start_offset, range);
>> ????? gpuvm->mm_start = start_offset;
>> ????? gpuvm->mm_range = range;
>> @@ -802,10 +1026,372 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>> ????? WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
>> ?????????? "GPUVA tree is not empty, potentially leaking
memory.\n");
>> +??? WARN(!list_empty(&gpuvm->extobj.list), "Extobj list
should be empty.\n");
>> +??? WARN(!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);
> 
> Clear vm_bo->evicted here?
Why? It's still evicted, hence why not indicate it? It could be useful for a
validate_range() use case.
> 
> 
>> +??? }
>> +
>> +??? 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.
>> + */
>> +int
>> +drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
>> +????????????? struct drm_exec *exec,
>> +????????????? unsigned int num_fences)
>> +{
>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>> +??????? return drm_gpuvm_prepare_objects_locked(gpuvm, exec,
>> +??????????????????????????? num_fences);
>> +??? else
>> +??????? return __drm_gpuvm_prepare_objects(gpuvm, exec, num_fences);
>> +
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_objects);
>> +
>> +/**
>> + * drm_gpuvm_prepare_range() - prepare all BOs mapped within a given
range
>> + * @gpuvm: the &drm_gpuvm
>> + * @exec: the &drm_exec locking context
>> + * @addr: the start address within the VA space
>> + * @range: the range to iterate within the VA space
>> + * @num_fences: the amount of &dma_fences to reserve
>> + *
>> + * Calls drm_exec_prepare_obj() for all &drm_gem_objects mapped
between @addr
>> + * and @addr + @range.
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuvm_prepare_range(struct drm_gpuvm *gpuvm, struct drm_exec
*exec,
>> +??????????? u64 addr, u64 range, unsigned int num_fences)
>> +{
>> +??? struct drm_gpuva *va;
>> +??? u64 end = addr + range;
>> +??? int ret;
>> +
>> +??? drm_gpuvm_for_each_va_range(va, gpuvm, addr, end) {
>> +??????? struct drm_gem_object *obj = va->gem.obj;
>> +
>> +??????? ret = drm_exec_prepare_obj(exec, obj, num_fences);
>> +??????? if (ret)
>> +??????????? return ret;
>> +??? }
>> +
>> +??? return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_range);
>> +
>> +/**
>> + * drm_gpuvm_exec_lock() - lock all dma-resv of all assoiciated BOs
>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>> + * @num_fences: the amount of &dma_fences to reserve
>> + * @interruptible: sleep interruptible if waiting
>> + *
>> + * Acquires all dma-resv locks of all &drm_gem_objects the given
>> + * &drm_gpuvm contains mappings of.
>> + *
>> + * Addionally, when calling this function with struct
drm_gpuvm_exec::extra
>> + * being set the driver receives the given @fn callback to lock
additional
>> + * dma-resv in the context of the &drm_gpuvm_exec instance.
Typically, drivers
>> + * would call drm_exec_prepare_obj() from within this callback.
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuvm_exec_lock(struct drm_gpuvm_exec *vm_exec,
>> +??????????? unsigned int num_fences,
>> +??????????? bool interruptible)
>> +{
>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>> +??? struct drm_exec *exec = &vm_exec->exec;
>> +??? uint32_t flags;
>> +??? int ret;
>> +
>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>> +
>> +??? drm_exec_init(exec, flags);
>> +
>> +??? drm_exec_until_all_locked(exec) {
>> +??????? ret = drm_gpuvm_prepare_vm(gpuvm, exec, num_fences);
>> +??????? drm_exec_retry_on_contention(exec);
>> +??????? if (ret)
>> +??????????? goto err;
>> +
>> +??????? ret = drm_gpuvm_prepare_objects(gpuvm, exec, num_fences);
>> +??????? drm_exec_retry_on_contention(exec);
>> +??????? if (ret)
>> +??????????? goto err;
>> +
>> +??????? if (vm_exec->extra.fn) {
>> +??????????? ret = vm_exec->extra.fn(vm_exec, num_fences);
>> +??????????? drm_exec_retry_on_contention(exec);
>> +??????????? if (ret)
>> +??????????????? goto err;
>> +??????? }
>> +??? }
>> +
>> +??? return 0;
>> +
>> +err:
>> +??? drm_exec_fini(exec);
>> +??? return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock);
>> +
>> +static int
>> +fn_lock_array(struct drm_gpuvm_exec *vm_exec, unsigned int num_fences)
>> +{
>> +??? struct {
>> +??????? struct drm_gem_object **objs;
>> +??????? unsigned int num_objs;
>> +??? } *args = vm_exec->extra.priv;
>> +
>> +??? return drm_exec_prepare_array(&vm_exec->exec,
args->objs,
>> +????????????????????? args->num_objs, num_fences);
>> +}
>> +
>> +/**
>> + * drm_gpuvm_exec_lock_array() - lock all dma-resv of all assoiciated
BOs
>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>> + * @objs: additional &drm_gem_objects to lock
>> + * @num_objs: the number of additional &drm_gem_objects to lock
>> + * @num_fences: the amount of &dma_fences to reserve
>> + * @interruptible: sleep interruptible if waiting
>> + *
>> + * Acquires all dma-resv locks of all &drm_gem_objects the given
&drm_gpuvm
>> + * contains mappings of, plus the ones given through @objs.
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuvm_exec_lock_array(struct drm_gpuvm_exec *vm_exec,
>> +????????????? struct drm_gem_object **objs,
>> +????????????? unsigned int num_objs,
>> +????????????? unsigned int num_fences,
>> +????????????? bool interruptible)
>> +{
>> +??? struct {
>> +??????? struct drm_gem_object **objs;
>> +??????? unsigned int num_objs;
>> +??? } args;
>> +
>> +??? args.objs = objs;
>> +??? args.num_objs = num_objs;
>> +
>> +??? vm_exec->extra.fn = fn_lock_array;
>> +??? vm_exec->extra.priv = &args;
>> +
>> +??? return drm_gpuvm_exec_lock(vm_exec, num_fences, interruptible);
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_array);
>> +
>> +/**
>> + * drm_gpuvm_exec_lock_range() - prepare all BOs mapped within a given
range
>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>> + * @addr: the start address within the VA space
>> + * @range: the range to iterate within the VA space
>> + * @num_fences: the amount of &dma_fences to reserve
>> + * @interruptible: sleep interruptible if waiting
>> + *
>> + * Acquires all dma-resv locks of all &drm_gem_objects mapped
between @addr and
>> + * @addr + @range.
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuvm_exec_lock_range(struct drm_gpuvm_exec *vm_exec,
>> +????????????? u64 addr, u64 range,
>> +????????????? unsigned int num_fences,
>> +????????????? bool interruptible)
>> +{
>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>> +??? struct drm_exec *exec = &vm_exec->exec;
>> +??? uint32_t flags;
>> +??? int ret;
>> +
>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>> +
>> +??? drm_exec_init(exec, flags);
>> +
>> +??? drm_exec_until_all_locked(exec) {
>> +??????? ret = drm_gpuvm_prepare_range(gpuvm, exec, addr, range,
>> +????????????????????????? num_fences);
>> +??????? drm_exec_retry_on_contention(exec);
>> +??????? if (ret)
>> +??????????? goto err;
>> +??? }
>> +
>> +??? return ret;
>> +
>> +err:
>> +??? drm_exec_fini(exec);
>> +??? return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_range);
>> +
>> +static int
>> +__drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec *exec)
>> +{
>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>> +??? struct drm_gpuvm_bo *vm_bo;
>> +??? LIST_HEAD(evict);
>> +??? int ret = 0;
>> +
>> +??? for_each_vm_bo_in_list(gpuvm, evict, &evict, vm_bo) {
>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>> +??????? if (ret)
>> +??????????? break;
>> +??? }
>> +??? /* Drop ref in case we break out of the loop. */
>> +??? drm_gpuvm_bo_put(vm_bo);
>> +??? restore_vm_bo_list(gpuvm, evict);
>> +
>> +??? return ret;
>> +}
>> +
>> +static int
>> +drm_gpuvm_validate_locked(struct drm_gpuvm *gpuvm, struct drm_exec
*exec)
>> +{
>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>> +??? struct drm_gpuvm_bo *vm_bo, *next;
>> +??? int ret = 0;
>> +
>> +??? drm_gpuvm_resv_assert_held(gpuvm);
>> +
>> +??? /* Iterate list safely, drivers typically remove the current entry
from
>> +???? * their drm_gpuvm_ops::vm_bo_validate callback. Drivers might
also
>> +???? * re-add the entry on failure; this is safe since on failure we
break
>> +???? * out of the loop.
>> +???? */
>> +??? list_for_each_entry_safe(vm_bo, next, &gpuvm->evict.list,
>> +???????????????? list.entry.evict) {
>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>> +??????? if (ret)
>> +??????????? break;
>> +??? }
>> +
>> +??? return ret;
>> +}
>> +
>> +/**
>> + * drm_gpuvm_validate() - validate all BOs marked as evicted
>> + * @gpuvm: the &drm_gpuvm to validate evicted BOs
>> + * @exec: the &drm_exec instance used for locking the GPUVM
>> + *
>> + * Calls the &drm_gpuvm_ops::vm_bo_validate callback for all
evicted buffer
>> + * objects being mapped in the given &drm_gpuvm.
>> + *
>> + * Returns: 0 on success, negative error code on failure.
>> + */
>> +int
>> +drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec *exec)
>> +{
>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>> +
>> +??? if (unlikely(!ops || !ops->vm_bo_validate))
>> +??????? return -ENOTSUPP;
>> +
>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>> +??????? return drm_gpuvm_validate_locked(gpuvm, exec);
>> +??? else
>> +??????? return __drm_gpuvm_validate(gpuvm, exec);
>> +
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_validate);
>> +
>> +/**
>> + * drm_gpuvm_resv_add_fence - add fence to private and all extobj
>> + * dma-resv
>> + * @gpuvm: the &drm_gpuvm to add a fence to
>> + * @exec: the &drm_exec locking context
>> + * @fence: fence to add
>> + * @private_usage: private dma-resv usage
>> + * @extobj_usage: extobj dma-resv usage
>> + */
>> +void
>> +drm_gpuvm_resv_add_fence(struct drm_gpuvm *gpuvm,
>> +???????????? struct drm_exec *exec,
>> +???????????? struct dma_fence *fence,
>> +???????????? enum dma_resv_usage private_usage,
>> +???????????? enum dma_resv_usage extobj_usage)
>> +{
>> +??? struct drm_gem_object *obj;
>> +??? unsigned long index;
>> +
>> +??? drm_exec_for_each_locked_object(exec, index, obj) {
>> +??????? dma_resv_assert_held(obj->resv);
>> +??????? dma_resv_add_fence(obj->resv, fence,
>> +?????????????????? drm_gpuvm_is_extobj(gpuvm, obj) ?
>> +?????????????????? private_usage : extobj_usage);
>> +??? }
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_resv_add_fence);
>> +
>> ? /**
>> ?? * drm_gpuvm_bo_create() - create a new instance of struct
drm_gpuvm_bo
>> ?? * @gpuvm: The &drm_gpuvm the @obj is mapped in.
>> @@ -838,6 +1424,9 @@ drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
>> ????? INIT_LIST_HEAD(&vm_bo->list.gpuva);
>> ????? INIT_LIST_HEAD(&vm_bo->list.entry.gem);
>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.extobj);
>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.evict);
>> +
>> ????? drm_gem_object_get(obj);
>> ????? return vm_bo;
>> @@ -858,6 +1447,9 @@ drm_gpuvm_bo_destroy(struct kref *kref)
>> ????? if (!lock)
>> ????????? drm_gpuvm_resv_assert_held(gpuvm);
>> +??? drm_gpuvm_bo_list_del(vm_bo, extobj, lock);
>> +??? drm_gpuvm_bo_list_del(vm_bo, evict, lock);
>> +
>> ????? list_del(&vm_bo->list.entry.gem);
>> ????? drm_gem_object_put(obj);
>> @@ -994,6 +1586,60 @@ drm_gpuvm_bo_obtain_prealloc(struct drm_gpuvm_bo
*__vm_bo)
>> ? }
>> ? EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_prealloc);
>> +/**
>> + * drm_gpuvm_bo_extobj_add() - adds the &drm_gpuvm_bo to its
&drm_gpuvm's
>> + * extobj list
>> + * @vm_bo: The &drm_gpuvm_bo to add to its &drm_gpuvm's
the extobj list.
>> + *
>> + * Adds the given @vm_bo to its &drm_gpuvm's extobj list if
not on the list
>> + * already and if the corresponding &drm_gem_object is an external
object,
>> + * actually.
>> + */
>> +void
>> +drm_gpuvm_bo_extobj_add(struct drm_gpuvm_bo *vm_bo)
>> +{
>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>> +
>> +??? if (!lock)
>> +??????? drm_gpuvm_resv_assert_held(gpuvm);
>> +
>> +??? if (drm_gpuvm_is_extobj(gpuvm, vm_bo->obj))
>> +??????? drm_gpuvm_bo_list_add(vm_bo, extobj, lock);
>> +}
>> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_extobj_add);
>> +
>> +/**
>> + * drm_gpuvm_bo_evict() - add / remove a &drm_gpuvm_bo to / from
the &drm_gpuvms
>> + * evicted list
>> + * @vm_bo: the &drm_gpuvm_bo to add or remove
>> + * @evict: indicates whether the object is evicted
>> + *
>> + * Adds a &drm_gpuvm_bo to or removes it from the &drm_gpuvms
evicted list.
>> + */
>> +void
>> +drm_gpuvm_bo_evict(struct drm_gpuvm_bo *vm_bo, bool evict)
>> +{
>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>> +??? struct drm_gem_object *obj = vm_bo->obj;
>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>> +
>> +??? dma_resv_assert_held(obj->resv);
>> +
>> +??? if (drm_gpuvm_is_extobj(gpuvm, obj)) {
>> +??????? vm_bo->evicted = evict;
> Does the lock case also need this?
It doesn't need it by itself, but since we have drm_gpuvm_bo::evicted now, I
want it to
consistently indicate whether the BO is evicted or not.
>> +
>> +??????? if (!lock)
>> +??????????? return;
> 
> Here the !lock case can not remove the gpuvm_bo from the list?
You mean because we'd expect that drm_gpuvm_bo_evict(vm_bo, false) can only
be called from
within gpuvm_validate(), which requires the VM's resv lock? What if there is
a ttm_validate()
call for only this GEM obj?

My idea was to remove VM_BOs from the evicted list in gpuvm_validate() directly,
but I'm afraid
I forgot that.
> 
> Small patch here that I've been using for xe:
> 
> https://patchwork.freedesktop.org/patch/561545/?series=124817&rev=1
> 
> Thanks,
> 
> Thomas
> 
>

On 10/9/23 16:45, Danilo Krummrich wrote:
> On 10/9/23 15:36, Thomas Hellstr?m wrote:
>>
>> On 10/9/23 01:32, 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 at intel.com>
>>> Signed-off-by: Danilo Krummrich <dakr at redhat.com>
>>> ---
>>> ? drivers/gpu/drm/drm_gpuvm.c | 646
++++++++++++++++++++++++++++++++++++
>>> ? include/drm/drm_gpuvm.h???? | 246 ++++++++++++++
>>> ? 2 files changed, 892 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_gpuvm.c
b/drivers/gpu/drm/drm_gpuvm.c
>>> index 28282283ddaf..6977bd30eca5 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
>>> + * list 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 +670,195 @@
>>> ?? *??? }
>>> ?? */
>>> +/**
>>> + * get_next_vm_bo_from_list() - get the next vm_bo element
>>> + * @__gpuvm: The GPU VM
>>> + * @__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
drm_gpuvm_get_next_cached_vm_bo()
>>> + *
>>> + * 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??????????????????????????????????? \
>>> +??????????? WARN_ON((__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
>>> + *
>>> + * 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;
>>> + *??? }
>>> + *??? 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 GPU VM
>>> + * @__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)
>>> @@ -760,6 +978,12 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct
drm_gem_object *r_obj,
>>> ????? 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);
>>> +
>>> ????? drm_gpuvm_check_overflow(start_offset, range);
>>> ????? gpuvm->mm_start = start_offset;
>>> ????? gpuvm->mm_range = range;
>>> @@ -802,10 +1026,372 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>>> ????? WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
>>> ?????????? "GPUVA tree is not empty, potentially leaking
memory.\n");
>>> +??? WARN(!list_empty(&gpuvm->extobj.list), "Extobj
list should be empty.\n");
>>> +??? WARN(!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);
>>
>> Clear vm_bo->evicted here?
> 
> Why? It's still evicted, hence why not indicate it? It could be useful
for a
> validate_range() use case.
> 
>>
>>
>>> +??? }
>>> +
>>> +??? 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.
>>> + */
>>> +int
>>> +drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
>>> +????????????? struct drm_exec *exec,
>>> +????????????? unsigned int num_fences)
>>> +{
>>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>>> +??????? return drm_gpuvm_prepare_objects_locked(gpuvm, exec,
>>> +??????????????????????????? num_fences);
>>> +??? else
>>> +??????? return __drm_gpuvm_prepare_objects(gpuvm, exec,
num_fences);
>>> +
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_objects);
>>> +
>>> +/**
>>> + * drm_gpuvm_prepare_range() - prepare all BOs mapped within a
given range
>>> + * @gpuvm: the &drm_gpuvm
>>> + * @exec: the &drm_exec locking context
>>> + * @addr: the start address within the VA space
>>> + * @range: the range to iterate within the VA space
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + *
>>> + * Calls drm_exec_prepare_obj() for all &drm_gem_objects
mapped between @addr
>>> + * and @addr + @range.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_prepare_range(struct drm_gpuvm *gpuvm, struct drm_exec
*exec,
>>> +??????????? u64 addr, u64 range, unsigned int num_fences)
>>> +{
>>> +??? struct drm_gpuva *va;
>>> +??? u64 end = addr + range;
>>> +??? int ret;
>>> +
>>> +??? drm_gpuvm_for_each_va_range(va, gpuvm, addr, end) {
>>> +??????? struct drm_gem_object *obj = va->gem.obj;
>>> +
>>> +??????? ret = drm_exec_prepare_obj(exec, obj, num_fences);
>>> +??????? if (ret)
>>> +??????????? return ret;
>>> +??? }
>>> +
>>> +??? return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_range);
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock() - lock all dma-resv of all assoiciated
BOs
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects the
given
>>> + * &drm_gpuvm contains mappings of.
>>> + *
>>> + * Addionally, when calling this function with struct
drm_gpuvm_exec::extra
>>> + * being set the driver receives the given @fn callback to lock
additional
>>> + * dma-resv in the context of the &drm_gpuvm_exec instance.
Typically, drivers
>>> + * would call drm_exec_prepare_obj() from within this callback.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock(struct drm_gpuvm_exec *vm_exec,
>>> +??????????? unsigned int num_fences,
>>> +??????????? bool interruptible)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>>> +??? struct drm_exec *exec = &vm_exec->exec;
>>> +??? uint32_t flags;
>>> +??? int ret;
>>> +
>>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>>> +
>>> +??? drm_exec_init(exec, flags);
>>> +
>>> +??? drm_exec_until_all_locked(exec) {
>>> +??????? ret = drm_gpuvm_prepare_vm(gpuvm, exec, num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +
>>> +??????? ret = drm_gpuvm_prepare_objects(gpuvm, exec, num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +
>>> +??????? if (vm_exec->extra.fn) {
>>> +??????????? ret = vm_exec->extra.fn(vm_exec, num_fences);
>>> +??????????? drm_exec_retry_on_contention(exec);
>>> +??????????? if (ret)
>>> +??????????????? goto err;
>>> +??????? }
>>> +??? }
>>> +
>>> +??? return 0;
>>> +
>>> +err:
>>> +??? drm_exec_fini(exec);
>>> +??? return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock);
>>> +
>>> +static int
>>> +fn_lock_array(struct drm_gpuvm_exec *vm_exec, unsigned int
num_fences)
>>> +{
>>> +??? struct {
>>> +??????? struct drm_gem_object **objs;
>>> +??????? unsigned int num_objs;
>>> +??? } *args = vm_exec->extra.priv;
>>> +
>>> +??? return drm_exec_prepare_array(&vm_exec->exec,
args->objs,
>>> +????????????????????? args->num_objs, num_fences);
>>> +}
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock_array() - lock all dma-resv of all
assoiciated BOs
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @objs: additional &drm_gem_objects to lock
>>> + * @num_objs: the number of additional &drm_gem_objects to
lock
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects the
given &drm_gpuvm
>>> + * contains mappings of, plus the ones given through @objs.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock_array(struct drm_gpuvm_exec *vm_exec,
>>> +????????????? struct drm_gem_object **objs,
>>> +????????????? unsigned int num_objs,
>>> +????????????? unsigned int num_fences,
>>> +????????????? bool interruptible)
>>> +{
>>> +??? struct {
>>> +??????? struct drm_gem_object **objs;
>>> +??????? unsigned int num_objs;
>>> +??? } args;
>>> +
>>> +??? args.objs = objs;
>>> +??? args.num_objs = num_objs;
>>> +
>>> +??? vm_exec->extra.fn = fn_lock_array;
>>> +??? vm_exec->extra.priv = &args;
>>> +
>>> +??? return drm_gpuvm_exec_lock(vm_exec, num_fences,
interruptible);
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_array);
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock_range() - prepare all BOs mapped within a
given range
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @addr: the start address within the VA space
>>> + * @range: the range to iterate within the VA space
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects mapped
between @addr and
>>> + * @addr + @range.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock_range(struct drm_gpuvm_exec *vm_exec,
>>> +????????????? u64 addr, u64 range,
>>> +????????????? unsigned int num_fences,
>>> +????????????? bool interruptible)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>>> +??? struct drm_exec *exec = &vm_exec->exec;
>>> +??? uint32_t flags;
>>> +??? int ret;
>>> +
>>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>>> +
>>> +??? drm_exec_init(exec, flags);
>>> +
>>> +??? drm_exec_until_all_locked(exec) {
>>> +??????? ret = drm_gpuvm_prepare_range(gpuvm, exec, addr, range,
>>> +????????????????????????? num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +??? }
>>> +
>>> +??? return ret;
>>> +
>>> +err:
>>> +??? drm_exec_fini(exec);
>>> +??? return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_range);
>>> +
>>> +static int
>>> +__drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec
*exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +??? struct drm_gpuvm_bo *vm_bo;
>>> +??? LIST_HEAD(evict);
>>> +??? int ret = 0;
>>> +
>>> +??? for_each_vm_bo_in_list(gpuvm, evict, &evict, vm_bo) {
>>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>>> +??????? if (ret)
>>> +??????????? break;
>>> +??? }
>>> +??? /* Drop ref in case we break out of the loop. */
>>> +??? drm_gpuvm_bo_put(vm_bo);
>>> +??? restore_vm_bo_list(gpuvm, evict);
>>> +
>>> +??? return ret;
>>> +}
>>> +
>>> +static int
>>> +drm_gpuvm_validate_locked(struct drm_gpuvm *gpuvm, struct drm_exec
*exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +??? struct drm_gpuvm_bo *vm_bo, *next;
>>> +??? int ret = 0;
>>> +
>>> +??? drm_gpuvm_resv_assert_held(gpuvm);
>>> +
>>> +??? /* Iterate list safely, drivers typically remove the current
entry from
>>> +???? * their drm_gpuvm_ops::vm_bo_validate callback. Drivers might
also
>>> +???? * re-add the entry on failure; this is safe since on failure
we break
>>> +???? * out of the loop.
>>> +???? */
>>> +??? list_for_each_entry_safe(vm_bo, next,
&gpuvm->evict.list,
>>> +???????????????? list.entry.evict) {
>>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>>> +??????? if (ret)
>>> +??????????? break;
>>> +??? }
>>> +
>>> +??? return ret;
>>> +}
>>> +
>>> +/**
>>> + * drm_gpuvm_validate() - validate all BOs marked as evicted
>>> + * @gpuvm: the &drm_gpuvm to validate evicted BOs
>>> + * @exec: the &drm_exec instance used for locking the GPUVM
>>> + *
>>> + * Calls the &drm_gpuvm_ops::vm_bo_validate callback for all
evicted buffer
>>> + * objects being mapped in the given &drm_gpuvm.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec *exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +
>>> +??? if (unlikely(!ops || !ops->vm_bo_validate))
>>> +??????? return -ENOTSUPP;
>>> +
>>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>>> +??????? return drm_gpuvm_validate_locked(gpuvm, exec);
>>> +??? else
>>> +??????? return __drm_gpuvm_validate(gpuvm, exec);
>>> +
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_validate);
>>> +
>>> +/**
>>> + * drm_gpuvm_resv_add_fence - add fence to private and all extobj
>>> + * dma-resv
>>> + * @gpuvm: the &drm_gpuvm to add a fence to
>>> + * @exec: the &drm_exec locking context
>>> + * @fence: fence to add
>>> + * @private_usage: private dma-resv usage
>>> + * @extobj_usage: extobj dma-resv usage
>>> + */
>>> +void
>>> +drm_gpuvm_resv_add_fence(struct drm_gpuvm *gpuvm,
>>> +???????????? struct drm_exec *exec,
>>> +???????????? struct dma_fence *fence,
>>> +???????????? enum dma_resv_usage private_usage,
>>> +???????????? enum dma_resv_usage extobj_usage)
>>> +{
>>> +??? struct drm_gem_object *obj;
>>> +??? unsigned long index;
>>> +
>>> +??? drm_exec_for_each_locked_object(exec, index, obj) {
>>> +??????? dma_resv_assert_held(obj->resv);
>>> +??????? dma_resv_add_fence(obj->resv, fence,
>>> +?????????????????? drm_gpuvm_is_extobj(gpuvm, obj) ?
>>> +?????????????????? private_usage : extobj_usage);
>>> +??? }
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_resv_add_fence);
>>> +
>>> ? /**
>>> ?? * drm_gpuvm_bo_create() - create a new instance of struct
drm_gpuvm_bo
>>> ?? * @gpuvm: The &drm_gpuvm the @obj is mapped in.
>>> @@ -838,6 +1424,9 @@ drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
>>> ????? INIT_LIST_HEAD(&vm_bo->list.gpuva);
>>> ????? INIT_LIST_HEAD(&vm_bo->list.entry.gem);
>>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.extobj);
>>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.evict);
>>> +
>>> ????? drm_gem_object_get(obj);
>>> ????? return vm_bo;
>>> @@ -858,6 +1447,9 @@ drm_gpuvm_bo_destroy(struct kref *kref)
>>> ????? if (!lock)
>>> ????????? drm_gpuvm_resv_assert_held(gpuvm);
>>> +??? drm_gpuvm_bo_list_del(vm_bo, extobj, lock);
>>> +??? drm_gpuvm_bo_list_del(vm_bo, evict, lock);
>>> +
>>> ????? list_del(&vm_bo->list.entry.gem);
>>> ????? drm_gem_object_put(obj);
>>> @@ -994,6 +1586,60 @@ drm_gpuvm_bo_obtain_prealloc(struct
drm_gpuvm_bo *__vm_bo)
>>> ? }
>>> ? EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_prealloc);
>>> +/**
>>> + * drm_gpuvm_bo_extobj_add() - adds the &drm_gpuvm_bo to its
&drm_gpuvm's
>>> + * extobj list
>>> + * @vm_bo: The &drm_gpuvm_bo to add to its
&drm_gpuvm's the extobj list.
>>> + *
>>> + * Adds the given @vm_bo to its &drm_gpuvm's extobj list
if not on the list
>>> + * already and if the corresponding &drm_gem_object is an
external object,
>>> + * actually.
>>> + */
>>> +void
>>> +drm_gpuvm_bo_extobj_add(struct drm_gpuvm_bo *vm_bo)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>>> +
>>> +??? if (!lock)
>>> +??????? drm_gpuvm_resv_assert_held(gpuvm);
>>> +
>>> +??? if (drm_gpuvm_is_extobj(gpuvm, vm_bo->obj))
>>> +??????? drm_gpuvm_bo_list_add(vm_bo, extobj, lock);
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_extobj_add);
>>> +
>>> +/**
>>> + * drm_gpuvm_bo_evict() - add / remove a &drm_gpuvm_bo to /
from the &drm_gpuvms
>>> + * evicted list
>>> + * @vm_bo: the &drm_gpuvm_bo to add or remove
>>> + * @evict: indicates whether the object is evicted
>>> + *
>>> + * Adds a &drm_gpuvm_bo to or removes it from the
&drm_gpuvms evicted list.
>>> + */
>>> +void
>>> +drm_gpuvm_bo_evict(struct drm_gpuvm_bo *vm_bo, bool evict)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>>> +??? struct drm_gem_object *obj = vm_bo->obj;
>>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>>> +
>>> +??? dma_resv_assert_held(obj->resv);
>>> +
>>> +??? if (drm_gpuvm_is_extobj(gpuvm, obj)) {
>>> +??????? vm_bo->evicted = evict;
>> Does the lock case also need this?
> 
> It doesn't need it by itself, but since we have drm_gpuvm_bo::evicted
now, I want it to
> consistently indicate whether the BO is evicted or not.
> 
>>> +
>>> +??????? if (!lock)
>>> +??????????? return;
>>
>> Here the !lock case can not remove the gpuvm_bo from the list?
> 
> You mean because we'd expect that drm_gpuvm_bo_evict(vm_bo, false) can
only be called from
> within gpuvm_validate(), which requires the VM's resv lock? What if
there is a ttm_validate()
> call for only this GEM obj?
> 
> My idea was to remove VM_BOs from the evicted list in gpuvm_validate()
directly, but I'm afraid
> I forgot that.
Fixed in [1].

[1] https://gitlab.freedesktop.org/nouvelles/kernel/-/tree/gpuvm-next-fixes
> 
>>
>> Small patch here that I've been using for xe:
>>
>> https://patchwork.freedesktop.org/patch/561545/?series=124817&rev=1
>>
>> Thanks,
>>
>> Thomas
>>
>>

On 10/9/23 16:45, Danilo Krummrich wrote:
> On 10/9/23 15:36, Thomas Hellstr?m wrote:
>>
>> On 10/9/23 01:32, 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 at intel.com>
>>> Signed-off-by: Danilo Krummrich <dakr at redhat.com>
>>> ---
>>> ? drivers/gpu/drm/drm_gpuvm.c | 646 
>>> ++++++++++++++++++++++++++++++++++++
>>> ? include/drm/drm_gpuvm.h???? | 246 ++++++++++++++
>>> ? 2 files changed, 892 insertions(+)
>>>
>>> diff --git a/drivers/gpu/drm/drm_gpuvm.c
b/drivers/gpu/drm/drm_gpuvm.c
>>> index 28282283ddaf..6977bd30eca5 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
>>> + * list 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 +670,195 @@
>>> ?? *??? }
>>> ?? */
>>> +/**
>>> + * get_next_vm_bo_from_list() - get the next vm_bo element
>>> + * @__gpuvm: The GPU VM
>>> + * @__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 
>>> drm_gpuvm_get_next_cached_vm_bo()
>>> + *
>>> + * 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??????????????????????????????????? \
>>> +??????????? WARN_ON((__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
>>> + *
>>> + * 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;
>>> + *??? }
>>> + *??? 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 GPU VM
>>> + * @__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)
>>> @@ -760,6 +978,12 @@ drm_gpuvm_init(struct drm_gpuvm *gpuvm, struct
>>> drm_gem_object *r_obj,
>>> ????? 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);
>>> +
>>> ????? drm_gpuvm_check_overflow(start_offset, range);
>>> ????? gpuvm->mm_start = start_offset;
>>> ????? gpuvm->mm_range = range;
>>> @@ -802,10 +1026,372 @@ drm_gpuvm_destroy(struct drm_gpuvm *gpuvm)
>>> ????? WARN(!RB_EMPTY_ROOT(&gpuvm->rb.tree.rb_root),
>>> ?????????? "GPUVA tree is not empty, potentially leaking
memory.\n");
>>> +??? WARN(!list_empty(&gpuvm->extobj.list), "Extobj
list should be
>>> empty.\n");
>>> +??? WARN(!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);
>>
>> Clear vm_bo->evicted here?
>
> Why? It's still evicted, hence why not indicate it? It could be useful 
> for a
> validate_range() use case.
I guess that boils down to what vm_bo->evicted is supposed to mean. I 
have been using it as "This bo needs to be put on the evicted list",
but
if we instead mean "This bo was once evicted and might need revalidation 
and needs rebinding to this VM" then it's OK not to clear it, I guess. 
But note that another VM might have already re-validated the gem BO, and 
also if the locking loop or validate loop restarts due to -EINTR or 
-EDEADLK, then the drm_gpuvm_bo_list_add() will be called multiple 
times, which is OK but unnecessary. So I'd vote for "This bo needs to
be
put on the eviced list".
>
>>
>>
>>> +??? }
>>> +
>>> +??? 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.
>>> + */
>>> +int
>>> +drm_gpuvm_prepare_objects(struct drm_gpuvm *gpuvm,
>>> +????????????? struct drm_exec *exec,
>>> +????????????? unsigned int num_fences)
>>> +{
>>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>>> +??????? return drm_gpuvm_prepare_objects_locked(gpuvm, exec,
>>> +??????????????????????????? num_fences);
>>> +??? else
>>> +??????? return __drm_gpuvm_prepare_objects(gpuvm, exec,
num_fences);
>>> +
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_objects);
>>> +
>>> +/**
>>> + * drm_gpuvm_prepare_range() - prepare all BOs mapped within a 
>>> given range
>>> + * @gpuvm: the &drm_gpuvm
>>> + * @exec: the &drm_exec locking context
>>> + * @addr: the start address within the VA space
>>> + * @range: the range to iterate within the VA space
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + *
>>> + * Calls drm_exec_prepare_obj() for all &drm_gem_objects
mapped
>>> between @addr
>>> + * and @addr + @range.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_prepare_range(struct drm_gpuvm *gpuvm, struct drm_exec 
>>> *exec,
>>> +??????????? u64 addr, u64 range, unsigned int num_fences)
>>> +{
>>> +??? struct drm_gpuva *va;
>>> +??? u64 end = addr + range;
>>> +??? int ret;
>>> +
>>> +??? drm_gpuvm_for_each_va_range(va, gpuvm, addr, end) {
>>> +??????? struct drm_gem_object *obj = va->gem.obj;
>>> +
>>> +??????? ret = drm_exec_prepare_obj(exec, obj, num_fences);
>>> +??????? if (ret)
>>> +??????????? return ret;
>>> +??? }
>>> +
>>> +??? return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_prepare_range);
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock() - lock all dma-resv of all assoiciated
BOs
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects the
given
>>> + * &drm_gpuvm contains mappings of.
>>> + *
>>> + * Addionally, when calling this function with struct 
>>> drm_gpuvm_exec::extra
>>> + * being set the driver receives the given @fn callback to lock 
>>> additional
>>> + * dma-resv in the context of the &drm_gpuvm_exec instance. 
>>> Typically, drivers
>>> + * would call drm_exec_prepare_obj() from within this callback.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock(struct drm_gpuvm_exec *vm_exec,
>>> +??????????? unsigned int num_fences,
>>> +??????????? bool interruptible)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>>> +??? struct drm_exec *exec = &vm_exec->exec;
>>> +??? uint32_t flags;
>>> +??? int ret;
>>> +
>>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>>> +
>>> +??? drm_exec_init(exec, flags);
>>> +
>>> +??? drm_exec_until_all_locked(exec) {
>>> +??????? ret = drm_gpuvm_prepare_vm(gpuvm, exec, num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +
>>> +??????? ret = drm_gpuvm_prepare_objects(gpuvm, exec, num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +
>>> +??????? if (vm_exec->extra.fn) {
>>> +??????????? ret = vm_exec->extra.fn(vm_exec, num_fences);
>>> +??????????? drm_exec_retry_on_contention(exec);
>>> +??????????? if (ret)
>>> +??????????????? goto err;
>>> +??????? }
>>> +??? }
>>> +
>>> +??? return 0;
>>> +
>>> +err:
>>> +??? drm_exec_fini(exec);
>>> +??? return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock);
>>> +
>>> +static int
>>> +fn_lock_array(struct drm_gpuvm_exec *vm_exec, unsigned int
num_fences)
>>> +{
>>> +??? struct {
>>> +??????? struct drm_gem_object **objs;
>>> +??????? unsigned int num_objs;
>>> +??? } *args = vm_exec->extra.priv;
>>> +
>>> +??? return drm_exec_prepare_array(&vm_exec->exec,
args->objs,
>>> +????????????????????? args->num_objs, num_fences);
>>> +}
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock_array() - lock all dma-resv of all 
>>> assoiciated BOs
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @objs: additional &drm_gem_objects to lock
>>> + * @num_objs: the number of additional &drm_gem_objects to
lock
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects the
given
>>> &drm_gpuvm
>>> + * contains mappings of, plus the ones given through @objs.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock_array(struct drm_gpuvm_exec *vm_exec,
>>> +????????????? struct drm_gem_object **objs,
>>> +????????????? unsigned int num_objs,
>>> +????????????? unsigned int num_fences,
>>> +????????????? bool interruptible)
>>> +{
>>> +??? struct {
>>> +??????? struct drm_gem_object **objs;
>>> +??????? unsigned int num_objs;
>>> +??? } args;
>>> +
>>> +??? args.objs = objs;
>>> +??? args.num_objs = num_objs;
>>> +
>>> +??? vm_exec->extra.fn = fn_lock_array;
>>> +??? vm_exec->extra.priv = &args;
>>> +
>>> +??? return drm_gpuvm_exec_lock(vm_exec, num_fences,
interruptible);
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_array);
>>> +
>>> +/**
>>> + * drm_gpuvm_exec_lock_range() - prepare all BOs mapped within a 
>>> given range
>>> + * @vm_exec: the &drm_gpuvm_exec wrapper
>>> + * @addr: the start address within the VA space
>>> + * @range: the range to iterate within the VA space
>>> + * @num_fences: the amount of &dma_fences to reserve
>>> + * @interruptible: sleep interruptible if waiting
>>> + *
>>> + * Acquires all dma-resv locks of all &drm_gem_objects mapped 
>>> between @addr and
>>> + * @addr + @range.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_exec_lock_range(struct drm_gpuvm_exec *vm_exec,
>>> +????????????? u64 addr, u64 range,
>>> +????????????? unsigned int num_fences,
>>> +????????????? bool interruptible)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_exec->vm;
>>> +??? struct drm_exec *exec = &vm_exec->exec;
>>> +??? uint32_t flags;
>>> +??? int ret;
>>> +
>>> +??? flags = interruptible ? DRM_EXEC_INTERRUPTIBLE_WAIT : 0 |
>>> +??????? DRM_EXEC_IGNORE_DUPLICATES;
>>> +
>>> +??? drm_exec_init(exec, flags);
>>> +
>>> +??? drm_exec_until_all_locked(exec) {
>>> +??????? ret = drm_gpuvm_prepare_range(gpuvm, exec, addr, range,
>>> +????????????????????????? num_fences);
>>> +??????? drm_exec_retry_on_contention(exec);
>>> +??????? if (ret)
>>> +??????????? goto err;
>>> +??? }
>>> +
>>> +??? return ret;
>>> +
>>> +err:
>>> +??? drm_exec_fini(exec);
>>> +??? return ret;
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_exec_lock_range);
>>> +
>>> +static int
>>> +__drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec
*exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +??? struct drm_gpuvm_bo *vm_bo;
>>> +??? LIST_HEAD(evict);
>>> +??? int ret = 0;
>>> +
>>> +??? for_each_vm_bo_in_list(gpuvm, evict, &evict, vm_bo) {
>>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>>> +??????? if (ret)
>>> +??????????? break;
>>> +??? }
>>> +??? /* Drop ref in case we break out of the loop. */
>>> +??? drm_gpuvm_bo_put(vm_bo);
>>> +??? restore_vm_bo_list(gpuvm, evict);
>>> +
>>> +??? return ret;
>>> +}
>>> +
>>> +static int
>>> +drm_gpuvm_validate_locked(struct drm_gpuvm *gpuvm, struct drm_exec
>>> *exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +??? struct drm_gpuvm_bo *vm_bo, *next;
>>> +??? int ret = 0;
>>> +
>>> +??? drm_gpuvm_resv_assert_held(gpuvm);
>>> +
>>> +??? /* Iterate list safely, drivers typically remove the current 
>>> entry from
>>> +???? * their drm_gpuvm_ops::vm_bo_validate callback. Drivers might
>>> also
>>> +???? * re-add the entry on failure; this is safe since on failure 
>>> we break
>>> +???? * out of the loop.
>>> +???? */
>>> +??? list_for_each_entry_safe(vm_bo, next,
&gpuvm->evict.list,
>>> +???????????????? list.entry.evict) {
>>> +??????? ret = ops->vm_bo_validate(vm_bo, exec);
>>> +??????? if (ret)
>>> +??????????? break;
>>> +??? }
>>> +
>>> +??? return ret;
>>> +}
>>> +
>>> +/**
>>> + * drm_gpuvm_validate() - validate all BOs marked as evicted
>>> + * @gpuvm: the &drm_gpuvm to validate evicted BOs
>>> + * @exec: the &drm_exec instance used for locking the GPUVM
>>> + *
>>> + * Calls the &drm_gpuvm_ops::vm_bo_validate callback for all 
>>> evicted buffer
>>> + * objects being mapped in the given &drm_gpuvm.
>>> + *
>>> + * Returns: 0 on success, negative error code on failure.
>>> + */
>>> +int
>>> +drm_gpuvm_validate(struct drm_gpuvm *gpuvm, struct drm_exec *exec)
>>> +{
>>> +??? const struct drm_gpuvm_ops *ops = gpuvm->ops;
>>> +
>>> +??? if (unlikely(!ops || !ops->vm_bo_validate))
>>> +??????? return -ENOTSUPP;
>>> +
>>> +??? if (drm_gpuvm_resv_protected(gpuvm))
>>> +??????? return drm_gpuvm_validate_locked(gpuvm, exec);
>>> +??? else
>>> +??????? return __drm_gpuvm_validate(gpuvm, exec);
>>> +
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_validate);
>>> +
>>> +/**
>>> + * drm_gpuvm_resv_add_fence - add fence to private and all extobj
>>> + * dma-resv
>>> + * @gpuvm: the &drm_gpuvm to add a fence to
>>> + * @exec: the &drm_exec locking context
>>> + * @fence: fence to add
>>> + * @private_usage: private dma-resv usage
>>> + * @extobj_usage: extobj dma-resv usage
>>> + */
>>> +void
>>> +drm_gpuvm_resv_add_fence(struct drm_gpuvm *gpuvm,
>>> +???????????? struct drm_exec *exec,
>>> +???????????? struct dma_fence *fence,
>>> +???????????? enum dma_resv_usage private_usage,
>>> +???????????? enum dma_resv_usage extobj_usage)
>>> +{
>>> +??? struct drm_gem_object *obj;
>>> +??? unsigned long index;
>>> +
>>> +??? drm_exec_for_each_locked_object(exec, index, obj) {
>>> +??????? dma_resv_assert_held(obj->resv);
>>> +??????? dma_resv_add_fence(obj->resv, fence,
>>> +?????????????????? drm_gpuvm_is_extobj(gpuvm, obj) ?
>>> +?????????????????? private_usage : extobj_usage);
>>> +??? }
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_resv_add_fence);
>>> +
>>> ? /**
>>> ?? * drm_gpuvm_bo_create() - create a new instance of struct 
>>> drm_gpuvm_bo
>>> ?? * @gpuvm: The &drm_gpuvm the @obj is mapped in.
>>> @@ -838,6 +1424,9 @@ drm_gpuvm_bo_create(struct drm_gpuvm *gpuvm,
>>> ????? INIT_LIST_HEAD(&vm_bo->list.gpuva);
>>> ????? INIT_LIST_HEAD(&vm_bo->list.entry.gem);
>>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.extobj);
>>> +??? INIT_LIST_HEAD(&vm_bo->list.entry.evict);
>>> +
>>> ????? drm_gem_object_get(obj);
>>> ????? return vm_bo;
>>> @@ -858,6 +1447,9 @@ drm_gpuvm_bo_destroy(struct kref *kref)
>>> ????? if (!lock)
>>> ????????? drm_gpuvm_resv_assert_held(gpuvm);
>>> +??? drm_gpuvm_bo_list_del(vm_bo, extobj, lock);
>>> +??? drm_gpuvm_bo_list_del(vm_bo, evict, lock);
>>> +
>>> ????? list_del(&vm_bo->list.entry.gem);
>>> ????? drm_gem_object_put(obj);
>>> @@ -994,6 +1586,60 @@ drm_gpuvm_bo_obtain_prealloc(struct 
>>> drm_gpuvm_bo *__vm_bo)
>>> ? }
>>> ? EXPORT_SYMBOL_GPL(drm_gpuvm_bo_obtain_prealloc);
>>> +/**
>>> + * drm_gpuvm_bo_extobj_add() - adds the &drm_gpuvm_bo to its 
>>> &drm_gpuvm's
>>> + * extobj list
>>> + * @vm_bo: The &drm_gpuvm_bo to add to its
&drm_gpuvm's the extobj
>>> list.
>>> + *
>>> + * Adds the given @vm_bo to its &drm_gpuvm's extobj list
if not on
>>> the list
>>> + * already and if the corresponding &drm_gem_object is an
external
>>> object,
>>> + * actually.
>>> + */
>>> +void
>>> +drm_gpuvm_bo_extobj_add(struct drm_gpuvm_bo *vm_bo)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>>> +
>>> +??? if (!lock)
>>> +??????? drm_gpuvm_resv_assert_held(gpuvm);
>>> +
>>> +??? if (drm_gpuvm_is_extobj(gpuvm, vm_bo->obj))
>>> +??????? drm_gpuvm_bo_list_add(vm_bo, extobj, lock);
>>> +}
>>> +EXPORT_SYMBOL_GPL(drm_gpuvm_bo_extobj_add);
>>> +
>>> +/**
>>> + * drm_gpuvm_bo_evict() - add / remove a &drm_gpuvm_bo to /
from
>>> the &drm_gpuvms
>>> + * evicted list
>>> + * @vm_bo: the &drm_gpuvm_bo to add or remove
>>> + * @evict: indicates whether the object is evicted
>>> + *
>>> + * Adds a &drm_gpuvm_bo to or removes it from the
&drm_gpuvms
>>> evicted list.
>>> + */
>>> +void
>>> +drm_gpuvm_bo_evict(struct drm_gpuvm_bo *vm_bo, bool evict)
>>> +{
>>> +??? struct drm_gpuvm *gpuvm = vm_bo->vm;
>>> +??? struct drm_gem_object *obj = vm_bo->obj;
>>> +??? bool lock = !drm_gpuvm_resv_protected(gpuvm);
>>> +
>>> +??? dma_resv_assert_held(obj->resv);
>>> +
>>> +??? if (drm_gpuvm_is_extobj(gpuvm, obj)) {
>>> +??????? vm_bo->evicted = evict;
>> Does the lock case also need this?
>
> It doesn't need it by itself, but since we have drm_gpuvm_bo::evicted 
> now, I want it to
> consistently indicate whether the BO is evicted or not.
OK, I guess that ties to the meaning of bo->evicted, as discussed above.
>
>>> +
>>> +??????? if (!lock)
>>> +??????????? return;
>>
>> Here the !lock case can not remove the gpuvm_bo from the list?
>
> You mean because we'd expect that drm_gpuvm_bo_evict(vm_bo, false) can 
> only be called from
> within gpuvm_validate(), which requires the VM's resv lock? What if 
> there is a ttm_validate()
> call for only this GEM obj?
>
> My idea was to remove VM_BOs from the evicted list in gpuvm_validate() 
> directly, but I'm afraid
> I forgot that.
Yes, I think the helper could do it if validate() is successful. But 
what I meant above was that if the *driver* is responsible for removing 
object from the evicted list, then if it's a RESV_PROTECTED vm, it can't
do that because drm_gpuvm_bo_evict(gpuvm, false) will never get to 
removing it from the list because it returns early.

Thanks,

Thomas

>
>>
>> Small patch here that I've been using for xe:
>>
>> https://patchwork.freedesktop.org/patch/561545/?series=124817&rev=1
>>
>> Thanks,
>>
>> Thomas
>>
>>
>