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panthor: use drm_gpuva_unlink_defer()

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Instead of manually deferring cleanup of vm_bos, use the new GPUVM
infrastructure for doing so.

To avoid manual management of vm_bo refcounts, the panthor_vma_link()
and panthor_vma_unlink() methods are changed to get and put a vm_bo
refcount on the vm_bo. This simplifies the code a lot. I preserved the
behavior where panthor_gpuva_sm_step_map() drops the refcount right away
rather than letting panthor_vm_cleanup_op_ctx() do it later.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/r/20251006-vmbo-defer-v4-2-30cbd2c05adb@google.com
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
This commit is contained in:
Alice Ryhl
2025-10-06 12:05:56 +00:00
parent 8e4865faf7
commit 63e919a316
1 changed files with 19 additions and 91 deletions
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110
drivers/gpu/drm/panthor/panthor_mmu.c
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@@ -181,20 +181,6 @@ struct panthor_vm_op_ctx {
u64 range;
} va;
/**
* @returned_vmas: List of panthor_vma objects returned after a VM operation.
*
* For unmap operations, this will contain all VMAs that were covered by the
* specified VA range.
*
* For map operations, this will contain all VMAs that previously mapped to
* the specified VA range.
*
* Those VMAs, and the resources they point to will be released as part of
* the op_ctx cleanup operation.
*/
struct list_head returned_vmas;
/** @map: Fields specific to a map operation. */
struct {
/** @map.vm_bo: Buffer object to map. */
@@ -1081,47 +1067,18 @@ void panthor_vm_free_va(struct panthor_vm *vm, struct drm_mm_node *va_node)
mutex_unlock(&vm->mm_lock);
}
static void panthor_vm_bo_put(struct drm_gpuvm_bo *vm_bo)
static void panthor_vm_bo_free(struct drm_gpuvm_bo *vm_bo)
{
struct panthor_gem_object *bo = to_panthor_bo(vm_bo->obj);
struct drm_gpuvm *vm = vm_bo->vm;
bool unpin;
/* We must retain the GEM before calling drm_gpuvm_bo_put(),
* otherwise the mutex might be destroyed while we hold it.
* Same goes for the VM, since we take the VM resv lock.
*/
drm_gem_object_get(&bo->base.base);
drm_gpuvm_get(vm);
/* We take the resv lock to protect against concurrent accesses to the
* gpuvm evicted/extobj lists that are modified in
* drm_gpuvm_bo_destroy(), which is called if drm_gpuvm_bo_put()
* releases sthe last vm_bo reference.
* We take the BO GPUVA list lock to protect the vm_bo removal from the
* GEM vm_bo list.
*/
dma_resv_lock(drm_gpuvm_resv(vm), NULL);
mutex_lock(&bo->base.base.gpuva.lock);
unpin = drm_gpuvm_bo_put(vm_bo);
mutex_unlock(&bo->base.base.gpuva.lock);
dma_resv_unlock(drm_gpuvm_resv(vm));
/* If the vm_bo object was destroyed, release the pin reference that
* was hold by this object.
*/
if (unpin && !drm_gem_is_imported(&bo->base.base))
if (!drm_gem_is_imported(&bo->base.base))
drm_gem_shmem_unpin(&bo->base);
drm_gpuvm_put(vm);
drm_gem_object_put(&bo->base.base);
kfree(vm_bo);
}
static void panthor_vm_cleanup_op_ctx(struct panthor_vm_op_ctx *op_ctx,
struct panthor_vm *vm)
{
struct panthor_vma *vma, *tmp_vma;
u32 remaining_pt_count = op_ctx->rsvd_page_tables.count -
op_ctx->rsvd_page_tables.ptr;
@@ -1134,16 +1091,12 @@ static void panthor_vm_cleanup_op_ctx(struct panthor_vm_op_ctx *op_ctx,
kfree(op_ctx->rsvd_page_tables.pages);
if (op_ctx->map.vm_bo)
panthor_vm_bo_put(op_ctx->map.vm_bo);
drm_gpuvm_bo_put_deferred(op_ctx->map.vm_bo);
for (u32 i = 0; i < ARRAY_SIZE(op_ctx->preallocated_vmas); i++)
kfree(op_ctx->preallocated_vmas[i]);
list_for_each_entry_safe(vma, tmp_vma, &op_ctx->returned_vmas, node) {
list_del(&vma->node);
panthor_vm_bo_put(vma->base.vm_bo);
kfree(vma);
}
drm_gpuvm_bo_deferred_cleanup(&vm->base);
}
static struct panthor_vma *
@@ -1232,7 +1185,6 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
return -EINVAL;
memset(op_ctx, 0, sizeof(*op_ctx));
INIT_LIST_HEAD(&op_ctx->returned_vmas);
op_ctx->flags = flags;
op_ctx->va.range = size;
op_ctx->va.addr = va;
@@ -1243,7 +1195,9 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
if (!drm_gem_is_imported(&bo->base.base)) {
/* Pre-reserve the BO pages, so the map operation doesn't have to
* allocate.
* allocate. This pin is dropped in panthor_vm_bo_free(), so
* once we have successfully called drm_gpuvm_bo_create(),
* GPUVM will take care of dropping the pin for us.
*/
ret = drm_gem_shmem_pin(&bo->base);
if (ret)
@@ -1282,16 +1236,6 @@ static int panthor_vm_prepare_map_op_ctx(struct panthor_vm_op_ctx *op_ctx,
mutex_unlock(&bo->base.base.gpuva.lock);
dma_resv_unlock(panthor_vm_resv(vm));
/* If the a vm_bo for this <VM,BO> combination exists, it already
* retains a pin ref, and we can release the one we took earlier.
*
* If our pre-allocated vm_bo is picked, it now retains the pin ref,
* which will be released in panthor_vm_bo_put().
*/
if (preallocated_vm_bo != op_ctx->map.vm_bo &&
!drm_gem_is_imported(&bo->base.base))
drm_gem_shmem_unpin(&bo->base);
op_ctx->map.bo_offset = offset;
/* L1, L2 and L3 page tables.
@@ -1339,7 +1283,6 @@ static int panthor_vm_prepare_unmap_op_ctx(struct panthor_vm_op_ctx *op_ctx,
int ret;
memset(op_ctx, 0, sizeof(*op_ctx));
INIT_LIST_HEAD(&op_ctx->returned_vmas);
op_ctx->va.range = size;
op_ctx->va.addr = va;
op_ctx->flags = DRM_PANTHOR_VM_BIND_OP_TYPE_UNMAP;
@@ -1387,7 +1330,6 @@ static void panthor_vm_prepare_sync_only_op_ctx(struct panthor_vm_op_ctx *op_ctx
struct panthor_vm *vm)
{
memset(op_ctx, 0, sizeof(*op_ctx));
INIT_LIST_HEAD(&op_ctx->returned_vmas);
op_ctx->flags = DRM_PANTHOR_VM_BIND_OP_TYPE_SYNC_ONLY;
}
@@ -2033,26 +1975,13 @@ static void panthor_vma_link(struct panthor_vm *vm,
mutex_lock(&bo->base.base.gpuva.lock);
drm_gpuva_link(&vma->base, vm_bo);
drm_WARN_ON(&vm->ptdev->base, drm_gpuvm_bo_put(vm_bo));
mutex_unlock(&bo->base.base.gpuva.lock);
}
static void panthor_vma_unlink(struct panthor_vm *vm,
struct panthor_vma *vma)
static void panthor_vma_unlink(struct panthor_vma *vma)
{
struct panthor_gem_object *bo = to_panthor_bo(vma->base.gem.obj);
struct drm_gpuvm_bo *vm_bo = drm_gpuvm_bo_get(vma->base.vm_bo);
mutex_lock(&bo->base.base.gpuva.lock);
drm_gpuva_unlink(&vma->base);
mutex_unlock(&bo->base.base.gpuva.lock);
/* drm_gpuva_unlink() release the vm_bo, but we manually retained it
* when entering this function, so we can implement deferred VMA
* destruction. Re-assign it here.
*/
vma->base.vm_bo = vm_bo;
list_add_tail(&vma->node, &vm->op_ctx->returned_vmas);
drm_gpuva_unlink_defer(&vma->base);
kfree(vma);
}
static void panthor_vma_init(struct panthor_vma *vma, u32 flags)
@@ -2084,12 +2013,12 @@ static int panthor_gpuva_sm_step_map(struct drm_gpuva_op *op, void *priv)
if (ret)
return ret;
/* Ref owned by the mapping now, clear the obj field so we don't release the
* pinning/obj ref behind GPUVA's back.
*/
drm_gpuva_map(&vm->base, &vma->base, &op->map);
panthor_vma_link(vm, vma, op_ctx->map.vm_bo);
drm_gpuvm_bo_put_deferred(op_ctx->map.vm_bo);
op_ctx->map.vm_bo = NULL;
return 0;
}
@@ -2128,16 +2057,14 @@ static int panthor_gpuva_sm_step_remap(struct drm_gpuva_op *op,
* owned by the old mapping which will be released when this
* mapping is destroyed, we need to grab a ref here.
*/
panthor_vma_link(vm, prev_vma,
drm_gpuvm_bo_get(op->remap.unmap->va->vm_bo));
panthor_vma_link(vm, prev_vma, op->remap.unmap->va->vm_bo);
}
if (next_vma) {
panthor_vma_link(vm, next_vma,
drm_gpuvm_bo_get(op->remap.unmap->va->vm_bo));
panthor_vma_link(vm, next_vma, op->remap.unmap->va->vm_bo);
}
panthor_vma_unlink(vm, unmap_vma);
panthor_vma_unlink(unmap_vma);
return 0;
}
@@ -2154,12 +2081,13 @@ static int panthor_gpuva_sm_step_unmap(struct drm_gpuva_op *op,
return ret;
drm_gpuva_unmap(&op->unmap);
panthor_vma_unlink(vm, unmap_vma);
panthor_vma_unlink(unmap_vma);
return 0;
}
static const struct drm_gpuvm_ops panthor_gpuvm_ops = {
.vm_free = panthor_vm_free,
.vm_bo_free = panthor_vm_bo_free,
.sm_step_map = panthor_gpuva_sm_step_map,
.sm_step_remap = panthor_gpuva_sm_step_remap,
.sm_step_unmap = panthor_gpuva_sm_step_unmap,