Avoids use-after-free situations when panthor_fw_unplug() is called
and the kernel BO was mapped to the FW VM.

Signed-off-by: Boris Brezillon <boris.brezil...@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_fw.c    |  4 ++--
 drivers/gpu/drm/panthor/panthor_gem.c   |  8 +++++---
 drivers/gpu/drm/panthor/panthor_gem.h   |  8 ++++++--
 drivers/gpu/drm/panthor/panthor_heap.c  |  8 ++++----
 drivers/gpu/drm/panthor/panthor_sched.c | 11 +++++------
 5 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c 
b/drivers/gpu/drm/panthor/panthor_fw.c
index 181395e2859a..b41685304a83 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -453,7 +453,7 @@ panthor_fw_alloc_queue_iface_mem(struct panthor_device 
*ptdev,
 
        ret = panthor_kernel_bo_vmap(mem);
        if (ret) {
-               panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), mem);
+               panthor_kernel_bo_destroy(mem);
                return ERR_PTR(ret);
        }
 
@@ -1133,7 +1133,7 @@ void panthor_fw_unplug(struct panthor_device *ptdev)
        panthor_fw_stop(ptdev);
 
        list_for_each_entry(section, &ptdev->fw->sections, node)
-               panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), section->mem);
+               panthor_kernel_bo_destroy(section->mem);
 
        /* We intentionally don't call panthor_vm_idle() and let
         * panthor_mmu_unplug() release the AS we acquired with
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c 
b/drivers/gpu/drm/panthor/panthor_gem.c
index d6483266d0c2..38f560864879 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -26,18 +26,18 @@ static void panthor_gem_free_object(struct drm_gem_object 
*obj)
 
 /**
  * panthor_kernel_bo_destroy() - Destroy a kernel buffer object
- * @vm: The VM this BO was mapped to.
  * @bo: Kernel buffer object to destroy. If NULL or an ERR_PTR(), the 
destruction
  * is skipped.
  */
-void panthor_kernel_bo_destroy(struct panthor_vm *vm,
-                              struct panthor_kernel_bo *bo)
+void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
 {
+       struct panthor_vm *vm;
        int ret;
 
        if (IS_ERR_OR_NULL(bo))
                return;
 
+       vm = bo->vm;
        panthor_kernel_bo_vunmap(bo);
 
        if (drm_WARN_ON(bo->obj->dev,
@@ -53,6 +53,7 @@ void panthor_kernel_bo_destroy(struct panthor_vm *vm,
        drm_gem_object_put(bo->obj);
 
 out_free_bo:
+       panthor_vm_put(vm);
        kfree(bo);
 }
 
@@ -106,6 +107,7 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, 
struct panthor_vm *vm,
        if (ret)
                goto err_free_va;
 
+       kbo->vm = panthor_vm_get(vm);
        bo->exclusive_vm_root_gem = panthor_vm_root_gem(vm);
        drm_gem_object_get(bo->exclusive_vm_root_gem);
        bo->base.base.resv = bo->exclusive_vm_root_gem->resv;
diff --git a/drivers/gpu/drm/panthor/panthor_gem.h 
b/drivers/gpu/drm/panthor/panthor_gem.h
index 3bccba394d00..e43021cf6d45 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.h
+++ b/drivers/gpu/drm/panthor/panthor_gem.h
@@ -61,6 +61,11 @@ struct panthor_kernel_bo {
         */
        struct drm_gem_object *obj;
 
+       /**
+        * @vm: VM this private buffer is attached to.
+        */
+       struct panthor_vm *vm;
+
        /**
         * @va_node: VA space allocated to this GEM.
         */
@@ -136,7 +141,6 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, 
struct panthor_vm *vm,
                         size_t size, u32 bo_flags, u32 vm_map_flags,
                         u64 gpu_va);
 
-void panthor_kernel_bo_destroy(struct panthor_vm *vm,
-                              struct panthor_kernel_bo *bo);
+void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo);
 
 #endif /* __PANTHOR_GEM_H__ */
diff --git a/drivers/gpu/drm/panthor/panthor_heap.c 
b/drivers/gpu/drm/panthor/panthor_heap.c
index 143fa35f2e74..65921296a18c 100644
--- a/drivers/gpu/drm/panthor/panthor_heap.c
+++ b/drivers/gpu/drm/panthor/panthor_heap.c
@@ -127,7 +127,7 @@ static void panthor_free_heap_chunk(struct panthor_vm *vm,
        heap->chunk_count--;
        mutex_unlock(&heap->lock);
 
-       panthor_kernel_bo_destroy(vm, chunk->bo);
+       panthor_kernel_bo_destroy(chunk->bo);
        kfree(chunk);
 }
 
@@ -183,7 +183,7 @@ static int panthor_alloc_heap_chunk(struct panthor_device 
*ptdev,
        return 0;
 
 err_destroy_bo:
-       panthor_kernel_bo_destroy(vm, chunk->bo);
+       panthor_kernel_bo_destroy(chunk->bo);
 
 err_free_chunk:
        kfree(chunk);
@@ -391,7 +391,7 @@ int panthor_heap_return_chunk(struct panthor_heap_pool 
*pool,
        mutex_unlock(&heap->lock);
 
        if (removed) {
-               panthor_kernel_bo_destroy(pool->vm, chunk->bo);
+               panthor_kernel_bo_destroy(chunk->bo);
                kfree(chunk);
                ret = 0;
        } else {
@@ -587,7 +587,7 @@ void panthor_heap_pool_destroy(struct panthor_heap_pool 
*pool)
                drm_WARN_ON(&pool->ptdev->base, 
panthor_heap_destroy_locked(pool, i));
 
        if (!IS_ERR_OR_NULL(pool->gpu_contexts))
-               panthor_kernel_bo_destroy(pool->vm, pool->gpu_contexts);
+               panthor_kernel_bo_destroy(pool->gpu_contexts);
 
        /* Reflects the fact the pool has been destroyed. */
        pool->vm = NULL;
diff --git a/drivers/gpu/drm/panthor/panthor_sched.c 
b/drivers/gpu/drm/panthor/panthor_sched.c
index 1d2708c3ab0a..6ea094b00cf9 100644
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -826,8 +826,8 @@ static void group_free_queue(struct panthor_group *group, 
struct panthor_queue *
 
        panthor_queue_put_syncwait_obj(queue);
 
-       panthor_kernel_bo_destroy(group->vm, queue->ringbuf);
-       panthor_kernel_bo_destroy(panthor_fw_vm(group->ptdev), 
queue->iface.mem);
+       panthor_kernel_bo_destroy(queue->ringbuf);
+       panthor_kernel_bo_destroy(queue->iface.mem);
 
        kfree(queue);
 }
@@ -837,15 +837,14 @@ static void group_release_work(struct work_struct *work)
        struct panthor_group *group = container_of(work,
                                                   struct panthor_group,
                                                   release_work);
-       struct panthor_device *ptdev = group->ptdev;
        u32 i;
 
        for (i = 0; i < group->queue_count; i++)
                group_free_queue(group, group->queues[i]);
 
-       panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), group->suspend_buf);
-       panthor_kernel_bo_destroy(panthor_fw_vm(ptdev), 
group->protm_suspend_buf);
-       panthor_kernel_bo_destroy(group->vm, group->syncobjs);
+       panthor_kernel_bo_destroy(group->suspend_buf);
+       panthor_kernel_bo_destroy(group->protm_suspend_buf);
+       panthor_kernel_bo_destroy(group->syncobjs);
 
        panthor_vm_put(group->vm);
        kfree(group);
-- 
2.44.0

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