Re: [PATCH v3] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Boris Brezillon <boris.brezillon@collabora.com>]

On Wed, 30 Oct 2024 16:02:31 +0100
Boris Brezillon <boris.brezillon@collabora.com> wrote:

> The system and GPU MMU page size might differ, which becomes a
> problem for FW sections that need to be mapped at explicit addresses
> since our PAGE_SIZE alignment might cover a VA range that's
> expected to be used for another section.
> 
> Make sure we never map more than we need.
> 
> Changes in v3:
> - Add R-bs
> 
> Changes in v2:
> - Plan for per-VM page sizes so the MCU VM and user VM can
>   have different pages sizes
> 
> Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> Reviewed-by: Steven Price <steven.price@arm.com>
> Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Queued to drm-misc-fixes.

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c  |  4 ++--
>  drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 16 +++++++++++++---
>  drivers/gpu/drm/panthor/panthor_mmu.h |  1 +
>  4 files changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index 631f639b8b86..ecca5565ce41 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -500,6 +500,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
>  					 struct panthor_fw_binary_iter *iter,
>  					 u32 ehdr)
>  {
> +	ssize_t vm_pgsz = panthor_vm_page_size(ptdev->fw->vm);
>  	struct panthor_fw_binary_section_entry_hdr hdr;
>  	struct panthor_fw_section *section;
>  	u32 section_size;
> @@ -528,8 +529,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
>  		return -EINVAL;
>  	}
>  
> -	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
> -	    (hdr.va.end & ~PAGE_MASK) != 0) {
> +	if (!IS_ALIGNED(hdr.va.start, vm_pgsz) || !IS_ALIGNED(hdr.va.end, vm_pgsz)) {
>  		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
>  			hdr.va.start, hdr.va.end);
>  		return -EINVAL;
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index c60b599665d8..8244a4e6c2a2 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
>  			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
>  		goto out_free_bo;
>  
> -	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
> -				     panthor_kernel_bo_size(bo));
> +	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
>  	if (ret)
>  		goto out_free_bo;
>  
> @@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
>  	}
>  
>  	bo = to_panthor_bo(&obj->base);
> -	size = obj->base.size;
>  	kbo->obj = &obj->base;
>  	bo->flags = bo_flags;
>  
> +	/* The system and GPU MMU page size might differ, which becomes a
> +	 * problem for FW sections that need to be mapped at explicit address
> +	 * since our PAGE_SIZE alignment might cover a VA range that's
> +	 * expected to be used for another section.
> +	 * Make sure we never map more than we need.
> +	 */
> +	size = ALIGN(size, panthor_vm_page_size(vm));
>  	ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
>  	if (ret)
>  		goto err_put_obj;
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index aa12ed2acfcf..8ca85526491e 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -826,6 +826,14 @@ void panthor_vm_idle(struct panthor_vm *vm)
>  	mutex_unlock(&ptdev->mmu->as.slots_lock);
>  }
>  
> +u32 panthor_vm_page_size(struct panthor_vm *vm)
> +{
> +	const struct io_pgtable *pgt = io_pgtable_ops_to_pgtable(vm->pgtbl_ops);
> +	u32 pg_shift = ffs(pgt->cfg.pgsize_bitmap) - 1;
> +
> +	return 1u << pg_shift;
> +}
> +
>  static void panthor_vm_stop(struct panthor_vm *vm)
>  {
>  	drm_sched_stop(&vm->sched, NULL);
> @@ -1025,12 +1033,13 @@ int
>  panthor_vm_alloc_va(struct panthor_vm *vm, u64 va, u64 size,
>  		    struct drm_mm_node *va_node)
>  {
> +	ssize_t vm_pgsz = panthor_vm_page_size(vm);
>  	int ret;
>  
> -	if (!size || (size & ~PAGE_MASK))
> +	if (!size || !IS_ALIGNED(size, vm_pgsz))
>  		return -EINVAL;
>  
> -	if (va != PANTHOR_VM_KERNEL_AUTO_VA && (va & ~PAGE_MASK))
> +	if (va != PANTHOR_VM_KERNEL_AUTO_VA && !IS_ALIGNED(va, vm_pgsz))
>  		return -EINVAL;
>  
>  	mutex_lock(&vm->mm_lock);
> @@ -2366,11 +2375,12 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
>  			       const struct drm_panthor_vm_bind_op *op,
>  			       struct panthor_vm_op_ctx *op_ctx)
>  {
> +	ssize_t vm_pgsz = panthor_vm_page_size(vm);
>  	struct drm_gem_object *gem;
>  	int ret;
>  
>  	/* Aligned on page size. */
> -	if ((op->va | op->size) & ~PAGE_MASK)
> +	if (!IS_ALIGNED(op->va | op->size, vm_pgsz))
>  		return -EINVAL;
>  
>  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.h b/drivers/gpu/drm/panthor/panthor_mmu.h
> index 6788771071e3..8d21e83d8aba 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.h
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.h
> @@ -30,6 +30,7 @@ panthor_vm_get_bo_for_va(struct panthor_vm *vm, u64 va, u64 *bo_offset);
>  
>  int panthor_vm_active(struct panthor_vm *vm);
>  void panthor_vm_idle(struct panthor_vm *vm);
> +u32 panthor_vm_page_size(struct panthor_vm *vm);
>  int panthor_vm_as(struct panthor_vm *vm);
>  int panthor_vm_flush_all(struct panthor_vm *vm);
>