Re: [PATCH 4/8] drm/ttm: factor out ttm_bo_mmap_vma_setup

From: Thomas Zimmermann
Date: Fri Sep 13 2019 - 08:56:19 EST


Hi

Am 13.09.19 um 14:29 schrieb Gerd Hoffmann:
> Factor out ttm vma setup to a new function. Reduces
> code duplication a bit and allows to implement
> &drm_gem_object_funcs.mmap in gem ttm helpers.
>
> Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> ---
> include/drm/ttm/ttm_bo_api.h | 8 ++++++
> drivers/gpu/drm/ttm/ttm_bo_vm.c | 47 ++++++++++++++++++---------------
> 2 files changed, 33 insertions(+), 22 deletions(-)
>
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 43c4929a2171..88c652f49602 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -734,6 +734,14 @@ int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo);
> int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
> struct ttm_bo_device *bdev);
>
> +/**
> + * ttm_bo_mmap_vma_setup - initialize vma for ttm bo mmap
> + *
> + * @bo: The buffer object.
> + * @vma: vma as input from the mmap method.
> + */
> +void ttm_bo_mmap_vma_setup(struct ttm_buffer_object *bo, struct vm_area_struct *vma);
> +
> void *ttm_kmap_atomic_prot(struct page *page, pgprot_t prot);
>
> void ttm_kunmap_atomic_prot(void *addr, pgprot_t prot);
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index 4aa007edffb0..7c0e85c10e0e 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -426,6 +426,29 @@ static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
> return bo;
> }
>
> +void ttm_bo_mmap_vma_setup(struct ttm_buffer_object *bo, struct vm_area_struct *vma)
> +{
> + vma->vm_ops = &ttm_bo_vm_ops;
> +
> + /*
> + * Note: We're transferring the bo reference to
> + * vma->vm_private_data here.
> + */
> +
> + vma->vm_private_data = bo;
> +
> + /*
> + * We'd like to use VM_PFNMAP on shared mappings, where
> + * (vma->vm_flags & VM_SHARED) != 0, for performance reasons,
> + * but for some reason VM_PFNMAP + x86 PAT + write-combine is very
> + * bad for performance. Until that has been sorted out, use
> + * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
> + */
> + vma->vm_flags |= VM_MIXEDMAP;
> + vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
> +}
> +EXPORT_SYMBOL(ttm_bo_mmap_vma_setup);
> +
> int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
> struct ttm_bo_device *bdev)
> {
> @@ -449,24 +472,7 @@ int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
> if (unlikely(ret != 0))
> goto out_unref;
>
> - vma->vm_ops = &ttm_bo_vm_ops;
> -
> - /*
> - * Note: We're transferring the bo reference to
> - * vma->vm_private_data here.
> - */
> -
> - vma->vm_private_data = bo;
> -
> - /*
> - * We'd like to use VM_PFNMAP on shared mappings, where
> - * (vma->vm_flags & VM_SHARED) != 0, for performance reasons,
> - * but for some reason VM_PFNMAP + x86 PAT + write-combine is very
> - * bad for performance. Until that has been sorted out, use
> - * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
> - */
> - vma->vm_flags |= VM_MIXEDMAP;
> - vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
> + ttm_bo_mmap_vma_setup(bo, vma);
> return 0;
> out_unref:
> ttm_bo_put(bo);
> @@ -481,10 +487,7 @@ int ttm_fbdev_mmap(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
>
> ttm_bo_get(bo);
>
> - vma->vm_ops = &ttm_bo_vm_ops;
> - vma->vm_private_data = bo;
> - vma->vm_flags |= VM_MIXEDMAP;
> - vma->vm_flags |= VM_IO | VM_DONTEXPAND;
> + ttm_bo_mmap_vma_setup(bo, vma);
Just double-checking: ttm_bo_mmap_vma_setup() will set VM_DONTDUMP in
vm_flags. Is that OK?

Best regards
Thomas

> return 0;
> }
> EXPORT_SYMBOL(ttm_fbdev_mmap);
>

--
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix ImendÃrffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG NÃrnberg)

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