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Re: [PATCH 2/3] drm/xen: Implement mmap as GEM object function



Hi, Thomas!

On 08.11.21 12:28, Thomas Zimmermann wrote:
> Moving the driver-specific mmap code into a GEM object function allows
> for using DRM helpers for various mmap callbacks.
>
> The respective xen functions are being removed. The file_operations
> structure fops is now being created by the helper macro
> DEFINE_DRM_GEM_FOPS().
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> ---
>   drivers/gpu/drm/xen/xen_drm_front.c     |  16 +---
>   drivers/gpu/drm/xen/xen_drm_front_gem.c | 108 +++++++++---------------
>   drivers/gpu/drm/xen/xen_drm_front_gem.h |   7 --
>   3 files changed, 44 insertions(+), 87 deletions(-)
>
> diff --git a/drivers/gpu/drm/xen/xen_drm_front.c 
> b/drivers/gpu/drm/xen/xen_drm_front.c
> index 9f14d99c763c..434064c820e8 100644
> --- a/drivers/gpu/drm/xen/xen_drm_front.c
> +++ b/drivers/gpu/drm/xen/xen_drm_front.c
> @@ -469,19 +469,7 @@ static void xen_drm_drv_release(struct drm_device *dev)
>       kfree(drm_info);
>   }
>   
> -static const struct file_operations xen_drm_dev_fops = {
> -     .owner          = THIS_MODULE,
> -     .open           = drm_open,
> -     .release        = drm_release,
> -     .unlocked_ioctl = drm_ioctl,
> -#ifdef CONFIG_COMPAT
> -     .compat_ioctl   = drm_compat_ioctl,
> -#endif
> -     .poll           = drm_poll,
> -     .read           = drm_read,
> -     .llseek         = no_llseek,
> -     .mmap           = xen_drm_front_gem_mmap,
> -};
> +DEFINE_DRM_GEM_FOPS(xen_drm_dev_fops);
>   
>   static const struct drm_driver xen_drm_driver = {
>       .driver_features           = DRIVER_GEM | DRIVER_MODESET | 
> DRIVER_ATOMIC,
> @@ -489,7 +477,7 @@ static const struct drm_driver xen_drm_driver = {
>       .prime_handle_to_fd        = drm_gem_prime_handle_to_fd,
>       .prime_fd_to_handle        = drm_gem_prime_fd_to_handle,
>       .gem_prime_import_sg_table = xen_drm_front_gem_import_sg_table,
> -     .gem_prime_mmap            = xen_drm_front_gem_prime_mmap,
> +     .gem_prime_mmap            = drm_gem_prime_mmap,
>       .dumb_create               = xen_drm_drv_dumb_create,
>       .fops                      = &xen_drm_dev_fops,
>       .name                      = "xendrm-du",
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.c 
> b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> index b293c67230ef..dd358ba2bf8e 100644
> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.c
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.c
> @@ -57,6 +57,47 @@ static void gem_free_pages_array(struct xen_gem_object 
> *xen_obj)
>       xen_obj->pages = NULL;
>   }
>   
> +static int xen_drm_front_gem_object_mmap(struct drm_gem_object *gem_obj,
> +                                      struct vm_area_struct *vma)
> +{
> +     struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> +     int ret;
> +
> +     vma->vm_ops = gem_obj->funcs->vm_ops;
> +
> +     /*
> +      * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
> +      * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
> +      * the whole buffer.
> +      */
> +     vma->vm_flags &= ~VM_PFNMAP;
> +     vma->vm_flags |= VM_MIXEDMAP;
> +     vma->vm_pgoff = 0;
> +
> +     /*
> +      * According to Xen on ARM ABI (xen/include/public/arch-arm.h):
> +      * all memory which is shared with other entities in the system
> +      * (including the hypervisor and other guests) must reside in memory
> +      * which is mapped as Normal Inner Write-Back Outer Write-Back
> +      * Inner-Shareable.
> +      */
> +     vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> +
> +     /*
> +      * vm_operations_struct.fault handler will be called if CPU access
> +      * to VM is here. For GPUs this isn't the case, because CPU  doesn't
> +      * touch the memory. Insert pages now, so both CPU and GPU are happy.
> +      *
> +      * FIXME: as we insert all the pages now then no .fault handler must
> +      * be called, so don't provide one
> +      */
> +     ret = vm_map_pages(vma, xen_obj->pages, xen_obj->num_pages);
> +     if (ret < 0)
> +             DRM_ERROR("Failed to map pages into vma: %d\n", ret);
> +
> +     return ret;
> +}
> +
>   static const struct vm_operations_struct xen_drm_drv_vm_ops = {
>       .open           = drm_gem_vm_open,
>       .close          = drm_gem_vm_close,
> @@ -67,6 +108,7 @@ static const struct drm_gem_object_funcs 
> xen_drm_front_gem_object_funcs = {
>       .get_sg_table = xen_drm_front_gem_get_sg_table,
>       .vmap = xen_drm_front_gem_prime_vmap,
>       .vunmap = xen_drm_front_gem_prime_vunmap,
> +     .mmap = xen_drm_front_gem_object_mmap,
>       .vm_ops = &xen_drm_drv_vm_ops,
>   };
>   
> @@ -238,58 +280,6 @@ xen_drm_front_gem_import_sg_table(struct drm_device *dev,
>       return &xen_obj->base;
>   }
>   
> -static int gem_mmap_obj(struct xen_gem_object *xen_obj,
> -                     struct vm_area_struct *vma)
> -{
> -     int ret;
> -
> -     /*
> -      * clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and set the
> -      * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want to map
> -      * the whole buffer.
> -      */
> -     vma->vm_flags &= ~VM_PFNMAP;
> -     vma->vm_flags |= VM_MIXEDMAP;
> -     vma->vm_pgoff = 0;
> -     /*
> -      * According to Xen on ARM ABI (xen/include/public/arch-arm.h):
> -      * all memory which is shared with other entities in the system
> -      * (including the hypervisor and other guests) must reside in memory
> -      * which is mapped as Normal Inner Write-Back Outer Write-Back
> -      * Inner-Shareable.
> -      */
> -     vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
> -
> -     /*
> -      * vm_operations_struct.fault handler will be called if CPU access
> -      * to VM is here. For GPUs this isn't the case, because CPU
> -      * doesn't touch the memory. Insert pages now, so both CPU and GPU are
> -      * happy.
> -      * FIXME: as we insert all the pages now then no .fault handler must
> -      * be called, so don't provide one
> -      */
> -     ret = vm_map_pages(vma, xen_obj->pages, xen_obj->num_pages);
> -     if (ret < 0)
> -             DRM_ERROR("Failed to map pages into vma: %d\n", ret);
> -
> -     return ret;
> -}
> -
> -int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma)
> -{
> -     struct xen_gem_object *xen_obj;
> -     struct drm_gem_object *gem_obj;
> -     int ret;
> -
> -     ret = drm_gem_mmap(filp, vma);
> -     if (ret < 0)
> -             return ret;
> -
> -     gem_obj = vma->vm_private_data;
> -     xen_obj = to_xen_gem_obj(gem_obj);
> -     return gem_mmap_obj(xen_obj, vma);
> -}
> -
>   int xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj, struct 
> dma_buf_map *map)
>   {
>       struct xen_gem_object *xen_obj = to_xen_gem_obj(gem_obj);
> @@ -313,17 +303,3 @@ void xen_drm_front_gem_prime_vunmap(struct 
> drm_gem_object *gem_obj,
>   {
>       vunmap(map->vaddr);
>   }
> -
> -int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj,
> -                              struct vm_area_struct *vma)
> -{
> -     struct xen_gem_object *xen_obj;
> -     int ret;
> -
> -     ret = drm_gem_mmap_obj(gem_obj, gem_obj->size, vma);
> -     if (ret < 0)
> -             return ret;
> -
> -     xen_obj = to_xen_gem_obj(gem_obj);
> -     return gem_mmap_obj(xen_obj, vma);
> -}
> diff --git a/drivers/gpu/drm/xen/xen_drm_front_gem.h 
> b/drivers/gpu/drm/xen/xen_drm_front_gem.h
> index a4e67d0a149c..eaea470f7001 100644
> --- a/drivers/gpu/drm/xen/xen_drm_front_gem.h
> +++ b/drivers/gpu/drm/xen/xen_drm_front_gem.h
> @@ -15,9 +15,7 @@ struct dma_buf_attachment;
>   struct dma_buf_map;
>   struct drm_device;
>   struct drm_gem_object;
> -struct file;
>   struct sg_table;
> -struct vm_area_struct;
>   
>   struct drm_gem_object *xen_drm_front_gem_create(struct drm_device *dev,
>                                               size_t size);
> @@ -33,15 +31,10 @@ struct page **xen_drm_front_gem_get_pages(struct 
> drm_gem_object *obj);
>   
>   void xen_drm_front_gem_free_object_unlocked(struct drm_gem_object *gem_obj);
>   
> -int xen_drm_front_gem_mmap(struct file *filp, struct vm_area_struct *vma);
> -
>   int xen_drm_front_gem_prime_vmap(struct drm_gem_object *gem_obj,
>                                struct dma_buf_map *map);
>   
>   void xen_drm_front_gem_prime_vunmap(struct drm_gem_object *gem_obj,
>                                   struct dma_buf_map *map);
>   
> -int xen_drm_front_gem_prime_mmap(struct drm_gem_object *gem_obj,
> -                              struct vm_area_struct *vma);
> -
>   #endif /* __XEN_DRM_FRONT_GEM_H */

 


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