Re: [PATCH V2 1/5] drm/vkms: Add dumb operations

[Haneen Mohammed <hamohammed.sa@gmail.com>]

On Thu, Jun 21, 2018 at 09:16:13AM -0300, Rodrigo Siqueira wrote:
> VKMS currently does not handle dumb data, and as a consequence, it does
> not provide mechanisms for handling gem. This commit adds the necessary
> support for gem object/handler and the dumb functions.
> 
> Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
> ---

This looks good to me except with missing gem_free_object_unlocked callback,
which causes warning: Memory manager not clean during takedown. 

Maybe it will be easier if we add this in another patch instead of creating v3 of
this patchset?

>  drivers/gpu/drm/vkms/Makefile   |   2 +-
>  drivers/gpu/drm/vkms/vkms_drv.c |   9 ++
>  drivers/gpu/drm/vkms/vkms_drv.h |  21 ++++
>  drivers/gpu/drm/vkms/vkms_gem.c | 168 ++++++++++++++++++++++++++++++++
>  4 files changed, 199 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/gpu/drm/vkms/vkms_gem.c
> 
> diff --git a/drivers/gpu/drm/vkms/Makefile b/drivers/gpu/drm/vkms/Makefile
> index 3f774a6a9c58..986297da51bf 100644
> --- a/drivers/gpu/drm/vkms/Makefile
> +++ b/drivers/gpu/drm/vkms/Makefile
> @@ -1,3 +1,3 @@
> -vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o
> +vkms-y := vkms_drv.o vkms_plane.o vkms_output.o vkms_crtc.o vkms_gem.o
>  
>  obj-$(CONFIG_DRM_VKMS) += vkms.o
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.c b/drivers/gpu/drm/vkms/vkms_drv.c
> index 740a4cbfed91..638bab9083b5 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.c
> +++ b/drivers/gpu/drm/vkms/vkms_drv.c
> @@ -37,6 +37,12 @@ static const struct file_operations vkms_driver_fops = {
>  	.release	= drm_release,
>  };
>  
> +static const struct vm_operations_struct vkms_gem_vm_ops = {
> +	.fault = vkms_gem_fault,
> +	.open = drm_gem_vm_open,
> +	.close = drm_gem_vm_close,
> +};
> +
>  static void vkms_release(struct drm_device *dev)
>  {
>  	struct vkms_device *vkms = container_of(dev, struct vkms_device, drm);
> @@ -50,6 +56,9 @@ static struct drm_driver vkms_driver = {
>  	.driver_features	= DRIVER_MODESET | DRIVER_ATOMIC | DRIVER_GEM,
>  	.release		= vkms_release,
>  	.fops			= &vkms_driver_fops,
> +	.dumb_create		= vkms_dumb_create,
> +	.dumb_map_offset	= vkms_dumb_map,
> +	.gem_vm_ops		= &vkms_gem_vm_ops,
>  
>  	.name			= DRIVER_NAME,
>  	.desc			= DRIVER_DESC,
> diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> index b0f9d2e61a42..54bb3dd2b2c1 100644
> --- a/drivers/gpu/drm/vkms/vkms_drv.h
> +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> @@ -3,6 +3,7 @@
>  
>  #include <drm/drmP.h>
>  #include <drm/drm.h>
> +#include <drm/drm_gem.h>
>  #include <drm/drm_encoder.h>
>  
>  static const u32 vkms_formats[] = {
> @@ -21,6 +22,12 @@ struct vkms_device {
>  	struct vkms_output output;
>  };
>  
> +struct vkms_gem_object {
> +	struct drm_gem_object gem;
> +	struct mutex pages_lock; /* Page lock used in page fault handler */
> +	struct page **pages;
> +};
> +
>  int vkms_crtc_init(struct drm_device *dev, struct drm_crtc *crtc,
>  		   struct drm_plane *primary, struct drm_plane *cursor);
>  
> @@ -28,4 +35,18 @@ int vkms_output_init(struct vkms_device *vkmsdev);
>  
>  struct drm_plane *vkms_plane_init(struct vkms_device *vkmsdev);
>  
> +/* Gem stuff */
> +struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
> +				       struct drm_file *file,
> +				       u32 *handle,
> +				       u64 size);
> +
> +int vkms_gem_fault(struct vm_fault *vmf);
> +
> +int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
> +		     struct drm_mode_create_dumb *args);
> +
> +int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
> +		  u32 handle, u64 *offset);
> +
>  #endif /* _VKMS_DRV_H_ */
> diff --git a/drivers/gpu/drm/vkms/vkms_gem.c b/drivers/gpu/drm/vkms/vkms_gem.c
> new file mode 100644
> index 000000000000..9f820f56b9e0
> --- /dev/null
> +++ b/drivers/gpu/drm/vkms/vkms_gem.c
> @@ -0,0 +1,168 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/shmem_fs.h>
> +
> +#include "vkms_drv.h"
> +
> +static struct vkms_gem_object *__vkms_gem_create(struct drm_device *dev,
> +						 u64 size)
> +{
> +	struct vkms_gem_object *obj;
> +	int ret;
> +
> +	obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> +	if (!obj)
> +		return ERR_PTR(-ENOMEM);
> +
> +	size = roundup(size, PAGE_SIZE);
> +	ret = drm_gem_object_init(dev, &obj->gem, size);
> +	if (ret) {
> +		kfree(obj);
> +		return ERR_PTR(ret);
> +	}
> +
> +	mutex_init(&obj->pages_lock);
> +
> +	return obj;
> +}
> +
> +int vkms_gem_fault(struct vm_fault *vmf)
> +{
> +	struct vm_area_struct *vma = vmf->vma;
> +	struct vkms_gem_object *obj = vma->vm_private_data;
> +	unsigned long vaddr = vmf->address;
> +	pgoff_t page_offset;
> +	loff_t num_pages;
> +	int ret;
> +
> +	page_offset = (vaddr - vma->vm_start) >> PAGE_SHIFT;
> +	num_pages = DIV_ROUND_UP(obj->gem.size, PAGE_SIZE);
> +
> +	if (page_offset > num_pages)
> +		return VM_FAULT_SIGBUS;
> +
> +	ret = -ENOENT;
> +	mutex_lock(&obj->pages_lock);
> +	if (obj->pages) {
> +		get_page(obj->pages[page_offset]);
> +		vmf->page = obj->pages[page_offset];
> +		ret = 0;
> +	}
> +	mutex_unlock(&obj->pages_lock);
> +	if (ret) {
> +		struct page *page;
> +		struct address_space *mapping;
> +
> +		mapping = file_inode(obj->gem.filp)->i_mapping;
> +		page = shmem_read_mapping_page(mapping, page_offset);
> +
> +		if (!IS_ERR(page)) {
> +			vmf->page = page;
> +			ret = 0;
> +		} else {
> +			switch (PTR_ERR(page)) {
> +			case -ENOSPC:
> +			case -ENOMEM:
> +				ret = VM_FAULT_OOM;
> +				break;
> +			case -EBUSY:
> +				ret = VM_FAULT_RETRY;
> +				break;
> +			case -EFAULT:
> +			case -EINVAL:
> +				ret = VM_FAULT_SIGBUS;
> +				break;
> +			default:
> +				WARN_ON(PTR_ERR(page));
> +				ret = VM_FAULT_SIGBUS;
> +				break;
> +			}
> +		}
> +	}
> +	return ret;
> +}
> +
> +struct drm_gem_object *vkms_gem_create(struct drm_device *dev,
> +				       struct drm_file *file,
> +				       u32 *handle,
> +				       u64 size)
> +{
> +	struct vkms_gem_object *obj;
> +	int ret;
> +
> +	if (!file || !dev || !handle)
> +		return ERR_PTR(-EINVAL);
> +
> +	obj = __vkms_gem_create(dev, size);
> +	if (IS_ERR(obj))
> +		return ERR_CAST(obj);
> +
> +	ret = drm_gem_handle_create(file, &obj->gem, handle);
> +	drm_gem_object_put_unlocked(&obj->gem);
> +	if (ret) {
> +		drm_gem_object_release(&obj->gem);
> +		kfree(obj);
> +		return ERR_PTR(ret);
> +	}
> +
> +	return &obj->gem;
> +}
> +
> +int vkms_dumb_create(struct drm_file *file, struct drm_device *dev,
> +		     struct drm_mode_create_dumb *args)
> +{
> +	struct drm_gem_object *gem_obj;
> +	u64 pitch, size;
> +
> +	if (!args || !dev || !file)
> +		return -EINVAL;
> +
> +	pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
> +	size = pitch * args->height;
> +
> +	if (!size)
> +		return -EINVAL;
> +
> +	gem_obj = vkms_gem_create(dev, file, &args->handle, size);
> +	if (IS_ERR(gem_obj))
> +		return PTR_ERR(gem_obj);
> +
> +	args->size = gem_obj->size;
> +	args->pitch = pitch;
> +
> +	DRM_DEBUG_DRIVER("Created object of size %lld\n", size);
> +
> +	return 0;
> +}
> +
> +int vkms_dumb_map(struct drm_file *file, struct drm_device *dev,
> +		  u32 handle, u64 *offset)
> +{
> +	struct drm_gem_object *obj;
> +	int ret;
> +
> +	obj = drm_gem_object_lookup(file, handle);
> +	if (!obj)
> +		return -ENOENT;
> +
> +	if (!obj->filp) {
> +		ret = -EINVAL;
> +		goto unref;
> +	}
> +
> +	ret = drm_gem_create_mmap_offset(obj);
> +	if (ret)
> +		goto unref;
> +
> +	*offset = drm_vma_node_offset_addr(&obj->vma_node);
> +unref:
> +	drm_gem_object_put_unlocked(obj);
> +
> +	return ret;
> +}
> -- 
> 2.17.1
> 
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