On Mon, Jun 20, 2016 at 1:07 PM Chris Wilson <chris at chris-wilson.co.uk>
wrote:
> Enable the standard GEM dma-buf interface provided by the DRM core, but
> only for exporting the VGEM object. This allows passing around the VGEM
> objects created from the dumb interface and using them as sources
> elsewhere. Creating a VGEM object for a foriegn handle is not supported.
>
> v2: With additional completeness.
> v3: Need to clear the CPU cache upon exporting the dma-addresses.
>
> Testcase: igt/vgem_basic/dmabuf-*
> Testcase: igt/prime_vgem
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Sean Paul <seanpaul at chromium.org>
> Cc: Zach Reizner <zachr at google.com>
> ---
> drivers/gpu/drm/vgem/vgem_drv.c | 112
> +++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 111 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c
> b/drivers/gpu/drm/vgem/vgem_drv.c
> index e1a697d0662f..db48e837992d 100644
> --- a/drivers/gpu/drm/vgem/vgem_drv.c
> +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> @@ -193,14 +193,124 @@ static const struct file_operations
> vgem_driver_fops = {
> .release = drm_release,
> };
>
> +static void __put_pages(struct page **pages, long n_pages)
> +{
> + while (n_pages--)
> + put_page(pages[n_pages]);
> + drm_free_large(pages);
> +}
> +
> +static int vgem_prime_pin(struct drm_gem_object *obj)
> +{
> + long n_pages = obj->size >> PAGE_SHIFT;
> + struct page **pages;
> +
> + /* Flush the object from the CPU cache so that importers
> + * can rely on coherent indirect access via access the
> + * exported dma-address.
> + */
> + pages = drm_gem_get_pages(obj);
> + if (IS_ERR(pages))
> + return PTR_ERR(pages);
> +
> + drm_clflush_pages(pages, n_pages);
> + __put_pages(pages, n_pages);
> +
> + return 0;
> +}
> +
> +static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object
> *obj)
> +{
> + long n_pages = obj->size >> PAGE_SHIFT;
> + struct sg_table *st;
> + struct page **pages;
> + int ret;
> +
> + st = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
> + if (st == NULL)
> + return ERR_PTR(-ENOMEM);
> +
> + pages = drm_gem_get_pages(obj);
> + if (IS_ERR(pages)) {
> + ret = PTR_ERR(pages);
> + goto err;
> + }
> +
> + ret = sg_alloc_table_from_pages(st, pages, n_pages,
> + 0, obj->size, GFP_KERNEL);
> + __put_pages(pages, n_pages);
> + if (ret)
> + goto err;
> +
> + return st;
> +
> +err:
> + kfree(st);
> + return ERR_PTR(ret);
> +}
> +
> +static void *vgem_prime_vmap(struct drm_gem_object *obj)
> +{
> + long n_pages = obj->size >> PAGE_SHIFT;
> + struct page **pages;
> + void *addr;
> +
> + pages = drm_gem_get_pages(obj);
> + if (IS_ERR(pages))
> + return NULL;
> +
> + addr = vmap(pages, n_pages, 0,
> pgprot_writecombine(PAGE_KERNEL_IO));
> + __put_pages(pages, n_pages);
> +
> + return addr;
> +}
> +
> +static void vgem_prime_vunmap(struct drm_gem_object *obj, void *vaddr)
> +{
> + vunmap(vaddr);
> +}
> +
> +static int vgem_prime_mmap(struct drm_gem_object *obj,
> + struct vm_area_struct *vma)
> +{
> + int ret;
> +
> + if (obj->size < vma->vm_end - vma->vm_start)
> + return -EINVAL;
> +
> + if (!obj->filp)
> + return -ENODEV;
> +
> + ret = obj->filp->f_op->mmap(obj->filp, vma);
> + if (ret)
> + return ret;
> +
> + fput(vma->vm_file);
> + vma->vm_file = get_file(obj->filp);
> + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
> + vma->vm_page_prot =
> pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
> +
> + return 0;
> +}
> +
> static struct drm_driver vgem_driver = {
> - .driver_features = DRIVER_GEM,
> + .driver_features = DRIVER_GEM | DRIVER_PRIME,
> .gem_free_object_unlocked = vgem_gem_free_object,
> .gem_vm_ops = &vgem_gem_vm_ops,
> .ioctls = vgem_ioctls,
> .fops = &vgem_driver_fops,
> +
> .dumb_create = vgem_gem_dumb_create,
> .dumb_map_offset = vgem_gem_dumb_map,
> +
> + .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
> + .gem_prime_pin = vgem_prime_pin,
> + .gem_prime_export = drm_gem_prime_export,
> + .gem_prime_get_sg_table = vgem_prime_get_sg_table,
> + .gem_prime_vmap = vgem_prime_vmap,
> + .gem_prime_vunmap = vgem_prime_vunmap,
> + .gem_prime_mmap = vgem_prime_mmap,
> +
> .name = DRIVER_NAME,
> .desc = DRIVER_DESC,
> .date = DRIVER_DATE,
> --
> 2.8.1
>
>
Acked-by: Zach Reizner <zachr at google.com>
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