Re: [PATCH] drm/vgem: use shmem helpers

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Fri, Feb 26, 2021 at 10:19 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>
> Hi
>
> Am 25.02.21 um 11:23 schrieb Daniel Vetter:
> > Aside from deleting lots of code the real motivation here is to switch
> > the mmap over to VM_PFNMAP, to be more consistent with what real gpu
> > drivers do. They're all VM_PFNMP, which means get_user_pages doesn't
> > work, and even if you try and there's a struct page behind that,
> > touching it and mucking around with its refcount can upset drivers
> > real bad.
> >
> > v2: Review from Thomas:
> > - sort #include
> > - drop more dead code that I didn't spot somehow
> >
> > v3: select DRM_GEM_SHMEM_HELPER to make it build (intel-gfx-ci)
>
> Since you're working on it, could you move the config item into a
> Kconfig file under vgem?

We have a lot of drivers still without their own Kconfig. I thought
we're only doing that for drivers which have multiple options, or
otherwise would clutter up the main drm/Kconfig file?

Not opposed to this, just feels like if we do this, should do it for
all of them.
-Daniel


>
> Best regards
> Thomas
>
> >
> > Cc: Thomas Zimmermann <tzimmermann@suse.de>
> > Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
> > Cc: John Stultz <john.stultz@linaro.org>
> > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > Cc: "Christian König" <christian.koenig@amd.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> > Cc: Melissa Wen <melissa.srw@gmail.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > ---
> >   drivers/gpu/drm/Kconfig         |   1 +
> >   drivers/gpu/drm/vgem/vgem_drv.c | 340 +-------------------------------
> >   2 files changed, 4 insertions(+), 337 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> > index 8e73311de583..94e4ac830283 100644
> > --- a/drivers/gpu/drm/Kconfig
> > +++ b/drivers/gpu/drm/Kconfig
> > @@ -274,6 +274,7 @@ source "drivers/gpu/drm/kmb/Kconfig"
> >   config DRM_VGEM
> >       tristate "Virtual GEM provider"
> >       depends on DRM
> > +     select DRM_GEM_SHMEM_HELPER
> >       help
> >         Choose this option to get a virtual graphics memory manager,
> >         as used by Mesa's software renderer for enhanced performance.
> > diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> > index a0e75f1d5d01..b1b3a5ffc542 100644
> > --- a/drivers/gpu/drm/vgem/vgem_drv.c
> > +++ b/drivers/gpu/drm/vgem/vgem_drv.c
> > @@ -38,6 +38,7 @@
> >
> >   #include <drm/drm_drv.h>
> >   #include <drm/drm_file.h>
> > +#include <drm/drm_gem_shmem_helper.h>
> >   #include <drm/drm_ioctl.h>
> >   #include <drm/drm_managed.h>
> >   #include <drm/drm_prime.h>
> > @@ -50,87 +51,11 @@
> >   #define DRIVER_MAJOR        1
> >   #define DRIVER_MINOR        0
> >
> > -static const struct drm_gem_object_funcs vgem_gem_object_funcs;
> > -
> >   static struct vgem_device {
> >       struct drm_device drm;
> >       struct platform_device *platform;
> >   } *vgem_device;
> >
> > -static void vgem_gem_free_object(struct drm_gem_object *obj)
> > -{
> > -     struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);
> > -
> > -     kvfree(vgem_obj->pages);
> > -     mutex_destroy(&vgem_obj->pages_lock);
> > -
> > -     if (obj->import_attach)
> > -             drm_prime_gem_destroy(obj, vgem_obj->table);
> > -
> > -     drm_gem_object_release(obj);
> > -     kfree(vgem_obj);
> > -}
> > -
> > -static vm_fault_t vgem_gem_fault(struct vm_fault *vmf)
> > -{
> > -     struct vm_area_struct *vma = vmf->vma;
> > -     struct drm_vgem_gem_object *obj = vma->vm_private_data;
> > -     /* We don't use vmf->pgoff since that has the fake offset */
> > -     unsigned long vaddr = vmf->address;
> > -     vm_fault_t ret = VM_FAULT_SIGBUS;
> > -     loff_t num_pages;
> > -     pgoff_t page_offset;
> > -     page_offset = (vaddr - vma->vm_start) >> PAGE_SHIFT;
> > -
> > -     num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
> > -
> > -     if (page_offset >= num_pages)
> > -             return VM_FAULT_SIGBUS;
> > -
> > -     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;
> > -
> > -             page = shmem_read_mapping_page(
> > -                                     file_inode(obj->base.filp)->i_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;
> > -}
> > -
> > -static const struct vm_operations_struct vgem_gem_vm_ops = {
> > -     .fault = vgem_gem_fault,
> > -     .open = drm_gem_vm_open,
> > -     .close = drm_gem_vm_close,
> > -};
> > -
> >   static int vgem_open(struct drm_device *dev, struct drm_file *file)
> >   {
> >       struct vgem_file *vfile;
> > @@ -159,265 +84,12 @@ static void vgem_postclose(struct drm_device *dev, struct drm_file *file)
> >       kfree(vfile);
> >   }
> >
> > -static struct drm_vgem_gem_object *__vgem_gem_create(struct drm_device *dev,
> > -                                             unsigned long size)
> > -{
> > -     struct drm_vgem_gem_object *obj;
> > -     int ret;
> > -
> > -     obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> > -     if (!obj)
> > -             return ERR_PTR(-ENOMEM);
> > -
> > -     obj->base.funcs = &vgem_gem_object_funcs;
> > -
> > -     ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
> > -     if (ret) {
> > -             kfree(obj);
> > -             return ERR_PTR(ret);
> > -     }
> > -
> > -     mutex_init(&obj->pages_lock);
> > -
> > -     return obj;
> > -}
> > -
> > -static void __vgem_gem_destroy(struct drm_vgem_gem_object *obj)
> > -{
> > -     drm_gem_object_release(&obj->base);
> > -     kfree(obj);
> > -}
> > -
> > -static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
> > -                                           struct drm_file *file,
> > -                                           unsigned int *handle,
> > -                                           unsigned long size)
> > -{
> > -     struct drm_vgem_gem_object *obj;
> > -     int ret;
> > -
> > -     obj = __vgem_gem_create(dev, size);
> > -     if (IS_ERR(obj))
> > -             return ERR_CAST(obj);
> > -
> > -     ret = drm_gem_handle_create(file, &obj->base, handle);
> > -     if (ret) {
> > -             drm_gem_object_put(&obj->base);
> > -             return ERR_PTR(ret);
> > -     }
> > -
> > -     return &obj->base;
> > -}
> > -
> > -static int vgem_gem_dumb_create(struct drm_file *file, struct drm_device *dev,
> > -                             struct drm_mode_create_dumb *args)
> > -{
> > -     struct drm_gem_object *gem_object;
> > -     u64 pitch, size;
> > -
> > -     pitch = args->width * DIV_ROUND_UP(args->bpp, 8);
> > -     size = args->height * pitch;
> > -     if (size == 0)
> > -             return -EINVAL;
> > -
> > -     gem_object = vgem_gem_create(dev, file, &args->handle, size);
> > -     if (IS_ERR(gem_object))
> > -             return PTR_ERR(gem_object);
> > -
> > -     args->size = gem_object->size;
> > -     args->pitch = pitch;
> > -
> > -     drm_gem_object_put(gem_object);
> > -
> > -     DRM_DEBUG("Created object of size %llu\n", args->size);
> > -
> > -     return 0;
> > -}
> > -
> >   static struct drm_ioctl_desc vgem_ioctls[] = {
> >       DRM_IOCTL_DEF_DRV(VGEM_FENCE_ATTACH, vgem_fence_attach_ioctl, DRM_RENDER_ALLOW),
> >       DRM_IOCTL_DEF_DRV(VGEM_FENCE_SIGNAL, vgem_fence_signal_ioctl, DRM_RENDER_ALLOW),
> >   };
> >
> > -static int vgem_mmap(struct file *filp, struct vm_area_struct *vma)
> > -{
> > -     unsigned long flags = vma->vm_flags;
> > -     int ret;
> > -
> > -     ret = drm_gem_mmap(filp, vma);
> > -     if (ret)
> > -             return ret;
> > -
> > -     /* Keep the WC mmaping set by drm_gem_mmap() but our pages
> > -      * are ordinary and not special.
> > -      */
> > -     vma->vm_flags = flags | VM_DONTEXPAND | VM_DONTDUMP;
> > -     return 0;
> > -}
> > -
> > -static const struct file_operations vgem_driver_fops = {
> > -     .owner          = THIS_MODULE,
> > -     .open           = drm_open,
> > -     .mmap           = vgem_mmap,
> > -     .poll           = drm_poll,
> > -     .read           = drm_read,
> > -     .unlocked_ioctl = drm_ioctl,
> > -     .compat_ioctl   = drm_compat_ioctl,
> > -     .release        = drm_release,
> > -};
> > -
> > -static struct page **vgem_pin_pages(struct drm_vgem_gem_object *bo)
> > -{
> > -     mutex_lock(&bo->pages_lock);
> > -     if (bo->pages_pin_count++ == 0) {
> > -             struct page **pages;
> > -
> > -             pages = drm_gem_get_pages(&bo->base);
> > -             if (IS_ERR(pages)) {
> > -                     bo->pages_pin_count--;
> > -                     mutex_unlock(&bo->pages_lock);
> > -                     return pages;
> > -             }
> > -
> > -             bo->pages = pages;
> > -     }
> > -     mutex_unlock(&bo->pages_lock);
> > -
> > -     return bo->pages;
> > -}
> > -
> > -static void vgem_unpin_pages(struct drm_vgem_gem_object *bo)
> > -{
> > -     mutex_lock(&bo->pages_lock);
> > -     if (--bo->pages_pin_count == 0) {
> > -             drm_gem_put_pages(&bo->base, bo->pages, true, true);
> > -             bo->pages = NULL;
> > -     }
> > -     mutex_unlock(&bo->pages_lock);
> > -}
> > -
> > -static int vgem_prime_pin(struct drm_gem_object *obj)
> > -{
> > -     struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > -     long n_pages = obj->size >> PAGE_SHIFT;
> > -     struct page **pages;
> > -
> > -     pages = vgem_pin_pages(bo);
> > -     if (IS_ERR(pages))
> > -             return PTR_ERR(pages);
> > -
> > -     /* Flush the object from the CPU cache so that importers can rely
> > -      * on coherent indirect access via the exported dma-address.
> > -      */
> > -     drm_clflush_pages(pages, n_pages);
> > -
> > -     return 0;
> > -}
> > -
> > -static void vgem_prime_unpin(struct drm_gem_object *obj)
> > -{
> > -     struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > -
> > -     vgem_unpin_pages(bo);
> > -}
> > -
> > -static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
> > -{
> > -     struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > -
> > -     return drm_prime_pages_to_sg(obj->dev, bo->pages, bo->base.size >> PAGE_SHIFT);
> > -}
> > -
> > -static struct drm_gem_object* vgem_prime_import(struct drm_device *dev,
> > -                                             struct dma_buf *dma_buf)
> > -{
> > -     struct vgem_device *vgem = container_of(dev, typeof(*vgem), drm);
> > -
> > -     return drm_gem_prime_import_dev(dev, dma_buf, &vgem->platform->dev);
> > -}
> > -
> > -static struct drm_gem_object *vgem_prime_import_sg_table(struct drm_device *dev,
> > -                     struct dma_buf_attachment *attach, struct sg_table *sg)
> > -{
> > -     struct drm_vgem_gem_object *obj;
> > -     int npages;
> > -
> > -     obj = __vgem_gem_create(dev, attach->dmabuf->size);
> > -     if (IS_ERR(obj))
> > -             return ERR_CAST(obj);
> > -
> > -     npages = PAGE_ALIGN(attach->dmabuf->size) / PAGE_SIZE;
> > -
> > -     obj->table = sg;
> > -     obj->pages = kvmalloc_array(npages, sizeof(struct page *), GFP_KERNEL);
> > -     if (!obj->pages) {
> > -             __vgem_gem_destroy(obj);
> > -             return ERR_PTR(-ENOMEM);
> > -     }
> > -
> > -     obj->pages_pin_count++; /* perma-pinned */
> > -     drm_prime_sg_to_page_array(obj->table, obj->pages, npages);
> > -     return &obj->base;
> > -}
> > -
> > -static int vgem_prime_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
> > -{
> > -     struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > -     long n_pages = obj->size >> PAGE_SHIFT;
> > -     struct page **pages;
> > -     void *vaddr;
> > -
> > -     pages = vgem_pin_pages(bo);
> > -     if (IS_ERR(pages))
> > -             return PTR_ERR(pages);
> > -
> > -     vaddr = vmap(pages, n_pages, 0, pgprot_writecombine(PAGE_KERNEL));
> > -     if (!vaddr)
> > -             return -ENOMEM;
> > -     dma_buf_map_set_vaddr(map, vaddr);
> > -
> > -     return 0;
> > -}
> > -
> > -static void vgem_prime_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
> > -{
> > -     struct drm_vgem_gem_object *bo = to_vgem_bo(obj);
> > -
> > -     vunmap(map->vaddr);
> > -     vgem_unpin_pages(bo);
> > -}
> > -
> > -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 = call_mmap(obj->filp, vma);
> > -     if (ret)
> > -             return ret;
> > -
> > -     vma_set_file(vma, 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 const struct drm_gem_object_funcs vgem_gem_object_funcs = {
> > -     .free = vgem_gem_free_object,
> > -     .pin = vgem_prime_pin,
> > -     .unpin = vgem_prime_unpin,
> > -     .get_sg_table = vgem_prime_get_sg_table,
> > -     .vmap = vgem_prime_vmap,
> > -     .vunmap = vgem_prime_vunmap,
> > -     .vm_ops = &vgem_gem_vm_ops,
> > -};
> > +DEFINE_DRM_GEM_FOPS(vgem_driver_fops);
> >
> >   static const struct drm_driver vgem_driver = {
> >       .driver_features                = DRIVER_GEM | DRIVER_RENDER,
> > @@ -427,13 +99,7 @@ static const struct drm_driver vgem_driver = {
> >       .num_ioctls                     = ARRAY_SIZE(vgem_ioctls),
> >       .fops                           = &vgem_driver_fops,
> >
> > -     .dumb_create                    = vgem_gem_dumb_create,
> > -
> > -     .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
> > -     .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
> > -     .gem_prime_import = vgem_prime_import,
> > -     .gem_prime_import_sg_table = vgem_prime_import_sg_table,
> > -     .gem_prime_mmap = vgem_prime_mmap,
> > +     DRM_GEM_SHMEM_DRIVER_OPS,
> >
> >       .name   = DRIVER_NAME,
> >       .desc   = DRIVER_DESC,
> >
>
> --
> Thomas Zimmermann
> Graphics Driver Developer
> SUSE Software Solutions Germany GmbH
> Maxfeldstr. 5, 90409 Nürnberg, Germany
> (HRB 36809, AG Nürnberg)
> Geschäftsführer: Felix Imendörffer
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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