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

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Hi

Am 26.02.21 um 14:30 schrieb Daniel Vetter:
On Fri, Feb 26, 2021 at 10:19 AM Thomas Zimmermann <tzimmermann@xxxxxxx> 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.

I didn't know that there was a rule for how to handle this. I just didn't like to have driver config rules in the main Kconfig file.

But yeah, maybe let's change this consistently in a separate patchset.

Best regards
Thomas

-Daniel



Best regards
Thomas


Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
Acked-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Cc: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: "Christian König" <christian.koenig@xxxxxxx>
Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
Cc: Melissa Wen <melissa.srw@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
   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




--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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