[Intel-gfx] [PATCH v4 4/4] drm/vgem: use shmem helpers
Thomas Zimmermann
tzimmermann at suse.de
Thu Jul 22 18:50:48 UTC 2021
Hi
Am 13.07.21 um 22:51 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)
>
> v4: I got tricked by 0cf2ef46c6c0 ("drm/shmem-helper: Use cached
> mappings by default"), and we need WC in vgem because vgem doesn't
> have explicit begin/end cpu access ioctls.
>
> Also add a comment why exactly vgem has to use wc.
>
> v5: Don't set obj->base.funcs, it will default to drm_gem_shmem_funcs
> (Thomas)
>
> v6: vgem also needs an MMU for remapping
>
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Acked-by: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: John Stultz <john.stultz at linaro.org>
> Cc: Sumit Semwal <sumit.semwal at linaro.org>
> Cc: "Christian König" <christian.koenig at amd.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> Cc: Melissa Wen <melissa.srw at gmail.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> ---
> drivers/gpu/drm/Kconfig | 5 +-
> drivers/gpu/drm/vgem/vgem_drv.c | 315 ++------------------------------
> 2 files changed, 15 insertions(+), 305 deletions(-)
>
> diff --git a/drivers/gpu/drm/Kconfig b/drivers/gpu/drm/Kconfig
> index 314eefa39892..28f7d2006e8b 100644
> --- a/drivers/gpu/drm/Kconfig
> +++ b/drivers/gpu/drm/Kconfig
> @@ -272,7 +272,8 @@ source "drivers/gpu/drm/kmb/Kconfig"
>
> config DRM_VGEM
> tristate "Virtual GEM provider"
> - depends on DRM
> + depends on DRM && MMU
> + 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.
> @@ -280,7 +281,7 @@ config DRM_VGEM
>
> config DRM_VKMS
> tristate "Virtual KMS (EXPERIMENTAL)"
> - depends on DRM
> + depends on DRM && MMU
> select DRM_KMS_HELPER
> select DRM_GEM_SHMEM_HELPER
> select CRC32
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index bf38a7e319d1..ba410ba6b7f7 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;
> @@ -159,81 +84,6 @@ 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),
> @@ -266,159 +116,23 @@ static const struct file_operations vgem_driver_fops = {
> .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)
> +static struct drm_gem_object *vgem_gem_create_object(struct drm_device *dev, size_t size)
> {
> - 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);
> -}
> + struct drm_gem_shmem_object *obj;
>
> -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);
> + obj = kzalloc(sizeof(*obj), GFP_KERNEL);
> + if (!obj)
> + return NULL;
>
> - /* Flush the object from the CPU cache so that importers can rely
> - * on coherent indirect access via the exported dma-address.
> + /*
> + * vgem doesn't have any begin/end cpu access ioctls, therefore must use
> + * coherent memory or dma-buf sharing just wont work.
> */
> - drm_clflush_pages(pages, n_pages);
Instead of shoehorning GEM SHMEM to get caching right (patch 2) have you
considered to set your own GEM funcs object for vgem. All function
pointers would point to SHMEM functions, except for pin, which would be
drm_gem_shmem_pin() + drm_clflush_pages(). If this works, I think it
would be much preferable to the current patch 2. You can override the
default GEM functions from within vgem_gem_create_object().
Best regards
Thomas
> -
> - 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->map_wc = true;
>
> - 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,
> -};
> -
> static const struct drm_driver vgem_driver = {
> .driver_features = DRIVER_GEM | DRIVER_RENDER,
> .open = vgem_open,
> @@ -427,13 +141,8 @@ 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,
> + .gem_create_object = vgem_gem_create_object,
>
> .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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: OpenPGP_signature
Type: application/pgp-signature
Size: 840 bytes
Desc: OpenPGP digital signature
URL: <https://lists.freedesktop.org/archives/intel-gfx/attachments/20210722/6c247ed4/attachment-0001.sig>
More information about the Intel-gfx
mailing list