[RFC PATCH 2/2] drm/vgem: Enable dmabuf import interfaces

From: Laura Abbott
Date: Thu Apr 06 2017 - 19:19:04 EST


Enable the GEM dma-buf import interfaces in addition to the export
interfaces. This lets vgem be used as a test source for other allocators
(e.g. Ion).

Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
---
drivers/gpu/drm/vgem/vgem_drv.c | 135 ++++++++++++++++++++++++++++++++--------
drivers/gpu/drm/vgem/vgem_drv.h | 3 +
2 files changed, 111 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index b94feef..abc72e1 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -34,6 +34,9 @@
#include <linux/ramfs.h>
#include <linux/shmem_fs.h>
#include <linux/dma-buf.h>
+
+#include <drm/drmP.h>
+
#include "vgem_drv.h"

#define DRIVER_NAME "vgem"
@@ -42,40 +45,67 @@
#define DRIVER_MAJOR 1
#define DRIVER_MINOR 0

+#define VGEM_BO_IMPORT BIT(0)
+
+void vgem_gem_put_pages(struct drm_vgem_gem_object *obj)
+{
+ drm_gem_put_pages(&obj->base, obj->pages, false, false);
+ obj->pages = NULL;
+}
+
static void vgem_gem_free_object(struct drm_gem_object *obj)
{
struct drm_vgem_gem_object *vgem_obj = to_vgem_bo(obj);

+ if (vgem_obj->pages) {
+ if (vgem_obj->flags & VGEM_BO_IMPORT)
+ drm_free_large(vgem_obj->pages);
+ else
+ vgem_gem_put_pages(vgem_obj);
+ }
+
+ if (obj->import_attach)
+ drm_prime_gem_destroy(obj, vgem_obj->table);
+
drm_gem_object_release(obj);
kfree(vgem_obj);
}

+int vgem_gem_get_pages(struct drm_vgem_gem_object *obj)
+{
+ struct page **pages;
+
+ if (obj->pages)
+ return 0;
+
+ pages = drm_gem_get_pages(&obj->base);
+ if (IS_ERR(pages)) {
+ return PTR_ERR(pages);
+ }
+
+ obj->pages = pages;
+
+ return 0;
+}
+
static int 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;
- struct page *page;
+ loff_t num_pages;
+ pgoff_t page_offset;
+ page_offset = (vaddr - vma->vm_start) >> PAGE_SHIFT;

- page = shmem_read_mapping_page(file_inode(obj->base.filp)->i_mapping,
- (vaddr - vma->vm_start) >> PAGE_SHIFT);
- if (!IS_ERR(page)) {
- vmf->page = page;
- return 0;
- } else switch (PTR_ERR(page)) {
- case -ENOSPC:
- case -ENOMEM:
- return VM_FAULT_OOM;
- case -EBUSY:
- return VM_FAULT_RETRY;
- case -EFAULT:
- case -EINVAL:
- return VM_FAULT_SIGBUS;
- default:
- WARN_ON_ONCE(PTR_ERR(page));
- return VM_FAULT_SIGBUS;
- }
+ num_pages = DIV_ROUND_UP(obj->base.size, PAGE_SIZE);
+
+ if (page_offset > num_pages)
+ return VM_FAULT_SIGBUS;
+
+ get_page(obj->pages[page_offset]);
+ vmf->page = obj->pages[page_offset];
+ return 0;
}

static const struct vm_operations_struct vgem_gem_vm_ops = {
@@ -112,7 +142,30 @@ static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
kfree(vfile);
}

-/* ioctls */
+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);
+
+ ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
+ if (ret) {
+ kfree(obj);
+ return ERR_PTR(ret);
+ }
+
+ 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,
@@ -122,24 +175,25 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
struct drm_vgem_gem_object *obj;
int ret;

- obj = kzalloc(sizeof(*obj), GFP_KERNEL);
- if (!obj)
- return ERR_PTR(-ENOMEM);
+ obj = __vgem_gem_create(dev, size);
+ if (IS_ERR(obj))
+ return ERR_CAST(obj);

- ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
+ ret = vgem_gem_get_pages(obj);
if (ret)
goto err_free;

ret = drm_gem_handle_create(file, &obj->base, handle);
drm_gem_object_unreference_unlocked(&obj->base);
if (ret)
- goto err;
+ goto err_pages;

return &obj->base;

+err_pages:
+ vgem_gem_put_pages(obj);
err_free:
- kfree(obj);
-err:
+ __vgem_gem_destroy(obj);
return ERR_PTR(ret);
}

@@ -256,6 +310,30 @@ static struct sg_table *vgem_prime_get_sg_table(struct drm_gem_object *obj)
return st;
}

+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 = drm_malloc_ab(npages, sizeof(struct page *));
+ obj->flags = VGEM_BO_IMPORT;
+ if (!obj->pages) {
+ __vgem_gem_destroy(obj);
+ return ERR_PTR(-ENOMEM);
+ }
+ drm_prime_sg_to_page_addr_arrays(obj->table, obj->pages, NULL,
+ npages);
+ return &obj->base;
+}
+
static void *vgem_prime_vmap(struct drm_gem_object *obj)
{
long n_pages = obj->size >> PAGE_SHIFT;
@@ -314,8 +392,11 @@ static struct drm_driver vgem_driver = {
.dumb_map_offset = vgem_gem_dumb_map,

.prime_handle_to_fd = drm_gem_prime_handle_to_fd,
+ .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
.gem_prime_pin = vgem_prime_pin,
+ .gem_prime_import = drm_gem_prime_import,
.gem_prime_export = drm_gem_prime_export,
+ .gem_prime_import_sg_table = vgem_prime_import_sg_table,
.gem_prime_get_sg_table = vgem_prime_get_sg_table,
.gem_prime_vmap = vgem_prime_vmap,
.gem_prime_vunmap = vgem_prime_vunmap,
diff --git a/drivers/gpu/drm/vgem/vgem_drv.h b/drivers/gpu/drm/vgem/vgem_drv.h
index cb59c7a..f5dd076 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -43,6 +43,9 @@ struct vgem_file {
#define to_vgem_bo(x) container_of(x, struct drm_vgem_gem_object, base)
struct drm_vgem_gem_object {
struct drm_gem_object base;
+ struct page **pages;
+ struct sg_table *table;
+ unsigned long flags;
};

int vgem_fence_open(struct vgem_file *file);
--
2.7.4