[RFC PATCHv2 0/3] dma_buf import support for vgem

[RFC PATCHv2 0/3] dma_buf import support for vgem

[Laura Abbott]

Hi,

This is v2 of my proposal to add dma_buf import functions for vgem.
Big changes from v1:

- A device is required for dma_buf attach to work. The existing vgem driver
intentionally does not use one as it provides a good way to test the DRM
framework. This approach instead puts a dummy platform device in the existing
drm_device->platformdev field and uses that for attaching.
- Native vgem buffers can still be faulted in a page at a time without
requiring the entire buffer be resident in memory.

I'm still marking this as RFC as I haven't had a chance to finish
a userspace test that can be integrated into igt.

Feedback appreciated as always.

Thanks,
Laura

Laura Abbott (3):
  drm/vgem: Add a dummy platform device
  drm/prime: Introduce drm_gem_prime_import_platform
  drm/vgem: Enable dmabuf import interfaces

 drivers/gpu/drm/drm_prime.c     |  23 +++++-
 drivers/gpu/drm/vgem/vgem_drv.c | 150 +++++++++++++++++++++++++++++++---------
 drivers/gpu/drm/vgem/vgem_drv.h |   2 +
 include/drm/drmP.h              |   5 ++
 4 files changed, 145 insertions(+), 35 deletions(-)

-- 
2.7.4

[RFC PATCHv2 1/3] drm/vgem: Add a dummy platform device

[Laura Abbott]

The vgem driver is currently registered independent of any actual
device. Some usage of the dmabuf APIs require an actual device structure
to do anything. Register a dummy platform device for use with dmabuf.

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
v2: Store the platform device in the platformdev field instead of the
regular device structure.
---
 drivers/gpu/drm/vgem/vgem_drv.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index a1f42d1..1b02e56 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.c
+++ b/drivers/gpu/drm/vgem/vgem_drv.c
@@ -335,11 +335,20 @@ static int __init vgem_init(void)
 	int ret;
 
 	vgem_device = drm_dev_alloc(&vgem_driver, NULL);
-	if (IS_ERR(vgem_device)) {
-		ret = PTR_ERR(vgem_device);
+	if (IS_ERR(vgem_device))
+		return PTR_ERR(vgem_device);
+
+	vgem_device->platformdev = platform_device_register_simple("vgem",
+					-1, NULL, 0);
+
+	if (!vgem_device->platformdev) {
+		ret = -ENODEV;
 		goto out;
 	}
 
+	dma_coerce_mask_and_coherent(&vgem_device->platformdev->dev,
+					DMA_BIT_MASK(64));
+
 	ret  = drm_dev_register(vgem_device, 0);
 	if (ret)
 		goto out_unref;
@@ -347,13 +356,15 @@ static int __init vgem_init(void)
 	return 0;
 
 out_unref:
-	drm_dev_unref(vgem_device);
+	platform_device_unregister(vgem_device->platformdev);
 out:
+	drm_dev_unref(vgem_device);
 	return ret;
 }
 
 static void __exit vgem_exit(void)
 {
+	platform_device_unregister(vgem_device->platformdev);
 	drm_dev_unregister(vgem_device);
 	drm_dev_unref(vgem_device);
 }
-- 
2.7.4

[RFC PATCHv2 2/3] drm/prime: Introduce drm_gem_prime_import_platform

[Laura Abbott]

The existing drm_gem_prime_import function uses the underlying
struct device of a drm_device for attaching to a dma_buf. Some drivers
(notably vgem) may not have an underlying device structure. Offer
an alternate function to attach using a platform device associated
with drm_device.

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
New approach for v2
---
 drivers/gpu/drm/drm_prime.c | 23 ++++++++++++++++++++---
 include/drm/drmP.h          |  5 +++++
 2 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 25aa455..5486248 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -601,8 +601,9 @@ EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
  * This is the implementation of the gem_prime_import functions for GEM drivers
  * using the PRIME helpers.
  */
-struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
-					    struct dma_buf *dma_buf)
+static struct drm_gem_object *__drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf,
+					    struct device *attach_dev)
 {
 	struct dma_buf_attachment *attach;
 	struct sg_table *sgt;
@@ -624,7 +625,7 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 	if (!dev->driver->gem_prime_import_sg_table)
 		return ERR_PTR(-EINVAL);
 
-	attach = dma_buf_attach(dma_buf, dev->dev);
+	attach = dma_buf_attach(dma_buf, attach_dev);
 	if (IS_ERR(attach))
 		return ERR_CAST(attach);
 
@@ -654,8 +655,24 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 
 	return ERR_PTR(ret);
 }
+
+struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	return __drm_gem_prime_import(dev, dma_buf, dev->dev);
+}
 EXPORT_SYMBOL(drm_gem_prime_import);
 
+struct drm_gem_object *drm_gem_prime_import_platform(struct drm_device *dev,
+					    struct dma_buf *dma_buf)
+{
+	if (WARN_ON_ONCE(!dev->platformdev))
+		return NULL;
+
+	return __drm_gem_prime_import(dev, dma_buf, &dev->platformdev->dev);
+}
+EXPORT_SYMBOL(drm_gem_prime_import_platform);
+
 /**
  * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
  * @dev: dev to export the buffer from
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 6105c05..f4ac30f 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -769,6 +769,11 @@ extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
 		int *prime_fd);
 extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
 		struct dma_buf *dma_buf);
+
+extern struct drm_gem_object *drm_gem_prime_import_platform(
+		struct drm_device *dev,
+		struct dma_buf *dma_buf);
+
 extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
 		struct drm_file *file_priv, int prime_fd, uint32_t *handle);
 struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
-- 
2.7.4

Re: [RFC PATCHv2 2/3] drm/prime: Introduce drm_gem_prime_import_platform

[Daniel Vetter]

On Wed, Apr 26, 2017 at 02:12:29PM -0700, Laura Abbott wrote:
> The existing drm_gem_prime_import function uses the underlying
> struct device of a drm_device for attaching to a dma_buf. Some drivers
> (notably vgem) may not have an underlying device structure. Offer
> an alternate function to attach using a platform device associated
> with drm_device.
> 
> Signed-off-by: Laura Abbott <labbott@redhat.com>
> ---
> New approach for v2

This conflicts with patches already in drm-misc.git/drm-misc-next. Can you
pls rebase (and then also pls add the missing kerneldoc for the new
drm_gem_prime_import_platform function, plus links between the two any
why they exists/when to use each)?

Noticed this when I tried to apply them.

Pls keep Chris' r-b on the patch when resending.

Thanks, Daniel
> ---
>  drivers/gpu/drm/drm_prime.c | 23 ++++++++++++++++++++---
>  include/drm/drmP.h          |  5 +++++
>  2 files changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
> index 25aa455..5486248 100644
> --- a/drivers/gpu/drm/drm_prime.c
> +++ b/drivers/gpu/drm/drm_prime.c
> @@ -601,8 +601,9 @@ EXPORT_SYMBOL(drm_gem_prime_handle_to_fd);
>   * This is the implementation of the gem_prime_import functions for GEM drivers
>   * using the PRIME helpers.
>   */
> -struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
> -					    struct dma_buf *dma_buf)
> +static struct drm_gem_object *__drm_gem_prime_import(struct drm_device *dev,
> +					    struct dma_buf *dma_buf,
> +					    struct device *attach_dev)
>  {
>  	struct dma_buf_attachment *attach;
>  	struct sg_table *sgt;
> @@ -624,7 +625,7 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
>  	if (!dev->driver->gem_prime_import_sg_table)
>  		return ERR_PTR(-EINVAL);
>  
> -	attach = dma_buf_attach(dma_buf, dev->dev);
> +	attach = dma_buf_attach(dma_buf, attach_dev);
>  	if (IS_ERR(attach))
>  		return ERR_CAST(attach);
>  
> @@ -654,8 +655,24 @@ struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
>  
>  	return ERR_PTR(ret);
>  }
> +
> +struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
> +					    struct dma_buf *dma_buf)
> +{
> +	return __drm_gem_prime_import(dev, dma_buf, dev->dev);
> +}
>  EXPORT_SYMBOL(drm_gem_prime_import);
>  
> +struct drm_gem_object *drm_gem_prime_import_platform(struct drm_device *dev,
> +					    struct dma_buf *dma_buf)
> +{
> +	if (WARN_ON_ONCE(!dev->platformdev))
> +		return NULL;
> +
> +	return __drm_gem_prime_import(dev, dma_buf, &dev->platformdev->dev);
> +}
> +EXPORT_SYMBOL(drm_gem_prime_import_platform);
> +
>  /**
>   * drm_gem_prime_fd_to_handle - PRIME import function for GEM drivers
>   * @dev: dev to export the buffer from
> diff --git a/include/drm/drmP.h b/include/drm/drmP.h
> index 6105c05..f4ac30f 100644
> --- a/include/drm/drmP.h
> +++ b/include/drm/drmP.h
> @@ -769,6 +769,11 @@ extern int drm_gem_prime_handle_to_fd(struct drm_device *dev,
>  		int *prime_fd);
>  extern struct drm_gem_object *drm_gem_prime_import(struct drm_device *dev,
>  		struct dma_buf *dma_buf);
> +
> +extern struct drm_gem_object *drm_gem_prime_import_platform(
> +		struct drm_device *dev,
> +		struct dma_buf *dma_buf);
> +
>  extern int drm_gem_prime_fd_to_handle(struct drm_device *dev,
>  		struct drm_file *file_priv, int prime_fd, uint32_t *handle);
>  struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
> -- 
> 2.7.4
> 

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

[RFC PATCHv2 3/3] drm/vgem: Enable dmabuf import interfaces

[Laura Abbott]

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@redhat.com>
---
v2: Don't require vgem allocated buffers to existing in memory before importing.
---
 drivers/gpu/drm/vgem/vgem_drv.c | 133 +++++++++++++++++++++++++++++++---------
 drivers/gpu/drm/vgem/vgem_drv.h |   2 +
 2 files changed, 106 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
index 1b02e56..73a619a 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"
@@ -46,6 +49,12 @@ 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)
+		drm_free_large(vgem_obj->pages);
+
+	if (obj->import_attach)
+		drm_prime_gem_destroy(obj, vgem_obj->table);
+
 	drm_gem_object_release(obj);
 	kfree(vgem_obj);
 }
@@ -56,26 +65,48 @@ static int vgem_gem_fault(struct vm_fault *vmf)
 	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;
-
-	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;
+	int ret;
+	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;
+
+	if (obj->pages) {
+		get_page(obj->pages[page_offset]);
+		vmf->page = obj->pages[page_offset];
+		ret = 0;
+	} else {
+		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;
+		}
+
 	}
+	return ret;
 }
 
 static const struct vm_operations_struct vgem_gem_vm_ops = {
@@ -112,12 +143,8 @@ static void vgem_preclose(struct drm_device *dev, struct drm_file *file)
 	kfree(vfile);
 }
 
-/* ioctls */
-
-static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
-					      struct drm_file *file,
-					      unsigned int *handle,
-					      unsigned long size)
+static struct drm_vgem_gem_object *__vgem_gem_create(struct drm_device *dev,
+						unsigned long size)
 {
 	struct drm_vgem_gem_object *obj;
 	int ret;
@@ -127,8 +154,31 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
 		return ERR_PTR(-ENOMEM);
 
 	ret = drm_gem_object_init(dev, &obj->base, roundup(size, PAGE_SIZE));
-	if (ret)
-		goto err_free;
+	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,
+					      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);
 	drm_gem_object_unreference_unlocked(&obj->base);
@@ -137,9 +187,8 @@ static struct drm_gem_object *vgem_gem_create(struct drm_device *dev,
 
 	return &obj->base;
 
-err_free:
-	kfree(obj);
 err:
+	__vgem_gem_destroy(obj);
 	return ERR_PTR(ret);
 }
 
@@ -256,6 +305,29 @@ 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 *));
+	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 +386,11 @@ 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_platform,
 	.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..1aae014 100644
--- a/drivers/gpu/drm/vgem/vgem_drv.h
+++ b/drivers/gpu/drm/vgem/vgem_drv.h
@@ -43,6 +43,8 @@ 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;
 };
 
 int vgem_fence_open(struct vgem_file *file);
-- 
2.7.4

Re: [RFC PATCHv2 3/3] drm/vgem: Enable dmabuf import interfaces

[Chris Wilson]

On Wed, Apr 26, 2017 at 02:12:30PM -0700, Laura Abbott wrote:
> 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@redhat.com>
> ---
> v2: Don't require vgem allocated buffers to existing in memory before importing.
> ---
>  drivers/gpu/drm/vgem/vgem_drv.c | 133 +++++++++++++++++++++++++++++++---------
>  drivers/gpu/drm/vgem/vgem_drv.h |   2 +
>  2 files changed, 106 insertions(+), 29 deletions(-)
> 
> diff --git a/drivers/gpu/drm/vgem/vgem_drv.c b/drivers/gpu/drm/vgem/vgem_drv.c
> index 1b02e56..73a619a 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"
> @@ -46,6 +49,12 @@ 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)
> +		drm_free_large(vgem_obj->pages);

Just drm_free_large(vgem_obj->pages); NULL -> kfree() which is NULL safe.

The series lgtm, doesn't compromise on any of the existing tests.

All 3,
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

You could always get Joonas to nitpick over style...

> +
> +	if (obj->import_attach)
> +		drm_prime_gem_destroy(obj, vgem_obj->table);
> +
>  	drm_gem_object_release(obj);
>  	kfree(vgem_obj);
>  }
> @@ -56,26 +65,48 @@ static int vgem_gem_fault(struct vm_fault *vmf)
>  	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;
> -
> -	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;
> +	int ret;
> +	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;
> +
> +	if (obj->pages) {
> +		get_page(obj->pages[page_offset]);
> +		vmf->page = obj->pages[page_offset];
> +		ret = 0;
> +	} else {
> +		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;
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre

Re: [RFC PATCHv2 0/3] dma_buf import support for vgem

[Chris Wilson]

On Wed, Apr 26, 2017 at 02:12:27PM -0700, Laura Abbott wrote:
> Hi,
> 
> This is v2 of my proposal to add dma_buf import functions for vgem.
> Big changes from v1:
> 
> - A device is required for dma_buf attach to work. The existing vgem driver
> intentionally does not use one as it provides a good way to test the DRM
> framework. This approach instead puts a dummy platform device in the existing
> drm_device->platformdev field and uses that for attaching.
> - Native vgem buffers can still be faulted in a page at a time without
> requiring the entire buffer be resident in memory.
> 
> I'm still marking this as RFC as I haven't had a chance to finish
> a userspace test that can be integrated into igt.

Note, that it will be good to cc:intel-gfx@ so that our CI does run it
over the existing vgem tests.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre