Commit a0308938 authored by David Stevens's avatar David Stevens Committed by Gerd Hoffmann
Browse files

virtio: add dma-buf support for exported objects 



This change adds a new flavor of dma-bufs that can be used by virtio
drivers to share exported objects. A virtio dma-buf can be queried by
virtio drivers to obtain the UUID which identifies the underlying
exported object.

Signed-off-by: default avatarDavid Stevens <stevensd@chromium.org>
Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20200818071343.3461203-2-stevensd@chromium.org


Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent bbaac135

drivers/virtio/Makefile

+1 −1
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0

obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o

obj-$(CONFIG_VIRTIO) += virtio.o virtio_ring.o virtio_dma_buf.o

obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o

obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o

virtio_pci-y := virtio_pci_modern.o virtio_pci_common.o

drivers/virtio/virtio.c

+6 −0
Original line number Diff line number Diff line
@@ -357,6 +357,12 @@ int register_virtio_device(struct virtio_device *dev) 
}

EXPORT_SYMBOL_GPL(register_virtio_device);



bool is_virtio_device(struct device *dev)

{

	return dev->bus == &virtio_bus;

}

EXPORT_SYMBOL_GPL(is_virtio_device);



void unregister_virtio_device(struct virtio_device *dev)

{

	int index = dev->index; /* save for after device release */

drivers/virtio/virtio_dma_buf.c

0 → 100644
+85 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-or-later

/*

 * dma-bufs for virtio exported objects

 *

 * Copyright (C) 2020 Google, Inc.

 */



#include <linux/virtio_dma_buf.h>



/**

 * virtio_dma_buf_export - Creates a new dma-buf for a virtio exported object

 * @exp_info: [in] see dma_buf_export(). ops MUST refer to a dma_buf_ops

 *	struct embedded in a virtio_dma_buf_ops.

 *

 * This wraps dma_buf_export() to allow virtio drivers to create a dma-buf

 * for an virtio exported object that can be queried by other virtio drivers

 * for the object's UUID.

 */

struct dma_buf *virtio_dma_buf_export

	(const struct dma_buf_export_info *exp_info)

{

	const struct virtio_dma_buf_ops *virtio_ops =

		container_of(exp_info->ops,

			     const struct virtio_dma_buf_ops, ops);



	if (!exp_info->ops ||

	    exp_info->ops->attach != &virtio_dma_buf_attach ||

	    !virtio_ops->get_uuid) {

		return ERR_PTR(-EINVAL);

	}



	return dma_buf_export(exp_info);

}

EXPORT_SYMBOL(virtio_dma_buf_export);



/**

 * virtio_dma_buf_attach - mandatory attach callback for virtio dma-bufs

 */

int virtio_dma_buf_attach(struct dma_buf *dma_buf,

			  struct dma_buf_attachment *attach)

{

	int ret;

	const struct virtio_dma_buf_ops *ops =

		container_of(dma_buf->ops,

			     const struct virtio_dma_buf_ops, ops);



	if (ops->device_attach) {

		ret = ops->device_attach(dma_buf, attach);

		if (ret)

			return ret;

	}

	return 0;

}

EXPORT_SYMBOL(virtio_dma_buf_attach);



/**

 * is_virtio_dma_buf - returns true if the given dma-buf is a virtio dma-buf

 * @dma_buf: buffer to query

 */

bool is_virtio_dma_buf(struct dma_buf *dma_buf)

{

	return dma_buf->ops->attach == &virtio_dma_buf_attach;

}

EXPORT_SYMBOL(is_virtio_dma_buf);



/**

 * virtio_dma_buf_get_uuid - gets a virtio dma-buf's exported object's uuid

 * @dma_buf: [in] buffer to query

 * @uuid: [out] the uuid

 *

 * Returns: 0 on success, negative on failure.

 */

int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf,

			    uuid_t *uuid)

{

	const struct virtio_dma_buf_ops *ops =

		container_of(dma_buf->ops,

			     const struct virtio_dma_buf_ops, ops);



	if (!is_virtio_dma_buf(dma_buf))

		return -EINVAL;



	return ops->get_uuid(dma_buf, uuid);

}

EXPORT_SYMBOL(virtio_dma_buf_get_uuid);

include/linux/virtio.h

+1 −0
Original line number Diff line number Diff line
@@ -127,6 +127,7 @@ static inline struct virtio_device *dev_to_virtio(struct device *_dev) 
void virtio_add_status(struct virtio_device *dev, unsigned int status);

int register_virtio_device(struct virtio_device *dev);

void unregister_virtio_device(struct virtio_device *dev);

bool is_virtio_device(struct device *dev);



void virtio_break_device(struct virtio_device *dev);

include/linux/virtio_dma_buf.h

0 → 100644
+37 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * dma-bufs for virtio exported objects

 *

 * Copyright (C) 2020 Google, Inc.

 */



#ifndef _LINUX_VIRTIO_DMA_BUF_H

#define _LINUX_VIRTIO_DMA_BUF_H



#include <linux/dma-buf.h>

#include <linux/uuid.h>

#include <linux/virtio.h>



/**

 * struct virtio_dma_buf_ops - operations possible on exported object dma-buf

 * @ops: the base dma_buf_ops. ops.attach MUST be virtio_dma_buf_attach.

 * @device_attach: [optional] callback invoked by virtio_dma_buf_attach during

 *		   all attach operations.

 * @get_uid: [required] callback to get the uuid of the exported object.

 */

struct virtio_dma_buf_ops {

	struct dma_buf_ops ops;

	int (*device_attach)(struct dma_buf *dma_buf,

			     struct dma_buf_attachment *attach);

	int (*get_uuid)(struct dma_buf *dma_buf, uuid_t *uuid);

};



int virtio_dma_buf_attach(struct dma_buf *dma_buf,

			  struct dma_buf_attachment *attach);



struct dma_buf *virtio_dma_buf_export

	(const struct dma_buf_export_info *exp_info);

bool is_virtio_dma_buf(struct dma_buf *dma_buf);

int virtio_dma_buf_get_uuid(struct dma_buf *dma_buf, uuid_t *uuid);



#endif /* _LINUX_VIRTIO_DMA_BUF_H */