Guenter Roeck
2020-Sep-10 15:06 UTC
[PATCH v7 1/3] virtio: add dma-buf support for exported objects
On Tue, Aug 18, 2020 at 04:13:41PM +0900, David Stevens wrote:> 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: David Stevens <stevensd at chromium.org>This makes VIRTIO dependent on DMA_SHARED_BUFFER. That means "select DMA_SHARED_BUFFER" will have to be added to "config VIRTIO". Guenter> --- > drivers/virtio/Makefile | 2 +- > drivers/virtio/virtio.c | 6 +++ > drivers/virtio/virtio_dma_buf.c | 85 +++++++++++++++++++++++++++++++++ > include/linux/virtio.h | 1 + > include/linux/virtio_dma_buf.h | 37 ++++++++++++++ > 5 files changed, 130 insertions(+), 1 deletion(-) > create mode 100644 drivers/virtio/virtio_dma_buf.c > create mode 100644 include/linux/virtio_dma_buf.h > > diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile > index 29a1386ecc03..ecdae5b596de 100644 > --- a/drivers/virtio/Makefile > +++ b/drivers/virtio/Makefile > @@ -1,5 +1,5 @@ > # 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 > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index a977e32a88f2..5d46f0ded92d 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -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 */ > diff --git a/drivers/virtio/virtio_dma_buf.c b/drivers/virtio/virtio_dma_buf.c > new file mode 100644 > index 000000000000..45d6e8647dcf > --- /dev/null > +++ b/drivers/virtio/virtio_dma_buf.c > @@ -0,0 +1,85 @@ > +// 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); > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 15f906e4a748..9397e25616c4 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -128,6 +128,7 @@ 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); > > diff --git a/include/linux/virtio_dma_buf.h b/include/linux/virtio_dma_buf.h > new file mode 100644 > index 000000000000..a2fdf217ac62 > --- /dev/null > +++ b/include/linux/virtio_dma_buf.h > @@ -0,0 +1,37 @@ > +/* 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 */