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@chromium.org --- drivers/virtio/Makefile | 2 +- drivers/virtio/virtio.c | 6 ++ drivers/virtio/virtio_dma_buf.c | 97 +++++++++++++++++++++++++++++++++ include/linux/virtio.h | 1 + include/linux/virtio_dma_buf.h | 62 +++++++++++++++++++++ 5 files changed, 167 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 3a2b5c5dcf46..0ad30f4cdb9f 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..1f7e2d50b189 --- /dev/null +++ b/drivers/virtio/virtio_dma_buf.c @@ -0,0 +1,97 @@ +// 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 + * + * 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 virtio_dma_buf_export_info *virtio_exp_info) +{ + struct dma_buf_export_info exp_info; + + if (!virtio_exp_info->ops + || virtio_exp_info->ops->ops.attach != &virtio_dma_buf_attach + || !virtio_exp_info->ops->get_uuid) { + return ERR_PTR(-EINVAL); + } + + exp_info.exp_name = virtio_exp_info->exp_name; + exp_info.owner = virtio_exp_info->owner; + exp_info.ops = &virtio_exp_info->ops->ops; + exp_info.size = virtio_exp_info->size; + exp_info.flags = virtio_exp_info->flags; + exp_info.resv = virtio_exp_info->resv; + exp_info.priv = virtio_exp_info->priv; + BUILD_BUG_ON(sizeof(struct virtio_dma_buf_export_info) + != sizeof(struct dma_buf_export_info)); + + 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->virtio_attach && is_virtio_device(attach->dev)) { + ret = ops->virtio_attach(dma_buf, attach); + if (ret) + return ret; + } + + 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); + +/** + * get_virtio_dma_buf_uuid - gets the uuid for the dma-buf's exported object + * @dma_buf: [in] buffer to query + * @uuid: [out] the uuid + * + * This function should only be called on dma_bufs attached to a virtio device. + * + * Returns: 0 on success, negative on failure. + */ +int get_virtio_dma_buf_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(get_virtio_dma_buf_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..d841a9115876 --- /dev/null +++ b/include/linux/virtio_dma_buf.h @@ -0,0 +1,62 @@ +/* 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. + * @virtio_attach: [optional] callback invoked by virtio_dma_buf_attach if + * the attaching device is a virtio device. + * @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 (*virtio_attach)(struct dma_buf *dma_buf, + struct dma_buf_attachment *attach); + int (*device_attach)(struct dma_buf *dma_buf, + struct dma_buf_attachment *attach); + int (*get_uuid)(struct dma_buf *dma_buf, uuid_t *uuid); +}; + +/** + * struct virtio_dma_buf_export_info - see struct dma_buf_export_info + */ +struct virtio_dma_buf_export_info { + const char *exp_name; + struct module *owner; + const struct virtio_dma_buf_ops *ops; + size_t size; + int flags; + struct dma_resv *resv; + void *priv; +}; + +/** + * DEFINE_VIRTIO_DMA_BUF_EXPORT_INFO - helper macro for exporters + */ +#define DEFINE_VIRTIO_DMA_BUF_EXPORT_INFO(name) \ + struct virtio_dma_buf_export_info name = { \ + .exp_name = KBUILD_MODNAME, \ + .owner = THIS_MODULE } + +int virtio_dma_buf_attach(struct dma_buf *dma_buf, + struct dma_buf_attachment *attach); + +struct dma_buf *virtio_dma_buf_export( + const struct virtio_dma_buf_export_info *virtio_exp_info); +bool is_virtio_dma_buf(struct dma_buf *dma_buf); +int get_virtio_dma_buf_uuid(struct dma_buf *dma_buf, uuid_t *uuid); + +#endif /* _LINUX_VIRTIO_DMA_BUF_H */