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authorDavid Stevens <stevensd@chromium.org>2020-08-18 16:13:41 +0900
committerGerd Hoffmann <kraxel@redhat.com>2020-08-18 10:01:44 +0200
commita0308938ec81cd0dca9d75833ec0dd1b8708917e (patch)
treea7a8c3421f26b9ce09dd86ddc1004813793c2a25 /drivers/virtio/virtio_dma_buf.c
parentbbaac1354cc98415e5b4c3830d796c583ca71907 (diff)
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: David Stevens <stevensd@chromium.org> Acked-by: Michael S. Tsirkin <mst@redhat.com> Link: http://patchwork.freedesktop.org/patch/msgid/20200818071343.3461203-2-stevensd@chromium.org Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Diffstat (limited to 'drivers/virtio/virtio_dma_buf.c')
-rw-r--r--drivers/virtio/virtio_dma_buf.c85
1 files changed, 85 insertions, 0 deletions
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);