From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
Add wrappers for the host vrings to support loose
coupling between the virtio device and driver.
A new struct vringh_config_ops with the functions
find_vrhs() and del_vrhs() is added to the virtio_device
struct. This enables virtio drivers to manage virtio
host rings without detailed knowledge of how the
vrings are created and deleted.
The function vringh_notify() is added so vringh clients
can notify the other side that buffers are added to the
used-ring.
Cc: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
---
Hi Rusty,
>It's weird that you conflate the host and guest ring sides in rpmsg, but
>that might make sense if they're really bound together.
Weird or not, CAIF-virtio is design to use guest rings for TX traffic,
and host rings for RX traffic. The motivation for this design is to allow
zero-copy in the data-path on the remote-device/modem.
Changes since v1:
- Moved find_vrhs() and del_vrhs() to a separate struct vringh_config_ops.
- Moved definition of struct vringh_config_ops into vringh.h
- Added vringh_config field to struct virtio_device
- Removed priv pointer field from struct vringh
There are a number of different ways to do this, let me know if you
want this changed in any way.
Thanks,
Sjur
include/linux/virtio.h | 3 +++
include/linux/vringh.h | 29 +++++++++++++++++++++++++++++
2 files changed, 32 insertions(+), 0 deletions(-)
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 00ccc40..5b71fc1 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -8,6 +8,7 @@
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>
+#include <linux/vringh.h>
/**
* virtqueue - a queue to register buffers for sending or receiving.
@@ -70,6 +71,7 @@ static inline unsigned int virtqueue_get_queue_index(struct virtqueue *vq)
* @dev: underlying device.
* @id: the device type identification (used to match it with a driver).
* @config: the configuration ops for this device.
+ * @vringh_config: configuration ops for host vrings.
* @vqs: the list of virtqueues for this device.
* @features: the features supported by both driver and device.
* @priv: private pointer for the driver's use.
@@ -79,6 +81,7 @@ struct virtio_device {
struct device dev;
struct virtio_device_id id;
struct virtio_config_ops *config;
+ struct vringh_config_ops *vringh_config;
struct list_head vqs;
/* Note that this is a Linux set_bit-style bitmap. */
unsigned long features[1];
diff --git a/include/linux/vringh.h b/include/linux/vringh.h
index ab41185..c7d9289 100644
--- a/include/linux/vringh.h
+++ b/include/linux/vringh.h
@@ -50,6 +50,28 @@ struct vringh {
/* The vring (note: it may contain user pointers!) */
struct vring vring;
+
+ /* The function to call to notify the guest about added buffers */
+ void (*notify)(struct vringh *);
+};
+
+/**
+ * struct vringh_config_ops - ops for creating a host vring from a virtio driver
+ * @find_vrhs: find the host vrings and instantiate them
+ * vdev: the virtio_device
+ * nhvrs: the number of host vrings to find
+ * hvrs: on success, includes new host vrings
+ * callbacks: array of driver callbacks, for each host vring
+ * include a NULL entry for vqs that do not need a callback
+ * Returns 0 on success or error status
+ * @del_vrhs: free the host vrings found by find_vrhs().
+ */
+struct virtio_device;
+typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
+struct vringh_config_ops {
+ int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs,
+ struct vringh *vrhs[], vrh_callback_t *callbacks[]);
+ void (*del_vrhs)(struct virtio_device *vdev);
};
/* The memory the vring can access, and what offset to apply. */
@@ -182,4 +204,11 @@ void vringh_notify_disable_kern(struct vringh *vrh);
int vringh_need_notify_kern(struct vringh *vrh);
+/* Notify the guest about buffers added to the used ring */
+static inline void vringh_notify(struct vringh *vrh)
+{
+ if (vrh->notify)
+ vrh->notify(vrh);
+}
+
#endif /* _LINUX_VRINGH_H */
--
1.7.5.4
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