[RFC v2 07/13] vduse: support get/set virtqueue state

[Xie Yongji <xieyongji@bytedance.com>]

This patch makes vhost-vdpa bus driver can get/set virtqueue
state from userspace VDUSE process.

Signed-off-by: Xie Yongji <xieyongji@bytedance.com>
---
 Documentation/driver-api/vduse.rst |  4 +++
 drivers/vdpa/vdpa_user/vduse_dev.c | 54 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vduse.h         |  9 +++++++
 3 files changed, 67 insertions(+)

diff --git a/Documentation/driver-api/vduse.rst b/Documentation/driver-api/vduse.rst
index da9b3040f20a..623f7b040ccf 100644
--- a/Documentation/driver-api/vduse.rst
+++ b/Documentation/driver-api/vduse.rst
@@ -30,6 +30,10 @@ The following types of messages are provided by the VDUSE framework now:
 
 - VDUSE_GET_VQ_READY: Get ready status of virtqueue
 
+- VDUSE_SET_VQ_STATE: Set the state (last_avail_idx) for virtqueue
+
+- VDUSE_GET_VQ_STATE: Get the state (last_avail_idx) for virtqueue
+
 - VDUSE_SET_FEATURES: Set virtio features supported by the driver
 
 - VDUSE_GET_FEATURES: Get virtio features supported by the device
diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c b/drivers/vdpa/vdpa_user/vduse_dev.c
index 4a869b9698ef..b974333ed4e9 100644
--- a/drivers/vdpa/vdpa_user/vduse_dev.c
+++ b/drivers/vdpa/vdpa_user/vduse_dev.c
@@ -291,6 +291,40 @@ static bool vduse_dev_get_vq_ready(struct vduse_dev *dev,
 	return ready;
 }
 
+static int vduse_dev_get_vq_state(struct vduse_dev *dev,
+				struct vduse_virtqueue *vq,
+				struct vdpa_vq_state *state)
+{
+	struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_GET_VQ_STATE);
+	int ret;
+
+	msg->req.size = sizeof(struct vduse_vq_state);
+	msg->req.vq_state.index = vq->index;
+
+	ret = vduse_dev_msg_sync(dev, msg);
+	state->avail_index = msg->resp.vq_state.avail_idx;
+	vduse_dev_msg_put(msg);
+
+	return ret;
+}
+
+static int vduse_dev_set_vq_state(struct vduse_dev *dev,
+				struct vduse_virtqueue *vq,
+				const struct vdpa_vq_state *state)
+{
+	struct vduse_dev_msg *msg = vduse_dev_new_msg(dev, VDUSE_SET_VQ_STATE);
+	int ret;
+
+	msg->req.size = sizeof(struct vduse_vq_state);
+	msg->req.vq_state.index = vq->index;
+	msg->req.vq_state.avail_idx = state->avail_index;
+
+	ret = vduse_dev_msg_sync(dev, msg);
+	vduse_dev_msg_put(msg);
+
+	return ret;
+}
+
 static ssize_t vduse_dev_read_iter(struct kiocb *iocb, struct iov_iter *to)
 {
 	struct file *file = iocb->ki_filp;
@@ -431,6 +465,24 @@ static bool vduse_vdpa_get_vq_ready(struct vdpa_device *vdpa, u16 idx)
 	return vq->ready;
 }
 
+static int vduse_vdpa_set_vq_state(struct vdpa_device *vdpa, u16 idx,
+				const struct vdpa_vq_state *state)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	return vduse_dev_set_vq_state(dev, vq, state);
+}
+
+static int vduse_vdpa_get_vq_state(struct vdpa_device *vdpa, u16 idx,
+				struct vdpa_vq_state *state)
+{
+	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
+	struct vduse_virtqueue *vq = &dev->vqs[idx];
+
+	return vduse_dev_get_vq_state(dev, vq, state);
+}
+
 static u32 vduse_vdpa_get_vq_align(struct vdpa_device *vdpa)
 {
 	struct vduse_dev *dev = vdpa_to_vduse(vdpa);
@@ -532,6 +584,8 @@ static const struct vdpa_config_ops vduse_vdpa_config_ops = {
 	.set_vq_num             = vduse_vdpa_set_vq_num,
 	.set_vq_ready		= vduse_vdpa_set_vq_ready,
 	.get_vq_ready		= vduse_vdpa_get_vq_ready,
+	.set_vq_state		= vduse_vdpa_set_vq_state,
+	.get_vq_state		= vduse_vdpa_get_vq_state,
 	.get_vq_align		= vduse_vdpa_get_vq_align,
 	.get_features		= vduse_vdpa_get_features,
 	.set_features		= vduse_vdpa_set_features,
diff --git a/include/uapi/linux/vduse.h b/include/uapi/linux/vduse.h
index f8579abdaa3b..873305dfd93f 100644
--- a/include/uapi/linux/vduse.h
+++ b/include/uapi/linux/vduse.h
@@ -13,6 +13,8 @@ enum vduse_req_type {
 	VDUSE_SET_VQ_ADDR,
 	VDUSE_SET_VQ_READY,
 	VDUSE_GET_VQ_READY,
+	VDUSE_SET_VQ_STATE,
+	VDUSE_GET_VQ_STATE,
 	VDUSE_SET_FEATURES,
 	VDUSE_GET_FEATURES,
 	VDUSE_SET_STATUS,
@@ -38,6 +40,11 @@ struct vduse_vq_ready {
 	__u8 ready;
 };
 
+struct vduse_vq_state {
+	__u32 index;
+	__u16 avail_idx;
+};
+
 struct vduse_dev_config_data {
 	__u32 offset;
 	__u32 len;
@@ -53,6 +60,7 @@ struct vduse_dev_request {
 		struct vduse_vq_num vq_num; /* virtqueue num */
 		struct vduse_vq_addr vq_addr; /* virtqueue address */
 		struct vduse_vq_ready vq_ready; /* virtqueue ready status */
+		struct vduse_vq_state vq_state; /* virtqueue state */
 		struct vduse_dev_config_data config; /* virtio device config space */
 		__u64 features; /* virtio features */
 		__u8 status; /* device status */
@@ -64,6 +72,7 @@ struct vduse_dev_response {
 	__s32 result; /* the result of request */
 	union {
 		struct vduse_vq_ready vq_ready; /* virtqueue ready status */
+		struct vduse_vq_state vq_state; /* virtqueue state */
 		struct vduse_dev_config_data config; /* virtio device config space */
 		__u64 features; /* virtio features */
 		__u8 status; /* device status */
-- 
2.11.0