RE: [PATH v1 1/2] vdpa: Add support for querying vendor statistics

From: Eli Cohen <redacted>
Sent: Wednesday, November 24, 2021 10:26 PM

Add support for querying virtqueue statistics. Supported statistics are:

received_desc - number of descriptors received for the virtqueue
completed_desc - number of descriptors completed for the virtqueue

A descriptors using indirect buffers is still counted as 1. In addition, N chained
descriptors are counted correctly N times as one would expect.

A new callback was added to vdpa_config_ops which provides the means for
the vdpa driver to return statistics results.

The interface allows for reading all the supported virtqueues, including the
control virtqueue if it exists, by returning the next queue index to query.

Examples:
1. Read statisitics for the virtqueue at index 1 $ vdpa dev vstats show vdpa-a
qidx 0
vdpa-a:
qidx 0 rx received_desc 256 completed_desc 9

2. Read statisitics for all the virtqueues $ vdpa dev vstats show vdpa-a
vdpa-a:
qidx 0 rx received_desc 256 completed_desc 9 qidx 1 tx received_desc 21
completed_desc 21 qidx 2 ctrl received_desc 0 completed_desc 0

Signed-off-by: Eli Cohen <redacted>
---
v0 -> v1:
Emphasize that we're dealing with vendor specific counters.
Terminate query loop on error

 drivers/vdpa/vdpa.c       | 144 ++++++++++++++++++++++++++++++++++++++
 include/linux/vdpa.h      |  10 +++
 include/uapi/linux/vdpa.h |   9 +++
 3 files changed, 163 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index

7332a74a4b00..da658c80ff2a 100644

--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c

@@ -781,6 +781,90 @@ vdpa_dev_config_fill(struct vdpa_device *vdev, struct

sk_buff *msg, u32 portid,
 	return err;
 }

+static int vdpa_fill_stats_rec(struct vdpa_device *vdev, struct sk_buff
+*msg, u16 *index) {
+	struct vdpa_vq_stats stats;

+sk_buff *msg, u16 index) {
+	int err;
+
+	if (!vdev->config->get_vq_stats)
+		return -EOPNOTSUPP;
+
+	if (index != VDPA_INVAL_QUEUE_INDEX) {
+		err = vdpa_fill_stats_rec(vdev, msg, &index);
+		if (err)
+			return err;
+	} else {
+		index = 0;
+		do {
+			err = vdpa_fill_stats_rec(vdev, msg, &index);
+			if (err)
+				return err;
+		} while (index != VDPA_INVAL_QUEUE_INDEX);
+	}
+
+	return 0;
+}
+
+static int vdpa_dev_stats_fill(struct vdpa_device *vdev, struct sk_buff *msg,
u32 portid,
+			       u32 seq, int flags, u16 index) {
+	u32 device_id;
+	void *hdr;
+	int err;
+
+	hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags,
+			  VDPA_CMD_DEV_VSTATS_GET);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (nla_put_string(msg, VDPA_ATTR_DEV_NAME, dev_name(&vdev-

quoted

dev))) {

+		err = -EMSGSIZE;
+		goto undo_msg;
+	}
+
+	device_id = vdev->config->get_device_id(vdev);
+	if (nla_put_u32(msg, VDPA_ATTR_DEV_ID, device_id)) {
+		err = -EMSGSIZE;
+		goto undo_msg;
+	}
+
+	err = vdpa_dev_net_stats_fill(vdev, msg, index);
+
+	genlmsg_end(msg, hdr);
+
+	return err;
+
+undo_msg:
+	genlmsg_cancel(msg, hdr);
+	return err;
+}
+
 static int vdpa_nl_cmd_dev_config_get_doit(struct sk_buff *skb, struct
genl_info *info)  {
 	struct vdpa_device *vdev;

@@ -862,6 +946,59 @@ vdpa_nl_cmd_dev_config_get_dumpit(struct sk_buff

*msg, struct netlink_callback *
 	return msg->len;
 }

+static int vdpa_nl_cmd_dev_stats_get_doit(struct sk_buff *skb,
+					  struct genl_info *info)
+{
+	struct vdpa_device *vdev;
+	struct sk_buff *msg;
+	const char *devname;
+	struct device *dev;
+	u16 index = -1;
+	int err;
+
+	if (!info->attrs[VDPA_ATTR_DEV_NAME])
+		return -EINVAL;
+
+	if (info->attrs[VDPA_ATTR_DEV_QUEUE_INDEX])
+		index = nla_get_u16(info-

quoted

attrs[VDPA_ATTR_DEV_QUEUE_INDEX]);

+
+	devname = nla_data(info->attrs[VDPA_ATTR_DEV_NAME]);
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	mutex_lock(&vdpa_dev_mutex);
+	dev = bus_find_device(&vdpa_bus, NULL, devname,
vdpa_name_match);
+	if (!dev) {
+		NL_SET_ERR_MSG_MOD(info->extack, "device not found");
+		err = -ENODEV;
+		goto dev_err;
+	}
+	vdev = container_of(dev, struct vdpa_device, dev);
+	if (!vdev->mdev) {
+		NL_SET_ERR_MSG_MOD(info->extack, "unmanaged vdpa
device");
+		err = -EINVAL;
+		goto mdev_err;
+	}
+	err = vdpa_dev_stats_fill(vdev, msg, info->snd_portid, info->snd_seq,
0, index);