[PATCH 4/4] Drivers: hv: vmbus: add numa_node to sysfs

[kys]

From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>

Being able to find the numa_node for a device is useful for userspace
drivers (DPDK) and also for diagnosing performance issues.  This makes
vmbus similar to pci.

Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
---
 Documentation/ABI/stable/sysfs-bus-vmbus |  7 +++++++
 drivers/hv/vmbus_drv.c                   | 17 +++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/Documentation/ABI/stable/sysfs-bus-vmbus b/Documentation/ABI/stable/sysfs-bus-vmbus
index 3eaffbb2d468..3fed8fdb873d 100644
--- a/Documentation/ABI/stable/sysfs-bus-vmbus
+++ b/Documentation/ABI/stable/sysfs-bus-vmbus
@@ -42,6 +42,13 @@ Contact:	K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
 Description:	The 16 bit vendor ID of the device
 Users:		tools/hv/lsvmbus and user level RDMA libraries
 
+What:		/sys/bus/vmbus/devices/<UUID>/numa_node
+Date:		Jul 2018
+KernelVersion:	4.19
+Contact:	Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
+Description:	This NUMA node to which the VMBUS device is
+		attached, or -1 if the node is unknown.
+
 What:		/sys/bus/vmbus/devices/<UUID>/channels/<N>
 Date:		September. 2017
 KernelVersion:	4.14
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index db145e1a7049..b1b548a21f91 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -210,6 +210,20 @@ static ssize_t modalias_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(modalias);
 
+#ifdef CONFIG_NUMA
+static ssize_t numa_node_show(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+
+	if (!hv_dev->channel)
+		return -ENODEV;
+
+	return sprintf(buf, "%d\n", hv_dev->channel->numa_node);
+}
+static DEVICE_ATTR_RO(numa_node);
+#endif
+
 static ssize_t server_monitor_pending_show(struct device *dev,
 					   struct device_attribute *dev_attr,
 					   char *buf)
@@ -492,6 +506,9 @@ static struct attribute *vmbus_dev_attrs[] = {
 	&dev_attr_class_id.attr,
 	&dev_attr_device_id.attr,
 	&dev_attr_modalias.attr,
+#ifdef CONFIG_NUMA
+	&dev_attr_numa_node.attr,
+#endif
 	&dev_attr_server_monitor_pending.attr,
 	&dev_attr_client_monitor_pending.attr,
 	&dev_attr_server_monitor_latency.attr,
-- 
2.17.1