vmd: method for forcing a rescan

Added a new RPC, vmd_rescan, that forces the VMD driver to do a rescan
of all devices behind the VMD.  A device that was previously removed via
spdk_vmd_remove_device() will be found again during vmd_rescan.

Signed-off-by: Konrad Sztyber <konrad.sztyber@intel.com>
Change-Id: Ide87eb44c1d6d524234820dc07c78ba5b8bcd3ad
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13958
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tom Nabarro <tom.nabarro@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>

doc/jsonrpc.md

@@ -10030,6 +10030,40 @@ Example response:
 }
 ~~~
 
+### vmd_rescan {#rpc_vmd_rescan}
+
+Force a rescan of the devices behind VMD.
+
+### Parameters
+
+This method has no parameters.
+
+#### Response
+
+The response is the number of new devices found.
+
+### Example
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "method": "vmd_rescan",
+  "id": 1
+}
+~~~
+
+Example response:
+
+~~~json
+{
+  "jsonrpc": "2.0",
+  "id": 1,
+  "result": {
+    "count": 1
+  }
+}
+~~~
+
 ### spdk_get_version {#rpc_spdk_get_version}
 
 Get the version info of the running SPDK application.

include/spdk/vmd.h

@@ -90,6 +90,14 @@ int spdk_vmd_hotplug_monitor(void);
  */
 int spdk_vmd_remove_device(const struct spdk_pci_addr *addr);
 
+/**
+ * Forces a rescan of the devices behind the VMD.  If a device was previously removed through
+ * spdk_vmd_remove_device() this will cause it to be reattached.
+ *
+ * \return number of new devices found during scanning or negative errno on failure.
+ */
+int spdk_vmd_rescan(void);
+
 #ifdef __cplusplus
 }
 #endif

lib/vmd/spdk_vmd.map

@@ -9,6 +9,7 @@
 	spdk_vmd_get_led_state;
 	spdk_vmd_hotplug_monitor;
 	spdk_vmd_remove_device;
+	spdk_vmd_rescan;
 
 	local: *;
 };

lib/vmd/vmd.c

@@ -1435,6 +1435,22 @@ spdk_vmd_remove_device(const struct spdk_pci_addr *addr)
 	return 0;
 }
 
+int
+spdk_vmd_rescan(void)
+{
+	struct vmd_pci_bus *bus;
+	uint32_t i;
+	int rc = 0;
+
+	for (i = 0; i < g_vmd_container.count; ++i) {
+		TAILQ_FOREACH(bus, &g_vmd_container.vmd[i].bus_list, tailq) {
+			rc += vmd_scan_single_bus(bus, bus->self, true);
+		}
+	}
+
+	return rc;
+}
+
 static int
 vmd_attach_device(const struct spdk_pci_addr *addr)
 {

module/event/subsystems/vmd/vmd_rpc.c

@@ -69,3 +69,28 @@ out:
 	free(req.addr);
 }
 SPDK_RPC_REGISTER("vmd_remove_device", rpc_vmd_remove_device, SPDK_RPC_RUNTIME)
+
+static void
+rpc_vmd_rescan(struct spdk_jsonrpc_request *request, const struct spdk_json_val *params)
+{
+	struct spdk_json_write_ctx *w;
+	int rc;
+
+	if (!vmd_subsystem_is_enabled()) {
+		spdk_jsonrpc_send_error_response(request, -EPERM, "VMD subsystem is disabled");
+		return;
+	}
+
+	rc = spdk_vmd_rescan();
+	if (rc < 0) {
+		spdk_jsonrpc_send_error_response(request, rc, spdk_strerror(-rc));
+		return;
+	}
+
+	w = spdk_jsonrpc_begin_result(request);
+	spdk_json_write_object_begin(w);
+	spdk_json_write_named_uint32(w, "count", (uint32_t)rc);
+	spdk_json_write_object_end(w);
+	spdk_jsonrpc_end_result(request, w);
+}
+SPDK_RPC_REGISTER("vmd_rescan", rpc_vmd_rescan, SPDK_RPC_RUNTIME)

python/spdk/rpc/vmd.py

@@ -10,3 +10,8 @@ def vmd_enable(client):
 def vmd_remove_device(client, addr):
     """Remove a device behind VMD"""
     return client.call('vmd_remove_device', {'addr': addr})
+
+
+def vmd_rescan(client):
+    """Force a rescan of the devices behind VMD"""
+    return client.call('vmd_rescan')

scripts/rpc.py

@@ -2080,6 +2080,12 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.add_argument('addr', help='Address of the device to remove', type=str)
     p.set_defaults(func=vmd_remove_device)
 
+    def vmd_rescan(args):
+        print_dict(rpc.vmd.vmd_rescan(args.client))
+
+    p = subparsers.add_parser('vmd_rescan', help='Force a rescan of the devices behind VMD')
+    p.set_defaults(func=vmd_rescan)
+
     # nbd
     def nbd_start_disk(args):
         print(rpc.nbd.nbd_start_disk(args.client,