vhost-blk: recover ring base when reconnect

This patch is for packed ring and recover the ring
base when vhost target reconnect to QEMU.

Change-Id: I73f791b4a55adf9834112afd7dd7bb26c75a135d
Signed-off-by: Jin Yu <jin.yu@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4128
Community-CI: Broadcom CI
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Shuhei Matsumoto <shuhei.matsumoto.xt@hitachi.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>

lib/vhost/vhost.c

@@ -42,6 +42,8 @@
 #include "spdk/vhost.h"
 #include "vhost_internal.h"
 
+bool g_packed_ring_recovery = false;
+
 static struct spdk_cpuset g_vhost_core_mask;
 
 /* Path to folder where character device will be created. Can be set by user. */
@@ -1340,6 +1342,19 @@ vhost_start_device_cb(int vid)
 		}
 
 		if (packed_ring) {
+			/* Use the inflight mem to restore the last_avail_idx and last_used_idx.
+			 * When the vring format is packed, there is no used_idx in the
+			 * used ring, so VM can't resend the used_idx to VHOST when reconnect.
+			 * QEMU version 5.2.0 supports the packed inflight before that it only
+			 * supports split ring inflight because it doesn't send negotiated features
+			 * before get inflight fd. Users can use RPC to enable this function.
+			 */
+			if (spdk_unlikely(g_packed_ring_recovery)) {
+				rte_vhost_get_vring_base_from_inflight(vsession->vid, i,
+								       &q->last_avail_idx,
+								       &q->last_used_idx);
+			}
+
 			/* Packed virtqueues support up to 2^15 entries each
 			 * so left one bit can be used as wrap counter.
 			 */

lib/vhost/vhost_internal.h

@@ -45,6 +45,8 @@
 #include "spdk/rpc.h"
 #include "spdk/config.h"
 
+extern bool g_packed_ring_recovery;
+
 #define SPDK_VHOST_MAX_VQUEUES	256
 #define SPDK_VHOST_MAX_VQ_SIZE	1024
 

lib/vhost/vhost_rpc.c

@@ -237,6 +237,7 @@ struct rpc_vhost_blk_ctrlr {
 	char *cpumask;
 	bool readonly;
 	bool packed_ring;
+	bool packed_ring_recovery;
 };
 
 static const struct spdk_json_object_decoder rpc_construct_vhost_blk_ctrlr[] = {
@@ -245,6 +246,7 @@ static const struct spdk_json_object_decoder rpc_construct_vhost_blk_ctrlr[] = {
 	{"cpumask", offsetof(struct rpc_vhost_blk_ctrlr, cpumask), spdk_json_decode_string, true},
 	{"readonly", offsetof(struct rpc_vhost_blk_ctrlr, readonly), spdk_json_decode_bool, true},
 	{"packed_ring", offsetof(struct rpc_vhost_blk_ctrlr, packed_ring), spdk_json_decode_bool, true},
+	{"packed_ring_recovery", offsetof(struct rpc_vhost_blk_ctrlr, packed_ring_recovery), spdk_json_decode_bool, true},
 };
 
 static void
@@ -270,6 +272,8 @@ rpc_vhost_create_blk_controller(struct spdk_jsonrpc_request *request,
 		goto invalid;
 	}
 
+	g_packed_ring_recovery = req.packed_ring_recovery;
+
 	rc = spdk_vhost_blk_construct(req.ctrlr, req.cpumask, req.dev_name,
 				      req.readonly, req.packed_ring);
 	if (rc < 0) {

scripts/rpc.py

@@ -2202,7 +2202,8 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
                                               dev_name=args.dev_name,
                                               cpumask=args.cpumask,
                                               readonly=args.readonly,
-                                              packed_ring=args.packed_ring)
+                                              packed_ring=args.packed_ring,
+                                              packed_ring_recovery=args.packed_ring_recovery)
 
     p = subparsers.add_parser('vhost_create_blk_controller',
                               aliases=['construct_vhost_blk_controller'],
@@ -2212,6 +2213,7 @@ Format: 'user:u1 secret:s1 muser:mu1 msecret:ms1,user:u2 secret:s2 muser:mu2 mse
     p.add_argument('--cpumask', help='cpu mask for this controller')
     p.add_argument("-r", "--readonly", action='store_true', help='Set controller as read-only')
     p.add_argument("-p", "--packed_ring", action='store_true', help='Set controller as packed ring supported')
+    p.add_argument("-l", "--packed_ring_recovery", action='store_true', help='Enable packed ring live reocvery')
     p.set_defaults(func=vhost_create_blk_controller)
 
     def vhost_get_controllers(args):

scripts/rpc/vhost.py

@@ -63,7 +63,7 @@ def vhost_scsi_controller_remove_target(client, ctrlr, scsi_target_num):
 
 
 @deprecated_alias('construct_vhost_blk_controller')
-def vhost_create_blk_controller(client, ctrlr, dev_name, cpumask=None, readonly=None, packed_ring=None):
+def vhost_create_blk_controller(client, ctrlr, dev_name, cpumask=None, readonly=None, packed_ring=None, packed_ring_recovery=None):
     """Create vhost BLK controller.
     Args:
         ctrlr: controller name
@@ -71,6 +71,7 @@ def vhost_create_blk_controller(client, ctrlr, dev_name, cpumask=None, readonly=
         cpumask: cpu mask for this controller
         readonly: set controller as read-only
         packed_ring: support controller packed_ring
+        packed_ring_recovery: enable packed ring live recovery
     """
     params = {
         'ctrlr': ctrlr,
@@ -82,6 +83,8 @@ def vhost_create_blk_controller(client, ctrlr, dev_name, cpumask=None, readonly=
         params['readonly'] = readonly
     if packed_ring:
         params['packed_ring'] = packed_ring
+    if packed_ring_recovery:
+        params['packed_ring_recovery'] = packed_ring_recovery
     return client.call('vhost_create_blk_controller', params)
 
 

test/unit/lib/vhost/vhost.c/vhost_ut.c

@@ -86,6 +86,8 @@ DEFINE_STUB(vhost_get_negotiated_features, int,
 	    (int vid, uint64_t *negotiated_features), 0);
 DEFINE_STUB(rte_vhost_get_vhost_ring_inflight, int,
 	    (int vid, uint16_t vring_idx, struct rte_vhost_ring_inflight *vring), 0);
+DEFINE_STUB(rte_vhost_get_vring_base_from_inflight, int,
+	    (int vid, uint16_t queue_id, uint16_t *last_avail_idx, uint16_t *last_used_idx), 0);
 DEFINE_STUB(vhost_get_mem_table, int, (int vid, struct rte_vhost_memory **mem), 0);
 
 void *