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2023-12-09 b22da3d8526a935aa31e086e63f60ff3246cb61c 
 kernel/drivers/block/xen-blkback/xenbus.c
....@@ -1,16 +1,8 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*  Xenbus code for blkif backend
23     Copyright (C) 2005 Rusty Russell <rusty@rustcorp.com.au>
34     Copyright (C) 2005 XenSource Ltd
45 
5
-    This program is free software; you can redistribute it and/or modify
6
-    it under the terms of the GNU General Public License as published by
7
-    the Free Software Foundation; either version 2 of the License, or
8
-    (at your option) any later version.
9
-
10
-    This program is distributed in the hope that it will be useful,
11
-    but WITHOUT ANY WARRANTY; without even the implied warranty of
12
-    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13
-    GNU General Public License for more details.
146 
157 */
168 
....@@ -152,8 +144,7 @@
152144 		INIT_LIST_HEAD(&ring->pending_free);
153145 		INIT_LIST_HEAD(&ring->persistent_purge_list);
154146 		INIT_WORK(&ring->persistent_purge_work, xen_blkbk_unmap_purged_grants);
155
-		spin_lock_init(&ring->free_pages_lock);
156
-		INIT_LIST_HEAD(&ring->free_pages);
147
+		gnttab_page_cache_init(&ring->free_pages);
157148 
158149 		spin_lock_init(&ring->pending_free_lock);
159150 		init_waitqueue_head(&ring->pending_free_wq);
....@@ -165,6 +156,11 @@
165156 
166157 	return 0;
167158 }
159
+
160
+/* Enable the persistent grants feature. */
161
+static bool feature_persistent = true;
162
+module_param(feature_persistent, bool, 0644);
163
+MODULE_PARM_DESC(feature_persistent, "Enables the persistent grants feature");
168164 
169165 static struct xen_blkif *xen_blkif_alloc(domid_t domid)
170166 {
....@@ -198,6 +194,9 @@
198194 {
199195 	int err;
200196 	struct xen_blkif *blkif = ring->blkif;
197
+	const struct blkif_common_sring *sring_common;
198
+	RING_IDX rsp_prod, req_prod;
199
+	unsigned int size;
201200 
202201 	/* Already connected through? */
203202 	if (ring->irq)
....@@ -208,45 +207,61 @@
208207 	if (err < 0)
209208 		return err;
210209 
210
+	sring_common = (struct blkif_common_sring *)ring->blk_ring;
211
+	rsp_prod = READ_ONCE(sring_common->rsp_prod);
212
+	req_prod = READ_ONCE(sring_common->req_prod);
213
+
211214 	switch (blkif->blk_protocol) {
212215 	case BLKIF_PROTOCOL_NATIVE:
213216 	{
214
-		struct blkif_sring *sring;
215
-		sring = (struct blkif_sring *)ring->blk_ring;
216
-		BACK_RING_INIT(&ring->blk_rings.native, sring,
217
-			       XEN_PAGE_SIZE * nr_grefs);
217
+		struct blkif_sring *sring_native =
218
+			(struct blkif_sring *)ring->blk_ring;
219
+
220
+		BACK_RING_ATTACH(&ring->blk_rings.native, sring_native,
221
+				 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
222
+		size = __RING_SIZE(sring_native, XEN_PAGE_SIZE * nr_grefs);
218223 		break;
219224 	}
220225 	case BLKIF_PROTOCOL_X86_32:
221226 	{
222
-		struct blkif_x86_32_sring *sring_x86_32;
223
-		sring_x86_32 = (struct blkif_x86_32_sring *)ring->blk_ring;
224
-		BACK_RING_INIT(&ring->blk_rings.x86_32, sring_x86_32,
225
-			       XEN_PAGE_SIZE * nr_grefs);
227
+		struct blkif_x86_32_sring *sring_x86_32 =
228
+			(struct blkif_x86_32_sring *)ring->blk_ring;
229
+
230
+		BACK_RING_ATTACH(&ring->blk_rings.x86_32, sring_x86_32,
231
+				 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
232
+		size = __RING_SIZE(sring_x86_32, XEN_PAGE_SIZE * nr_grefs);
226233 		break;
227234 	}
228235 	case BLKIF_PROTOCOL_X86_64:
229236 	{
230
-		struct blkif_x86_64_sring *sring_x86_64;
231
-		sring_x86_64 = (struct blkif_x86_64_sring *)ring->blk_ring;
232
-		BACK_RING_INIT(&ring->blk_rings.x86_64, sring_x86_64,
233
-			       XEN_PAGE_SIZE * nr_grefs);
237
+		struct blkif_x86_64_sring *sring_x86_64 =
238
+			(struct blkif_x86_64_sring *)ring->blk_ring;
239
+
240
+		BACK_RING_ATTACH(&ring->blk_rings.x86_64, sring_x86_64,
241
+				 rsp_prod, XEN_PAGE_SIZE * nr_grefs);
242
+		size = __RING_SIZE(sring_x86_64, XEN_PAGE_SIZE * nr_grefs);
234243 		break;
235244 	}
236245 	default:
237246 		BUG();
238247 	}
239248 
249
+	err = -EIO;
250
+	if (req_prod - rsp_prod > size)
251
+		goto fail;
252
+
240253 	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->domid,
241254 			evtchn, xen_blkif_be_int, 0, "blkif-backend", ring);
242
-	if (err < 0) {
243
-		xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
244
-		ring->blk_rings.common.sring = NULL;
245
-		return err;
246
-	}
255
+	if (err < 0)
256
+		goto fail;
247257 	ring->irq = err;
248258 
249259 	return 0;
260
+
261
+fail:
262
+	xenbus_unmap_ring_vfree(blkif->be->dev, ring->blk_ring);
263
+	ring->blk_rings.common.sring = NULL;
264
+	return err;
250265 }
251266 
252267 static int xen_blkif_disconnect(struct xen_blkif *blkif)
....@@ -307,8 +322,7 @@
307322 		BUG_ON(atomic_read(&ring->persistent_gnt_in_use) != 0);
308323 		BUG_ON(!list_empty(&ring->persistent_purge_list));
309324 		BUG_ON(!RB_EMPTY_ROOT(&ring->persistent_gnts));
310
-		BUG_ON(!list_empty(&ring->free_pages));
311
-		BUG_ON(ring->free_pages_num != 0);
325
+		BUG_ON(ring->free_pages.num_pages != 0);
312326 		BUG_ON(ring->persistent_gnt_c != 0);
313327 		WARN_ON(i != (XEN_BLKIF_REQS_PER_PAGE * blkif->nr_ring_pages));
314328 		ring->active = false;
....@@ -349,6 +363,12 @@
349363 		return -ENOMEM;
350364 
351365 	return 0;
366
+}
367
+
368
+void xen_blkif_interface_fini(void)
369
+{
370
+	kmem_cache_destroy(xen_blkif_cachep);
371
+	xen_blkif_cachep = NULL;
352372 }
353373 
354374 /*
....@@ -450,7 +470,6 @@
450470 	device_remove_file(&dev->dev, &dev_attr_physical_device);
451471 }
452472 
453
-
454473 static void xen_vbd_free(struct xen_vbd *vbd)
455474 {
456475 	if (vbd->bdev)
....@@ -507,6 +526,7 @@
507526 		handle, blkif->domid);
508527 	return 0;
509528 }
529
+
510530 static int xen_blkbk_remove(struct xenbus_device *dev)
511531 {
512532 	struct backend_info *be = dev_get_drvdata(&dev->dev);
....@@ -590,6 +610,7 @@
590610 	if (err)
591611 		dev_warn(&dev->dev, "writing feature-discard (%d)", err);
592612 }
613
+
593614 int xen_blkbk_barrier(struct xenbus_transaction xbt,
594615 		      struct backend_info *be, int state)
595616 {
....@@ -674,7 +695,6 @@
674695 	xen_blkbk_remove(dev);
675696 	return err;
676697 }
677
-
678698 
679699 /*
680700  * Callback received when the hotplug scripts have placed the physical-device
....@@ -767,7 +787,6 @@
767787 	}
768788 }
769789 
770
-
771790 /*
772791  * Callback received when the frontend's state changes.
773792  */
....@@ -828,7 +847,7 @@
828847 		xenbus_switch_state(dev, XenbusStateClosed);
829848 		if (xenbus_dev_is_online(dev))
830849 			break;
831
-		/* fall through */
850
+		fallthrough;
832851 		/* if not online */
833852 	case XenbusStateUnknown:
834853 		/* implies xen_blkif_disconnect() via xen_blkbk_remove() */
....@@ -842,9 +861,27 @@
842861 	}
843862 }
844863 
864
+/* Once a memory pressure is detected, squeeze free page pools for a while. */
865
+static unsigned int buffer_squeeze_duration_ms = 10;
866
+module_param_named(buffer_squeeze_duration_ms,
867
+		buffer_squeeze_duration_ms, int, 0644);
868
+MODULE_PARM_DESC(buffer_squeeze_duration_ms,
869
+"Duration in ms to squeeze pages buffer when a memory pressure is detected");
870
+
871
+/*
872
+ * Callback received when the memory pressure is detected.
873
+ */
874
+static void reclaim_memory(struct xenbus_device *dev)
875
+{
876
+	struct backend_info *be = dev_get_drvdata(&dev->dev);
877
+
878
+	if (!be)
879
+		return;
880
+	be->blkif->buffer_squeeze_end = jiffies +
881
+		msecs_to_jiffies(buffer_squeeze_duration_ms);
882
+}
845883 
846884 /* ** Connection ** */
847
-
848885 
849886 /*
850887  * Write the physical details regarding the block device to the store, and
....@@ -873,7 +910,8 @@
873910 
874911 	xen_blkbk_barrier(xbt, be, be->blkif->vbd.flush_support);
875912 
876
-	err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u", 1);
913
+	err = xenbus_printf(xbt, dev->nodename, "feature-persistent", "%u",
914
+			be->blkif->vbd.feature_gnt_persistent_parm);
877915 	if (err) {
878916 		xenbus_dev_fatal(dev, err, "writing %s/feature-persistent",
879917 				 dev->nodename);
....@@ -937,7 +975,7 @@
937975 	int err, i, j;
938976 	struct xen_blkif *blkif = ring->blkif;
939977 	struct xenbus_device *dev = blkif->be->dev;
940
-	unsigned int ring_page_order, nr_grefs, evtchn;
978
+	unsigned int nr_grefs, evtchn;
941979 
942980 	err = xenbus_scanf(XBT_NIL, dir, "event-channel", "%u",
943981 			  &evtchn);
....@@ -947,43 +985,33 @@
947985 		return err;
948986 	}
949987 
950
-	err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
951
-			  &ring_page_order);
952
-	if (err != 1) {
953
-		err = xenbus_scanf(XBT_NIL, dir, "ring-ref", "%u", &ring_ref[0]);
988
+	nr_grefs = blkif->nr_ring_pages;
989
+
990
+	if (unlikely(!nr_grefs)) {
991
+		WARN_ON(true);
992
+		return -EINVAL;
993
+	}
994
+
995
+	for (i = 0; i < nr_grefs; i++) {
996
+		char ring_ref_name[RINGREF_NAME_LEN];
997
+
998
+		if (blkif->multi_ref)
999
+			snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
1000
+		else {
1001
+			WARN_ON(i != 0);
1002
+			snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref");
1003
+		}
1004
+
1005
+		err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
1006
+				   "%u", &ring_ref[i]);
1007
+
9541008 		if (err != 1) {
9551009 			err = -EINVAL;
956
-			xenbus_dev_fatal(dev, err, "reading %s/ring-ref", dir);
1010
+			xenbus_dev_fatal(dev, err, "reading %s/%s",
1011
+					 dir, ring_ref_name);
9571012 			return err;
958
-		}
959
-		nr_grefs = 1;
960
-	} else {
961
-		unsigned int i;
962
-
963
-		if (ring_page_order > xen_blkif_max_ring_order) {
964
-			err = -EINVAL;
965
-			xenbus_dev_fatal(dev, err, "%s/request %d ring page order exceed max:%d",
966
-					 dir, ring_page_order,
967
-					 xen_blkif_max_ring_order);
968
-			return err;
969
-		}
970
-
971
-		nr_grefs = 1 << ring_page_order;
972
-		for (i = 0; i < nr_grefs; i++) {
973
-			char ring_ref_name[RINGREF_NAME_LEN];
974
-
975
-			snprintf(ring_ref_name, RINGREF_NAME_LEN, "ring-ref%u", i);
976
-			err = xenbus_scanf(XBT_NIL, dir, ring_ref_name,
977
-					   "%u", &ring_ref[i]);
978
-			if (err != 1) {
979
-				err = -EINVAL;
980
-				xenbus_dev_fatal(dev, err, "reading %s/%s",
981
-						 dir, ring_ref_name);
982
-				return err;
983
-			}
9841013 		}
9851014 	}
986
-	blkif->nr_ring_pages = nr_grefs;
9871015 
9881016 	err = -ENOMEM;
9891017 	for (i = 0; i < nr_grefs * XEN_BLKIF_REQS_PER_PAGE; i++) {
....@@ -1034,35 +1062,39 @@
10341062 static int connect_ring(struct backend_info *be)
10351063 {
10361064 	struct xenbus_device *dev = be->dev;
1037
-	unsigned int pers_grants;
1065
+	struct xen_blkif *blkif = be->blkif;
10381066 	char protocol[64] = "";
10391067 	int err, i;
10401068 	char *xspath;
10411069 	size_t xspathsize;
10421070 	const size_t xenstore_path_ext_size = 11; /* sufficient for "/queue-NNN" */
10431071 	unsigned int requested_num_queues = 0;
1072
+	unsigned int ring_page_order;
10441073 
10451074 	pr_debug("%s %s\n", __func__, dev->otherend);
10461075 
1047
-	be->blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
1076
+	blkif->blk_protocol = BLKIF_PROTOCOL_DEFAULT;
10481077 	err = xenbus_scanf(XBT_NIL, dev->otherend, "protocol",
10491078 			   "%63s", protocol);
10501079 	if (err <= 0)
10511080 		strcpy(protocol, "unspecified, assuming default");
10521081 	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_NATIVE))
1053
-		be->blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
1082
+		blkif->blk_protocol = BLKIF_PROTOCOL_NATIVE;
10541083 	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_32))
1055
-		be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
1084
+		blkif->blk_protocol = BLKIF_PROTOCOL_X86_32;
10561085 	else if (0 == strcmp(protocol, XEN_IO_PROTO_ABI_X86_64))
1057
-		be->blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
1086
+		blkif->blk_protocol = BLKIF_PROTOCOL_X86_64;
10581087 	else {
10591088 		xenbus_dev_fatal(dev, err, "unknown fe protocol %s", protocol);
10601089 		return -ENOSYS;
10611090 	}
1062
-	pers_grants = xenbus_read_unsigned(dev->otherend, "feature-persistent",
1063
-					   0);
1064
-	be->blkif->vbd.feature_gnt_persistent = pers_grants;
1065
-	be->blkif->vbd.overflow_max_grants = 0;
1091
+
1092
+	blkif->vbd.feature_gnt_persistent_parm = feature_persistent;
1093
+	blkif->vbd.feature_gnt_persistent =
1094
+		blkif->vbd.feature_gnt_persistent_parm &&
1095
+		xenbus_read_unsigned(dev->otherend, "feature-persistent", 0);
1096
+
1097
+	blkif->vbd.overflow_max_grants = 0;
10661098 
10671099 	/*
10681100 	 * Read the number of hardware queues from frontend.
....@@ -1078,16 +1110,33 @@
10781110 				requested_num_queues, xenblk_max_queues);
10791111 		return -ENOSYS;
10801112 	}
1081
-	be->blkif->nr_rings = requested_num_queues;
1082
-	if (xen_blkif_alloc_rings(be->blkif))
1113
+	blkif->nr_rings = requested_num_queues;
1114
+	if (xen_blkif_alloc_rings(blkif))
10831115 		return -ENOMEM;
10841116 
10851117 	pr_info("%s: using %d queues, protocol %d (%s) %s\n", dev->nodename,
1086
-		 be->blkif->nr_rings, be->blkif->blk_protocol, protocol,
1087
-		 pers_grants ? "persistent grants" : "");
1118
+		 blkif->nr_rings, blkif->blk_protocol, protocol,
1119
+		 blkif->vbd.feature_gnt_persistent ? "persistent grants" : "");
10881120 
1089
-	if (be->blkif->nr_rings == 1)
1090
-		return read_per_ring_refs(&be->blkif->rings[0], dev->otherend);
1121
+	err = xenbus_scanf(XBT_NIL, dev->otherend, "ring-page-order", "%u",
1122
+			   &ring_page_order);
1123
+	if (err != 1) {
1124
+		blkif->nr_ring_pages = 1;
1125
+		blkif->multi_ref = false;
1126
+	} else if (ring_page_order <= xen_blkif_max_ring_order) {
1127
+		blkif->nr_ring_pages = 1 << ring_page_order;
1128
+		blkif->multi_ref = true;
1129
+	} else {
1130
+		err = -EINVAL;
1131
+		xenbus_dev_fatal(dev, err,
1132
+				 "requested ring page order %d exceed max:%d",
1133
+				 ring_page_order,
1134
+				 xen_blkif_max_ring_order);
1135
+		return err;
1136
+	}
1137
+
1138
+	if (blkif->nr_rings == 1)
1139
+		return read_per_ring_refs(&blkif->rings[0], dev->otherend);
10911140 	else {
10921141 		xspathsize = strlen(dev->otherend) + xenstore_path_ext_size;
10931142 		xspath = kmalloc(xspathsize, GFP_KERNEL);
....@@ -1096,10 +1145,10 @@
10961145 			return -ENOMEM;
10971146 		}
10981147 
1099
-		for (i = 0; i < be->blkif->nr_rings; i++) {
1148
+		for (i = 0; i < blkif->nr_rings; i++) {
11001149 			memset(xspath, 0, xspathsize);
11011150 			snprintf(xspath, xspathsize, "%s/queue-%u", dev->otherend, i);
1102
-			err = read_per_ring_refs(&be->blkif->rings[i], xspath);
1151
+			err = read_per_ring_refs(&blkif->rings[i], xspath);
11031152 			if (err) {
11041153 				kfree(xspath);
11051154 				return err;
....@@ -1119,10 +1168,17 @@
11191168 	.ids  = xen_blkbk_ids,
11201169 	.probe = xen_blkbk_probe,
11211170 	.remove = xen_blkbk_remove,
1122
-	.otherend_changed = frontend_changed
1171
+	.otherend_changed = frontend_changed,
1172
+	.allow_rebind = true,
1173
+	.reclaim_memory = reclaim_memory,
11231174 };
11241175 
11251176 int xen_blkif_xenbus_init(void)
11261177 {
11271178 	return xenbus_register_backend(&xen_blkbk_driver);
11281179 }
1180
+
1181
+void xen_blkif_xenbus_fini(void)
1182
+{
1183
+	xenbus_unregister_driver(&xen_blkbk_driver);
1184
+}