bus/vmbus: fix ring buffer mapping in secondary process

The driver code had wrong assumption that all the addresses to ring buffers
in the secondary process are the same as those in the primary process. This
is not always correct as the channels could be mapped to different
addresses in the secondary process.

Fix this by keeping track of all the mapped addresses from the primary
process in the shared uio_res, and have second process map to the same
addresses.

Fixes: 831dba47bd ("bus/vmbus: add Hyper-V virtual bus support")
Cc: stable@dpdk.org

Reported-by: Jonathan Erb <jonathan.erb@banduracyber.com>
Signed-off-by: Long Li <longli@microsoft.com>
Acked-by: Stephen Hemminger <sthemmin@microsoft.com>

drivers/bus/vmbus/linux/vmbus_uio.c

@@ -11,6 +11,7 @@
 #include <sys/stat.h>
 #include <sys/mman.h>
 
+#include <rte_eal.h>
 #include <rte_log.h>
 #include <rte_bus.h>
 #include <rte_memory.h>
@@ -203,6 +204,37 @@ static int vmbus_uio_map_subchan(const struct rte_vmbus_device *dev,
 	struct stat sb;
 	void *mapaddr;
 	int fd;
+	struct mapped_vmbus_resource *uio_res;
+	int channel_idx;
+
+	uio_res = vmbus_uio_find_resource(dev);
+	if (!uio_res) {
+		VMBUS_LOG(ERR, "can not find resources for mapping subchan");
+		return -ENOMEM;
+	}
+
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+		if (uio_res->nb_subchannels >= UIO_MAX_SUBCHANNEL) {
+			VMBUS_LOG(ERR,
+				"exceeding max subchannels UIO_MAX_SUBCHANNEL(%d)",
+				UIO_MAX_SUBCHANNEL);
+			VMBUS_LOG(ERR, "Change UIO_MAX_SUBCHANNEL and recompile");
+			return -ENOMEM;
+		}
+	} else {
+		for (channel_idx = 0; channel_idx < uio_res->nb_subchannels;
+		     channel_idx++)
+			if (uio_res->subchannel_maps[channel_idx].relid ==
+					chan->relid)
+				break;
+		if (channel_idx == uio_res->nb_subchannels) {
+			VMBUS_LOG(ERR,
+				"couldn't find sub channel %d from shared mapping in primary",
+				chan->relid);
+			return -ENOMEM;
+		}
+		vmbus_map_addr = uio_res->subchannel_maps[channel_idx].addr;
+	}
 
 	snprintf(ring_path, sizeof(ring_path),
 		 "%s/%s/channels/%u/ring",
@@ -239,58 +271,33 @@ static int vmbus_uio_map_subchan(const struct rte_vmbus_device *dev,
 	if (mapaddr == MAP_FAILED)
 		return -EIO;
 
+	if (rte_eal_process_type() == RTE_PROC_PRIMARY) {
+
+		/* Add this mapping to uio_res for use by secondary */
+		uio_res->subchannel_maps[uio_res->nb_subchannels].relid =
+			chan->relid;
+		uio_res->subchannel_maps[uio_res->nb_subchannels].addr =
+			mapaddr;
+		uio_res->subchannel_maps[uio_res->nb_subchannels].size =
+			file_size;
+		uio_res->nb_subchannels++;
+
+		vmbus_map_addr = RTE_PTR_ADD(mapaddr, file_size);
+	} else {
+		if (mapaddr != vmbus_map_addr) {
+			VMBUS_LOG(ERR, "failed to map channel %d to addr %p",
+					chan->relid, mapaddr);
+			vmbus_unmap_resource(mapaddr, file_size);
+			return -EIO;
+		}
+	}
+
 	*ring_size = file_size / 2;
 	*ring_buf = mapaddr;
 
-	vmbus_map_addr = RTE_PTR_ADD(mapaddr, file_size);
 	return 0;
 }
 
-int
-vmbus_uio_map_secondary_subchan(const struct rte_vmbus_device *dev,
-				const struct vmbus_channel *chan)
-{
-	const struct vmbus_br *br = &chan->txbr;
-	char ring_path[PATH_MAX];
-	void *mapaddr, *ring_buf;
-	uint32_t ring_size;
-	int fd;
-
-	snprintf(ring_path, sizeof(ring_path),
-		 "%s/%s/channels/%u/ring",
-		 SYSFS_VMBUS_DEVICES, dev->device.name,
-		 chan->relid);
-
-	ring_buf = br->vbr;
-	ring_size = br->dsize + sizeof(struct vmbus_bufring);
-	VMBUS_LOG(INFO, "secondary ring_buf %p size %u",
-		  ring_buf, ring_size);
-
-	fd = open(ring_path, O_RDWR);
-	if (fd < 0) {
-		VMBUS_LOG(ERR, "Cannot open %s: %s",
-			  ring_path, strerror(errno));
-		return -errno;
-	}
-
-	mapaddr = vmbus_map_resource(ring_buf, fd, 0, 2 * ring_size, 0);
-	close(fd);
-
-	if (mapaddr == ring_buf)
-		return 0;
-
-	if (mapaddr == MAP_FAILED)
-		VMBUS_LOG(ERR,
-			  "mmap subchan %u in secondary failed", chan->relid);
-	else {
-		VMBUS_LOG(ERR,
-			  "mmap subchan %u in secondary address mismatch",
-			  chan->relid);
-		vmbus_unmap_resource(mapaddr, 2 * ring_size);
-	}
-	return -1;
-}
-
 int vmbus_uio_map_rings(struct vmbus_channel *chan)
 {
 	const struct rte_vmbus_device *dev = chan->device;

drivers/bus/vmbus/private.h

@@ -33,6 +33,13 @@ struct vmbus_map {
 	uint64_t size;	/* length */
 };
 
+#define UIO_MAX_SUBCHANNEL 128
+struct subchannel_map {
+	uint16_t relid;
+	void *addr;
+	uint64_t size;
+};
+
 /*
  * For multi-process we need to reproduce all vmbus mappings in secondary
  * processes, so save them in a tailq.
@@ -41,10 +48,14 @@ struct mapped_vmbus_resource {
 	TAILQ_ENTRY(mapped_vmbus_resource) next;
 
 	rte_uuid_t id;
+
 	int nb_maps;
-	struct vmbus_channel *primary;
 	struct vmbus_map maps[VMBUS_MAX_RESOURCE];
+
 	char path[PATH_MAX];
+
+	int nb_subchannels;
+	struct subchannel_map subchannel_maps[UIO_MAX_SUBCHANNEL];
 };
 
 TAILQ_HEAD(mapped_vmbus_res_list, mapped_vmbus_resource);
@@ -105,8 +116,6 @@ bool vmbus_uio_subchannels_supported(const struct rte_vmbus_device *dev,
 int vmbus_uio_get_subchan(struct vmbus_channel *primary,
 			  struct vmbus_channel **subchan);
 int vmbus_uio_map_rings(struct vmbus_channel *chan);
-int vmbus_uio_map_secondary_subchan(const struct rte_vmbus_device *dev,
-				    const struct vmbus_channel *chan);
 
 void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen);
 

drivers/bus/vmbus/vmbus_channel.c

@@ -351,10 +351,8 @@ int rte_vmbus_chan_open(struct rte_vmbus_device *device,
 
 	err = vmbus_chan_create(device, device->relid, 0,
 				device->monitor_id, new_chan);
-	if (!err) {
+	if (!err)
 		device->primary = *new_chan;
-		uio_res->primary = *new_chan;
-	}
 
 	return err;
 }

drivers/bus/vmbus/vmbus_common_uio.c

@@ -69,8 +69,10 @@ vmbus_uio_map_secondary(struct rte_vmbus_device *dev)
 					     fd, offset,
 					     uio_res->maps[i].size, 0);
 
-		if (mapaddr == uio_res->maps[i].addr)
+		if (mapaddr == uio_res->maps[i].addr) {
+			dev->resource[i].addr = mapaddr;
 			continue;	/* successful map */
+		}
 
 		if (mapaddr == MAP_FAILED)
 			VMBUS_LOG(ERR,
@@ -88,19 +90,39 @@ vmbus_uio_map_secondary(struct rte_vmbus_device *dev)
 	/* fd is not needed in secondary process, close it */
 	close(fd);
 
-	dev->primary = uio_res->primary;
-	if (!dev->primary) {
-		VMBUS_LOG(ERR, "missing primary channel");
-		return -1;
+	/* Create and map primary channel */
+	if (vmbus_chan_create(dev, dev->relid, 0,
+					dev->monitor_id, &dev->primary)) {
+		VMBUS_LOG(ERR, "cannot create primary channel");
+		goto failed_primary;
 	}
 
-	STAILQ_FOREACH(chan, &dev->primary->subchannel_list, next) {
-		if (vmbus_uio_map_secondary_subchan(dev, chan) != 0) {
-			VMBUS_LOG(ERR, "cannot map secondary subchan");
-			return -1;
+	/* Create and map sub channels */
+	for (i = 0; i < uio_res->nb_subchannels; i++) {
+		if (rte_vmbus_subchan_open(dev->primary, &chan)) {
+			VMBUS_LOG(ERR,
+				"failed to create subchannel at index %d", i);
+			goto failed_secondary;
 		}
 	}
+
 	return 0;
+
+failed_secondary:
+	while (!STAILQ_EMPTY(&dev->primary->subchannel_list)) {
+		chan = STAILQ_FIRST(&dev->primary->subchannel_list);
+		vmbus_unmap_resource(chan->txbr.vbr, chan->txbr.dsize * 2);
+		rte_vmbus_chan_close(chan);
+	}
+	rte_vmbus_chan_close(dev->primary);
+
+failed_primary:
+	for (i = 0; i != uio_res->nb_maps; i++) {
+		vmbus_unmap_resource(
+				uio_res->maps[i].addr, uio_res->maps[i].size);
+	}
+
+	return -1;
 }
 
 static int
@@ -188,6 +210,11 @@ vmbus_uio_unmap(struct mapped_vmbus_resource *uio_res)
 	if (uio_res == NULL)
 		return;
 
+	for (i = 0; i < uio_res->nb_subchannels; i++) {
+		vmbus_unmap_resource(uio_res->subchannel_maps[i].addr,
+				uio_res->subchannel_maps[i].size);
+	}
+
 	for (i = 0; i != uio_res->nb_maps; i++) {
 		vmbus_unmap_resource(uio_res->maps[i].addr,
 				     (size_t)uio_res->maps[i].size);
@@ -211,8 +238,11 @@ vmbus_uio_unmap_resource(struct rte_vmbus_device *dev)
 		return;
 
 	/* secondary processes - just free maps */
-	if (rte_eal_process_type() != RTE_PROC_PRIMARY)
-		return vmbus_uio_unmap(uio_res);
+	if (rte_eal_process_type() != RTE_PROC_PRIMARY) {
+		vmbus_uio_unmap(uio_res);
+		rte_free(dev->primary);
+		return;
+	}
 
 	TAILQ_REMOVE(uio_res_list, uio_res, next);