From 423d9322c20b379d7fe64b2ca9f1d035f15c08cd Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 4 Aug 2023 17:50:44 +0000
Subject: [PATCH 1/7] implement MTU change for netvsc driver

---
 drivers/bus/vmbus/vmbus_common.c |   4 +-
 drivers/net/netvsc/hn_ethdev.c   | 168 +++++++++++++++++++++++++------
 drivers/net/netvsc/hn_rndis.c    |   7 ++
 drivers/net/netvsc/hn_rndis.h    |   1 +
 drivers/net/netvsc/hn_var.h      |   2 +-
 5 files changed, 148 insertions(+), 34 deletions(-)

diff --git a/drivers/bus/vmbus/vmbus_common.c b/drivers/bus/vmbus/vmbus_common.c
index 95f3ad78bc8..fd205e8ac34 100644
--- a/drivers/bus/vmbus/vmbus_common.c
+++ b/drivers/bus/vmbus/vmbus_common.c
@@ -39,7 +39,9 @@ vmbus_map_resource(void *requested_addr, int fd, off_t offset, size_t size,
 			  "mmap(%d, %p, %zu, %ld) failed: %s",
 			  fd, requested_addr, size, (long)offset,
 			  strerror(errno));
-	}
+	} else
+		VMBUS_LOG(DEBUG, "  VMBUS memory mapped at %p",
+			  mapaddr);
 	return mapaddr;
 }
 
diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index d0bbc0a4c0c..f785c718fb8 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -1059,37 +1059,6 @@ hn_dev_close(struct rte_eth_dev *dev)
 	return ret;
 }
 
-static const struct eth_dev_ops hn_eth_dev_ops = {
-	.dev_configure		= hn_dev_configure,
-	.dev_start		= hn_dev_start,
-	.dev_stop		= hn_dev_stop,
-	.dev_close		= hn_dev_close,
-	.dev_infos_get		= hn_dev_info_get,
-	.txq_info_get		= hn_dev_tx_queue_info,
-	.rxq_info_get		= hn_dev_rx_queue_info,
-	.dev_supported_ptypes_get = hn_vf_supported_ptypes,
-	.promiscuous_enable     = hn_dev_promiscuous_enable,
-	.promiscuous_disable    = hn_dev_promiscuous_disable,
-	.allmulticast_enable    = hn_dev_allmulticast_enable,
-	.allmulticast_disable   = hn_dev_allmulticast_disable,
-	.set_mc_addr_list	= hn_dev_mc_addr_list,
-	.reta_update		= hn_rss_reta_update,
-	.reta_query             = hn_rss_reta_query,
-	.rss_hash_update	= hn_rss_hash_update,
-	.rss_hash_conf_get      = hn_rss_hash_conf_get,
-	.tx_queue_setup		= hn_dev_tx_queue_setup,
-	.tx_queue_release	= hn_dev_tx_queue_release,
-	.tx_done_cleanup        = hn_dev_tx_done_cleanup,
-	.rx_queue_setup		= hn_dev_rx_queue_setup,
-	.rx_queue_release	= hn_dev_rx_queue_release,
-	.link_update		= hn_dev_link_update,
-	.stats_get		= hn_dev_stats_get,
-	.stats_reset            = hn_dev_stats_reset,
-	.xstats_get		= hn_dev_xstats_get,
-	.xstats_get_names	= hn_dev_xstats_get_names,
-	.xstats_reset		= hn_dev_xstats_reset,
-};
-
 /*
  * Setup connection between PMD and kernel.
  */
@@ -1129,12 +1098,141 @@ hn_detach(struct hn_data *hv)
 	hn_rndis_detach(hv);
 }
 
+static int
+hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
+{
+	struct hn_data *hv = dev->data->dev_private;
+	struct rte_eth_dev *vf_dev;
+	unsigned int orig_mtu = dev->data->mtu;
+	uint32_t rndis_mtu;
+	int ret = 0;
+
+	if (dev->data->dev_started) {
+		PMD_DRV_LOG(ERR, "Device must be stopped before changing MTU");
+		return -EIO;
+	}
+
+	ret = hn_dev_close(dev);
+	if (ret)
+		return ret;
+
+	/* Change MTU of underlying VF netdev first, if it exists */
+	rte_rwlock_read_lock(&hv->vf_lock);
+	vf_dev = hn_get_vf_dev(hv);
+	if (hv->vf_ctx.vf_vsc_switched && vf_dev) {
+		ret = vf_dev->dev_ops->mtu_set(vf_dev, mtu);
+		if (ret) {
+			rte_rwlock_read_unlock(&hv->vf_lock);
+			goto out;
+		}
+	}
+	rte_rwlock_read_unlock(&hv->vf_lock);
+
+	/* Release channel resources */
+	hn_detach(hv);
+	hn_chim_uninit(dev);
+	rte_vmbus_chan_close(hv->channels[0]);
+
+	/* Unmap and re-map vmbus device */
+	rte_vmbus_unmap_device(hv->vmbus);
+	ret = rte_vmbus_map_device(hv->vmbus);
+	if (ret) {
+		/* This is a catastrophic error - the device is unusable */
+		PMD_DRV_LOG(ERR, "Could not re-map vmbus device!");
+		return ret;
+	}
+
+	/* Update pointers to re-mapped memory */
+	hv->rxbuf_res = hv->vmbus->resource[HV_RECV_BUF_MAP];
+	hv->chim_res  = hv->vmbus->resource[HV_SEND_BUF_MAP];
+
+	/* Re-open the vmbus channel */
+	ret = rte_vmbus_chan_open(hv->vmbus, &hv->channels[0]);
+	if (ret) {
+		/* This is a catastrophic error - the device is unusable */
+		PMD_DRV_LOG(ERR, "Could not re-open vmbus channel!");
+	}
+
+	rte_vmbus_set_latency(hv->vmbus, hv->channels[0], hv->latency);
+
+	hv->primary = hn_rx_queue_alloc(hv, 0,
+					dev->device->numa_node);
+
+	if (!hv->primary) {
+		/* This is a catastrophic error - the device is unusable */
+		PMD_DRV_LOG(ERR, "No memory to allocate rx queue!");
+		return -ENOMEM;
+	}
+
+	ret = hn_attach(hv, mtu);
+	if (ret)
+		goto error;
+
+	ret = hn_chim_init(dev);
+	if (!ret)
+		goto out;
+
+error:
+	/* In case of error, attempt rollback to original MTU */
+	if (hn_attach(hv, orig_mtu))
+		PMD_DRV_LOG(ERR, "Restoring original MTU failed");
+
+	rte_rwlock_read_lock(&hv->vf_lock);
+	vf_dev = hn_get_vf_dev(hv);
+	if (hv->vf_ctx.vf_vsc_switched && vf_dev)
+		vf_dev->dev_ops->mtu_set(vf_dev, orig_mtu);
+	rte_rwlock_read_unlock(&hv->vf_lock);
+
+out:
+	if (hn_rndis_get_mtu(hv, &rndis_mtu))
+		PMD_DRV_LOG(ERR, "Could not get MTU via RNDIS");
+	else {
+		dev->data->mtu = (uint16_t)rndis_mtu;
+		PMD_DRV_LOG(DEBUG, "RNDIS MTU is %u", dev->data->mtu);
+	}
+
+	return ret;
+}
+
+static const struct eth_dev_ops hn_eth_dev_ops = {
+	.dev_configure		= hn_dev_configure,
+	.dev_start		= hn_dev_start,
+	.dev_stop		= hn_dev_stop,
+	.dev_close		= hn_dev_close,
+	.dev_infos_get		= hn_dev_info_get,
+	.txq_info_get		= hn_dev_tx_queue_info,
+	.rxq_info_get		= hn_dev_rx_queue_info,
+	.dev_supported_ptypes_get = hn_vf_supported_ptypes,
+	.promiscuous_enable     = hn_dev_promiscuous_enable,
+	.promiscuous_disable    = hn_dev_promiscuous_disable,
+	.allmulticast_enable    = hn_dev_allmulticast_enable,
+	.allmulticast_disable   = hn_dev_allmulticast_disable,
+	.set_mc_addr_list	= hn_dev_mc_addr_list,
+	.mtu_set			= hn_dev_mtu_set,
+	.reta_update		= hn_rss_reta_update,
+	.reta_query             = hn_rss_reta_query,
+	.rss_hash_update	= hn_rss_hash_update,
+	.rss_hash_conf_get      = hn_rss_hash_conf_get,
+	.tx_queue_setup		= hn_dev_tx_queue_setup,
+	.tx_queue_release	= hn_dev_tx_queue_release,
+	.tx_done_cleanup        = hn_dev_tx_done_cleanup,
+	.rx_queue_setup		= hn_dev_rx_queue_setup,
+	.rx_queue_release	= hn_dev_rx_queue_release,
+	.link_update		= hn_dev_link_update,
+	.stats_get		= hn_dev_stats_get,
+	.stats_reset            = hn_dev_stats_reset,
+	.xstats_get		= hn_dev_xstats_get,
+	.xstats_get_names	= hn_dev_xstats_get_names,
+	.xstats_reset		= hn_dev_xstats_reset,
+};
+
 static int
 eth_hn_dev_init(struct rte_eth_dev *eth_dev)
 {
 	struct hn_data *hv = eth_dev->data->dev_private;
 	struct rte_device *device = eth_dev->device;
 	struct rte_vmbus_device *vmbus;
+	uint32_t mtu;
 	unsigned int rxr_cnt;
 	int err, max_chan;
 
@@ -1218,6 +1316,12 @@ eth_hn_dev_init(struct rte_eth_dev *eth_dev)
 	if (err)
 		goto failed;
 
+	err = hn_rndis_get_mtu(hv, &mtu);
+	if (err)
+		goto failed;
+	eth_dev->data->mtu = (uint16_t)mtu;
+	PMD_INIT_LOG(DEBUG, "RNDIS MTU is %u", eth_dev->data->mtu);
+
 	err = hn_rndis_get_eaddr(hv, eth_dev->data->mac_addrs->addr_bytes);
 	if (err)
 		goto failed;
@@ -1272,7 +1376,7 @@ eth_hn_dev_uninit(struct rte_eth_dev *eth_dev)
 
 	hn_detach(hv);
 	hn_chim_uninit(eth_dev);
-	rte_vmbus_chan_close(hv->primary->chan);
+	rte_vmbus_chan_close(hv->channels[0]);
 	rte_free(hv->primary);
 	ret = rte_eth_dev_owner_delete(hv->owner.id);
 	if (ret != 0)
diff --git a/drivers/net/netvsc/hn_rndis.c b/drivers/net/netvsc/hn_rndis.c
index 29c6009b2cb..778f86f2bfe 100644
--- a/drivers/net/netvsc/hn_rndis.c
+++ b/drivers/net/netvsc/hn_rndis.c
@@ -1111,6 +1111,13 @@ hn_rndis_get_eaddr(struct hn_data *hv, uint8_t *eaddr)
 	return 0;
 }
 
+int
+hn_rndis_get_mtu(struct hn_data *hv, uint32_t *mtu)
+{
+	return hn_rndis_query(hv, OID_GEN_MAXIMUM_FRAME_SIZE, NULL, 0,
+			       mtu, sizeof(uint32_t));
+}
+
 int
 hn_rndis_get_linkstatus(struct hn_data *hv)
 {
diff --git a/drivers/net/netvsc/hn_rndis.h b/drivers/net/netvsc/hn_rndis.h
index 9a8251fc2fb..7f40f6221de 100644
--- a/drivers/net/netvsc/hn_rndis.h
+++ b/drivers/net/netvsc/hn_rndis.h
@@ -10,6 +10,7 @@ void	hn_rndis_link_status(struct rte_eth_dev *dev, const void *msg);
 int	hn_rndis_attach(struct hn_data *hv);
 void	hn_rndis_detach(struct hn_data *hv);
 int	hn_rndis_get_eaddr(struct hn_data *hv, uint8_t *eaddr);
+int	hn_rndis_get_mtu(struct hn_data *hv, uint32_t *mtu);
 int	hn_rndis_get_linkstatus(struct hn_data *hv);
 int	hn_rndis_get_linkspeed(struct hn_data *hv);
 int	hn_rndis_set_rxfilter(struct hn_data *hv, uint32_t filter);
diff --git a/drivers/net/netvsc/hn_var.h b/drivers/net/netvsc/hn_var.h
index e1f8e69a286..ba7841ef5ef 100644
--- a/drivers/net/netvsc/hn_var.h
+++ b/drivers/net/netvsc/hn_var.h
@@ -13,7 +13,7 @@
  * Tunable ethdev params
  */
 #define HN_MIN_RX_BUF_SIZE	1024
-#define HN_MAX_XFER_LEN		2048
+#define HN_MAX_XFER_LEN		RTE_ETHER_MAX_JUMBO_FRAME_LEN
 #define	HN_MAX_MAC_ADDRS	1
 #define HN_MAX_CHANNELS		64
 

From 5f2675dbe32e2916a9832e1312c2e49986290455 Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 1 Sep 2023 00:18:54 +0000
Subject: [PATCH 2/7] do not close device, do not re-allocate queues, simply
 assign new vmbus channels to pre-existing queues

---
 drivers/net/netvsc/hn_ethdev.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index f785c718fb8..10762816419 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -1102,6 +1102,8 @@ static int
 hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 {
 	struct hn_data *hv = dev->data->dev_private;
+	struct hn_rx_queue *rxq = dev->data->rx_queues[0];
+	struct hn_tx_queue *txq = dev->data->tx_queues[0];
 	struct rte_eth_dev *vf_dev;
 	unsigned int orig_mtu = dev->data->mtu;
 	uint32_t rndis_mtu;
@@ -1112,10 +1114,6 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 		return -EIO;
 	}
 
-	ret = hn_dev_close(dev);
-	if (ret)
-		return ret;
-
 	/* Change MTU of underlying VF netdev first, if it exists */
 	rte_rwlock_read_lock(&hv->vf_lock);
 	vf_dev = hn_get_vf_dev(hv);
@@ -1131,6 +1129,8 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 	/* Release channel resources */
 	hn_detach(hv);
 	hn_chim_uninit(dev);
+
+	/* Close primary channel */
 	rte_vmbus_chan_close(hv->channels[0]);
 
 	/* Unmap and re-map vmbus device */
@@ -1155,20 +1155,18 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 
 	rte_vmbus_set_latency(hv->vmbus, hv->channels[0], hv->latency);
 
-	hv->primary = hn_rx_queue_alloc(hv, 0,
-					dev->device->numa_node);
-
-	if (!hv->primary) {
-		/* This is a catastrophic error - the device is unusable */
-		PMD_DRV_LOG(ERR, "No memory to allocate rx queue!");
-		return -ENOMEM;
-	}
+	rxq->chan = hv->channels[0];
+	txq->chan = hv->channels[0];
 
 	ret = hn_attach(hv, mtu);
 	if (ret)
 		goto error;
 
 	ret = hn_chim_init(dev);
+	if (ret)
+		goto error;
+
+	ret = hn_dev_configure(dev);
 	if (!ret)
 		goto out;
 

From b590c764319858ceb8bc7c9e12cd9b0d236f6ba0 Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 8 Sep 2023 19:16:14 +0000
Subject: [PATCH 3/7] handle multiple queues when tearing down/re-creating
 vmbus channels to change mtu

---
 drivers/net/netvsc/hn_ethdev.c | 44 +++++++++++++++++++---------------
 1 file changed, 25 insertions(+), 19 deletions(-)

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index 10762816419..da64d58c1c9 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -1102,12 +1102,13 @@ static int
 hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 {
 	struct hn_data *hv = dev->data->dev_private;
-	struct hn_rx_queue *rxq = dev->data->rx_queues[0];
-	struct hn_tx_queue *txq = dev->data->tx_queues[0];
+	struct hn_rx_queue **rxqs = (struct hn_rx_queue **)dev->data->rx_queues;
+	struct hn_tx_queue **txqs = (struct hn_tx_queue **)dev->data->tx_queues;
 	struct rte_eth_dev *vf_dev;
 	unsigned int orig_mtu = dev->data->mtu;
 	uint32_t rndis_mtu;
 	int ret = 0;
+	int i;
 
 	if (dev->data->dev_started) {
 		PMD_DRV_LOG(ERR, "Device must be stopped before changing MTU");
@@ -1128,7 +1129,6 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 
 	/* Release channel resources */
 	hn_detach(hv);
-	hn_chim_uninit(dev);
 
 	/* Close primary channel */
 	rte_vmbus_chan_close(hv->channels[0]);
@@ -1142,7 +1142,7 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 		return ret;
 	}
 
-	/* Update pointers to re-mapped memory */
+	/* Update pointers to re-mapped UIO resources */
 	hv->rxbuf_res = hv->vmbus->resource[HV_RECV_BUF_MAP];
 	hv->chim_res  = hv->vmbus->resource[HV_SEND_BUF_MAP];
 
@@ -1155,23 +1155,37 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 
 	rte_vmbus_set_latency(hv->vmbus, hv->channels[0], hv->latency);
 
-	rxq->chan = hv->channels[0];
-	txq->chan = hv->channels[0];
+	/* Point primary queues at new primary channel */
+	rxqs[0]->chan = hv->channels[0];
+	txqs[0]->chan = hv->channels[0];
 
 	ret = hn_attach(hv, mtu);
 	if (ret)
 		goto error;
 
-	ret = hn_chim_init(dev);
+	/* Create vmbus subchannels, additional RNDIS configuration */
+	ret = hn_dev_configure(dev);
 	if (ret)
 		goto error;
+	
+	/* Point any additional queues at new subchannels */
+	for (i = 1; i < dev->data->nb_rx_queues; i++)
+		rxqs[i]->chan = hv->channels[i];
+	for (i = 1; i < dev->data->nb_tx_queues; i++)
+		txqs[i]->chan = hv->channels[i];
 
-	ret = hn_dev_configure(dev);
-	if (!ret)
-		goto out;
+out:
+	if (hn_rndis_get_mtu(hv, &rndis_mtu))
+		PMD_DRV_LOG(ERR, "Could not get MTU via RNDIS");
+	else {
+		dev->data->mtu = (uint16_t)rndis_mtu;
+		PMD_DRV_LOG(DEBUG, "RNDIS MTU is %u", dev->data->mtu);
+	}
+
+	return ret;
 
 error:
-	/* In case of error, attempt rollback to original MTU */
+	/* In case of error, attempt to restore original MTU */
 	if (hn_attach(hv, orig_mtu))
 		PMD_DRV_LOG(ERR, "Restoring original MTU failed");
 
@@ -1181,14 +1195,6 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 		vf_dev->dev_ops->mtu_set(vf_dev, orig_mtu);
 	rte_rwlock_read_unlock(&hv->vf_lock);
 
-out:
-	if (hn_rndis_get_mtu(hv, &rndis_mtu))
-		PMD_DRV_LOG(ERR, "Could not get MTU via RNDIS");
-	else {
-		dev->data->mtu = (uint16_t)rndis_mtu;
-		PMD_DRV_LOG(DEBUG, "RNDIS MTU is %u", dev->data->mtu);
-	}
-
 	return ret;
 }
 

From 96c5772f01583611b250b31a68a814980187e8e3 Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 8 Sep 2023 19:54:21 +0000
Subject: [PATCH 4/7] close vmbus subchannels before unmapping vmbus device

---
 drivers/net/netvsc/hn_ethdev.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index da64d58c1c9..da0be70fca7 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -1130,8 +1130,9 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 	/* Release channel resources */
 	hn_detach(hv);
 
-	/* Close primary channel */
-	rte_vmbus_chan_close(hv->channels[0]);
+	/* Close vmbus channels */
+	for (i = 0; i < hv->num_queues; i++)
+		rte_vmbus_chan_close(hv->channels[i]);
 
 	/* Unmap and re-map vmbus device */
 	rte_vmbus_unmap_device(hv->vmbus);

From 16da2e8b04454f9c32abac0f0540165f3145ed08 Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 29 Sep 2023 20:17:21 +0000
Subject: [PATCH 5/7] Refactor re-initialization after un/re-mapping vmbus
 channels into separate function. Move VF MTU change into separate function.
 Ensure that subchannels are reconnected if rolling back to original MTU.

---
 drivers/net/netvsc/hn_ethdev.c | 98 +++++++++++++++++++---------------
 drivers/net/netvsc/hn_var.h    |  1 +
 drivers/net/netvsc/hn_vf.c     | 15 ++++++
 3 files changed, 71 insertions(+), 43 deletions(-)

diff --git a/drivers/net/netvsc/hn_ethdev.c b/drivers/net/netvsc/hn_ethdev.c
index da0be70fca7..d5517dca789 100644
--- a/drivers/net/netvsc/hn_ethdev.c
+++ b/drivers/net/netvsc/hn_ethdev.c
@@ -1098,13 +1098,47 @@ hn_detach(struct hn_data *hv)
 	hn_rndis_detach(hv);
 }
 
+/*
+ * Connects EXISTING rx/tx queues to NEW vmbus channel(s), and
+ * re-initializes NDIS and RNDIS, including re-sending initial
+ * NDIS/RNDIS configuration. To be used after the underlying vmbus
+ * has been un- and re-mapped, e.g. as must happen when the device
+ * MTU is changed.
+ */
 static int
-hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
+hn_reinit(struct rte_eth_dev *dev, uint16_t mtu)
 {
 	struct hn_data *hv = dev->data->dev_private;
 	struct hn_rx_queue **rxqs = (struct hn_rx_queue **)dev->data->rx_queues;
 	struct hn_tx_queue **txqs = (struct hn_tx_queue **)dev->data->tx_queues;
-	struct rte_eth_dev *vf_dev;
+	int i, ret = 0;
+
+	/* Point primary queues at new primary channel */
+	rxqs[0]->chan = hv->channels[0];
+	txqs[0]->chan = hv->channels[0];
+
+	ret = hn_attach(hv, mtu);
+	if (ret)
+		return ret;
+
+	/* Create vmbus subchannels, additional RNDIS configuration */
+	ret = hn_dev_configure(dev);
+	if (ret)
+		return ret;
+
+	/* Point any additional queues at new subchannels */
+	for (i = 1; i < dev->data->nb_rx_queues; i++)
+		rxqs[i]->chan = hv->channels[i];
+	for (i = 1; i < dev->data->nb_tx_queues; i++)
+		txqs[i]->chan = hv->channels[i];
+
+	return ret;
+}
+
+static int
+hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
+{
+	struct hn_data *hv = dev->data->dev_private;
 	unsigned int orig_mtu = dev->data->mtu;
 	uint32_t rndis_mtu;
 	int ret = 0;
@@ -1115,25 +1149,21 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 		return -EIO;
 	}
 
-	/* Change MTU of underlying VF netdev first, if it exists */
-	rte_rwlock_read_lock(&hv->vf_lock);
-	vf_dev = hn_get_vf_dev(hv);
-	if (hv->vf_ctx.vf_vsc_switched && vf_dev) {
-		ret = vf_dev->dev_ops->mtu_set(vf_dev, mtu);
-		if (ret) {
-			rte_rwlock_read_unlock(&hv->vf_lock);
-			goto out;
-		}
-	}
-	rte_rwlock_read_unlock(&hv->vf_lock);
+	/* Change MTU of underlying VF dev first, if it exists */
+	ret = hn_vf_mtu_set(dev, mtu);
+	if (ret) 
+		return ret;
 
 	/* Release channel resources */
 	hn_detach(hv);
 
-	/* Close vmbus channels */
-	for (i = 0; i < hv->num_queues; i++)
+	/* Close any secondary vmbus channels */
+	for (i = 1; i < hv->num_queues; i++)
 		rte_vmbus_chan_close(hv->channels[i]);
 
+	/* Close primary vmbus channel */
+	rte_free(hv->channels[0]);
+
 	/* Unmap and re-map vmbus device */
 	rte_vmbus_unmap_device(hv->vmbus);
 	ret = rte_vmbus_map_device(hv->vmbus);
@@ -1147,33 +1177,28 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 	hv->rxbuf_res = hv->vmbus->resource[HV_RECV_BUF_MAP];
 	hv->chim_res  = hv->vmbus->resource[HV_SEND_BUF_MAP];
 
-	/* Re-open the vmbus channel */
+	/* Re-open the primary vmbus channel */
 	ret = rte_vmbus_chan_open(hv->vmbus, &hv->channels[0]);
 	if (ret) {
 		/* This is a catastrophic error - the device is unusable */
 		PMD_DRV_LOG(ERR, "Could not re-open vmbus channel!");
+		return ret;
 	}
 
 	rte_vmbus_set_latency(hv->vmbus, hv->channels[0], hv->latency);
 
-	/* Point primary queues at new primary channel */
-	rxqs[0]->chan = hv->channels[0];
-	txqs[0]->chan = hv->channels[0];
+	ret = hn_reinit(dev, mtu);
+	if (!ret)
+		goto out;
 
-	ret = hn_attach(hv, mtu);
+	/* In case of error, attempt to restore original MTU */
+	ret = hn_reinit(dev, orig_mtu);
 	if (ret)
-		goto error;
+		PMD_DRV_LOG(ERR, "Restoring original MTU failed for netvsc");
 
-	/* Create vmbus subchannels, additional RNDIS configuration */
-	ret = hn_dev_configure(dev);
+	ret = hn_vf_mtu_set(dev, orig_mtu);
 	if (ret)
-		goto error;
-	
-	/* Point any additional queues at new subchannels */
-	for (i = 1; i < dev->data->nb_rx_queues; i++)
-		rxqs[i]->chan = hv->channels[i];
-	for (i = 1; i < dev->data->nb_tx_queues; i++)
-		txqs[i]->chan = hv->channels[i];
+		PMD_DRV_LOG(ERR, "Restoring original MTU failed for VF");
 
 out:
 	if (hn_rndis_get_mtu(hv, &rndis_mtu))
@@ -1183,19 +1208,6 @@ hn_dev_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
 		PMD_DRV_LOG(DEBUG, "RNDIS MTU is %u", dev->data->mtu);
 	}
 
-	return ret;
-
-error:
-	/* In case of error, attempt to restore original MTU */
-	if (hn_attach(hv, orig_mtu))
-		PMD_DRV_LOG(ERR, "Restoring original MTU failed");
-
-	rte_rwlock_read_lock(&hv->vf_lock);
-	vf_dev = hn_get_vf_dev(hv);
-	if (hv->vf_ctx.vf_vsc_switched && vf_dev)
-		vf_dev->dev_ops->mtu_set(vf_dev, orig_mtu);
-	rte_rwlock_read_unlock(&hv->vf_lock);
-
 	return ret;
 }
 
diff --git a/drivers/net/netvsc/hn_var.h b/drivers/net/netvsc/hn_var.h
index ba7841ef5ef..e37946804db 100644
--- a/drivers/net/netvsc/hn_var.h
+++ b/drivers/net/netvsc/hn_var.h
@@ -287,6 +287,7 @@ int	hn_vf_rss_hash_update(struct rte_eth_dev *dev,
 int	hn_vf_reta_hash_update(struct rte_eth_dev *dev,
 			       struct rte_eth_rss_reta_entry64 *reta_conf,
 			       uint16_t reta_size);
+int hn_vf_mtu_set(struct rte_eth_dev *dev, uint16_t mtu);
 int	hn_eth_rmv_event_callback(uint16_t port_id,
 				  enum rte_eth_event_type event __rte_unused,
 				  void *cb_arg, void *out __rte_unused);
diff --git a/drivers/net/netvsc/hn_vf.c b/drivers/net/netvsc/hn_vf.c
index 782395d805e..2e96f0d92d2 100644
--- a/drivers/net/netvsc/hn_vf.c
+++ b/drivers/net/netvsc/hn_vf.c
@@ -778,3 +778,18 @@ int hn_vf_reta_hash_update(struct rte_eth_dev *dev,
 
 	return ret;
 }
+
+int hn_vf_mtu_set(struct rte_eth_dev *dev, uint16_t mtu)
+{
+	struct hn_data *hv = dev->data->dev_private;
+	struct rte_eth_dev *vf_dev;
+	int ret = 0;
+
+	rte_rwlock_read_lock(&hv->vf_lock);
+	vf_dev = hn_get_vf_dev(hv);
+	if (hv->vf_ctx.vf_vsc_switched && vf_dev)
+		ret = vf_dev->dev_ops->mtu_set(vf_dev, mtu);
+	rte_rwlock_read_unlock(&hv->vf_lock);
+
+	return ret;
+}

From 2f6584f877c1857dcb72df3d9dec6ef32c12dcbf Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 29 Sep 2023 21:37:47 +0000
Subject: [PATCH 6/7] Configure VF MTU on hot add

---
 drivers/net/netvsc/hn_vf.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/netvsc/hn_vf.c b/drivers/net/netvsc/hn_vf.c
index 2e96f0d92d2..404ddd0e775 100644
--- a/drivers/net/netvsc/hn_vf.c
+++ b/drivers/net/netvsc/hn_vf.c
@@ -239,7 +239,7 @@ int hn_vf_add(struct rte_eth_dev *dev, struct hn_data *hv)
 
 	port = hv->vf_ctx.vf_port;
 
-	/* If the primary device has started, this is a VF host add.
+	/* If the primary device has started, this is a VF hot add.
 	 * Configure and start VF device.
 	 */
 	if (dev->data->dev_started) {
@@ -264,6 +264,8 @@ int hn_vf_add(struct rte_eth_dev *dev, struct hn_data *hv)
 			goto exit;
 		}
 
+		ret = hn_vf_mtu_set(dev, dev->data->mtu);
+
 		PMD_DRV_LOG(NOTICE, "Starting VF port %d", port);
 		ret = rte_eth_dev_start(port);
 		if (ret) {

From b8cbd69102a37adb01c8d26f27433b809a22317f Mon Sep 17 00:00:00 2001
From: Sam Andrew <108894698+samuelandrew@users.noreply.github.com>
Date: Fri, 29 Sep 2023 21:44:03 +0000
Subject: [PATCH 7/7] Handle MTU set error on VF hot add

---
 drivers/net/netvsc/hn_vf.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/netvsc/hn_vf.c b/drivers/net/netvsc/hn_vf.c
index 404ddd0e775..90cb6f69236 100644
--- a/drivers/net/netvsc/hn_vf.c
+++ b/drivers/net/netvsc/hn_vf.c
@@ -265,6 +265,10 @@ int hn_vf_add(struct rte_eth_dev *dev, struct hn_data *hv)
 		}
 
 		ret = hn_vf_mtu_set(dev, dev->data->mtu);
+		if (ret) {
+			PMD_DRV_LOG(ERR, "Failed to set VF MTU");
+			goto exit;
+		}
 
 		PMD_DRV_LOG(NOTICE, "Starting VF port %d", port);
 		ret = rte_eth_dev_start(port);