Message-Id: <20210802120720.547894-2-fuguancheng@bytedance.com>
Date:   Mon,  2 Aug 2021 20:07:17 +0800
From:   fuguancheng <fuguancheng@...edance.com>
To:     mst@...hat.com, jasowang@...hat.com, stefanha@...hat.com,
        sgarzare@...hat.com, davem@...emloft.net, kuba@...nel.org,
        arseny.krasnov@...persky.com, andraprs@...zon.com,
        colin.king@...onical.com
Cc:     kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        fuguancheng <fuguancheng@...edance.com>
Subject: [PATCH 1/4] VSOCK DRIVER: Add multi-cid support for guest

This patch allowes the user to specify multiple additional CIDS
for the guest that can be used for communication between host
and guest.

The guest reads the additional cids from the device config space.
The device config space layout can be found at uapi/linux/virtio_vsock.h
The existing ioctl call for device VHOST_VIRTIO with request code
VHOST_VSOCK_SET_GUEST_CID is modified to notify the host for the
additional guest CIDS.

Signed-off-by: fuguancheng <fuguancheng@...edance.com>
---
 drivers/vhost/vhost.h             |   5 ++
 drivers/vhost/vsock.c             | 173 +++++++++++++++++++++++++++++---------
 include/net/af_vsock.h            |   1 +
 include/uapi/linux/vhost.h        |   7 ++
 include/uapi/linux/virtio_vsock.h |   3 +-
 net/vmw_vsock/af_vsock.c          |   6 +-
 net/vmw_vsock/virtio_transport.c  |  72 ++++++++++++++--
 net/vmw_vsock/vsock_loopback.c    |   8 ++
 8 files changed, 222 insertions(+), 53 deletions(-)

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 638bb640d6b4..52bd143ccf0c 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,6 +25,11 @@ struct vhost_work {
 	unsigned long		flags;
 };
 
+struct multi_cid_message {
+	u32 number_cid;
+	u64 *cid;
+};
+
 /* Poll a file (eventfd or socket) */
 /* Note: there's nothing vhost specific about this structure. */
 struct vhost_poll {
diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index f249622ef11b..f66c87de91b8 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -43,12 +43,25 @@ enum {
 static DEFINE_MUTEX(vhost_vsock_mutex);
 static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
 
+struct vhost_vsock_ref {
+	struct vhost_vsock *vsock;
+	struct hlist_node ref_hash;
+	u32 cid;
+};
+
+static bool vhost_transport_contain_cid(u32 cid)
+{
+	if (cid == VHOST_VSOCK_DEFAULT_HOST_CID)
+		return true;
+	return false;
+}
+
 struct vhost_vsock {
 	struct vhost_dev dev;
 	struct vhost_virtqueue vqs[2];
 
 	/* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
-	struct hlist_node hash;
+	struct vhost_vsock_ref *ref_list;
 
 	struct vhost_work send_pkt_work;
 	spinlock_t send_pkt_list_lock;
@@ -56,7 +69,8 @@ struct vhost_vsock {
 
 	atomic_t queued_replies;
 
-	u32 guest_cid;
+	u32 *cids;
+	u32 num_cid;
 	bool seqpacket_allow;
 };
 
@@ -70,23 +84,49 @@ static u32 vhost_transport_get_local_cid(void)
  */
 static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
 {
-	struct vhost_vsock *vsock;
+	struct vhost_vsock_ref *ref;
 
-	hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
-		u32 other_cid = vsock->guest_cid;
+	hash_for_each_possible_rcu(vhost_vsock_hash, ref, ref_hash, guest_cid) {
+		u32 other_cid = ref->cid;
 
 		/* Skip instances that have no CID yet */
 		if (other_cid == 0)
 			continue;
 
 		if (other_cid == guest_cid)
-			return vsock;
+			return ref->vsock;
 
 	}
 
 	return NULL;
 }
 
+static int check_if_cid_valid(u64 guest_cid, struct vhost_vsock *vsock)
+{
+	struct vhost_vsock *other;
+
+	if (guest_cid <= VMADDR_CID_HOST || guest_cid == U32_MAX)
+		return -EINVAL;
+
+	/* 64-bit CIDs are not yet supported */
+	if (guest_cid > U32_MAX)
+		return -EINVAL;
+	/* Refuse if CID is assigned to the guest->host transport (i.e. nested
+	 * VM), to make the loopback work.
+	 */
+	if (vsock_find_cid(guest_cid))
+		return -EADDRINUSE;
+	/* Refuse if CID is already in use */
+	mutex_lock(&vhost_vsock_mutex);
+	other = vhost_vsock_get(guest_cid);
+	if (other) {
+		mutex_unlock(&vhost_vsock_mutex);
+		return -EADDRINUSE;
+	}
+	mutex_unlock(&vhost_vsock_mutex);
+	return 0;
+}
+
 static void
 vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
 			    struct vhost_virtqueue *vq)
@@ -427,6 +467,7 @@ static struct virtio_transport vhost_transport = {
 		.module                   = THIS_MODULE,
 
 		.get_local_cid            = vhost_transport_get_local_cid,
+		.contain_cid              = vhost_transport_contain_cid,
 
 		.init                     = virtio_transport_do_socket_init,
 		.destruct                 = virtio_transport_destruct,
@@ -542,9 +583,9 @@ static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
 		virtio_transport_deliver_tap_pkt(pkt);
 
 		/* Only accept correctly addressed packets */
-		if (le64_to_cpu(pkt->hdr.src_cid) == vsock->guest_cid &&
-		    le64_to_cpu(pkt->hdr.dst_cid) ==
-		    vhost_transport_get_local_cid())
+		if (vsock->num_cid > 0 &&
+		    (pkt->hdr.src_cid) == vsock->cids[0] &&
+		    le64_to_cpu(pkt->hdr.dst_cid) == vhost_transport_get_local_cid())
 			virtio_transport_recv_pkt(&vhost_transport, pkt);
 		else
 			virtio_transport_free_pkt(pkt);
@@ -655,6 +696,10 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock)
 
 static void vhost_vsock_free(struct vhost_vsock *vsock)
 {
+	if (vsock->ref_list)
+		kvfree(vsock->ref_list);
+	if (vsock->cids)
+		kvfree(vsock->cids);
 	kvfree(vsock);
 }
 
@@ -677,7 +722,9 @@ static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
 		goto out;
 	}
 
-	vsock->guest_cid = 0; /* no CID assigned yet */
+	vsock->ref_list = NULL;
+	vsock->cids = NULL;
+	vsock->num_cid = 0;
 
 	atomic_set(&vsock->queued_replies, 0);
 
@@ -739,11 +786,14 @@ static void vhost_vsock_reset_orphans(struct sock *sk)
 
 static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
 {
+	int index;
 	struct vhost_vsock *vsock = file->private_data;
 
 	mutex_lock(&vhost_vsock_mutex);
-	if (vsock->guest_cid)
-		hash_del_rcu(&vsock->hash);
+	if (vsock->num_cid) {
+		for (index = 0; index < vsock->num_cid; index++)
+			hash_del_rcu(&vsock->ref_list[index].ref_hash);
+	}
 	mutex_unlock(&vhost_vsock_mutex);
 
 	/* Wait for other CPUs to finish using vsock */
@@ -774,41 +824,80 @@ static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
 	return 0;
 }
 
-static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
+static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 __user *cids, u32 number_cid)
 {
-	struct vhost_vsock *other;
+	u64 cid;
+	int i, ret;
 
-	/* Refuse reserved CIDs */
-	if (guest_cid <= VMADDR_CID_HOST ||
-	    guest_cid == U32_MAX)
+	if (number_cid <= 0)
 		return -EINVAL;
-
-	/* 64-bit CIDs are not yet supported */
-	if (guest_cid > U32_MAX)
-		return -EINVAL;
-
-	/* Refuse if CID is assigned to the guest->host transport (i.e. nested
-	 * VM), to make the loopback work.
-	 */
-	if (vsock_find_cid(guest_cid))
-		return -EADDRINUSE;
-
-	/* Refuse if CID is already in use */
-	mutex_lock(&vhost_vsock_mutex);
-	other = vhost_vsock_get(guest_cid);
-	if (other && other != vsock) {
+	/* delete the old CIDs. */
+	if (vsock->num_cid) {
+		mutex_lock(&vhost_vsock_mutex);
+		for (i = 0; i < vsock->num_cid; i++)
+			hash_del_rcu(&vsock->ref_list[i].ref_hash);
 		mutex_unlock(&vhost_vsock_mutex);
-		return -EADDRINUSE;
+		kvfree(vsock->ref_list);
+		vsock->ref_list = NULL;
+		kvfree(vsock->cids);
+		vsock->cids = NULL;
+	}
+	vsock->num_cid = number_cid;
+	vsock->cids = kmalloc_array(vsock->num_cid, sizeof(u32),
+				    GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!vsock->cids) {
+		vsock->num_cid = 0;
+		ret = -ENOMEM;
+		goto out;
+	}
+	vsock->ref_list = kvmalloc_array(vsock->num_cid, sizeof(*vsock->ref_list),
+			       GFP_KERNEL | __GFP_RETRY_MAYFAIL);
+	if (!vsock->ref_list) {
+		vsock->num_cid = 0;
+		ret = -ENOMEM;
+		goto out;
 	}
 
-	if (vsock->guest_cid)
-		hash_del_rcu(&vsock->hash);
-
-	vsock->guest_cid = guest_cid;
-	hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid);
-	mutex_unlock(&vhost_vsock_mutex);
+	for (i = 0; i < number_cid; i++) {
+		if (copy_from_user(&cid, cids + i, sizeof(cid))) {
+			/* record where we failed, to clean up the ref in hash table. */
+			vsock->num_cid = i;
+			ret = -EFAULT;
+			goto out;
+		}
+		ret = check_if_cid_valid(cid, vsock);
+		if (ret) {
+			vsock->num_cid = i;
+			goto out;
+		}
 
+		vsock->cids[i] = (u32)cid;
+		vsock->ref_list[i].cid = vsock->cids[i];
+		vsock->ref_list[i].vsock = vsock;
+		mutex_lock(&vhost_vsock_mutex);
+		hash_add_rcu(vhost_vsock_hash, &vsock->ref_list[i].ref_hash,
+			     vsock->cids[i]);
+		mutex_unlock(&vhost_vsock_mutex);
+	}
 	return 0;
+
+out:
+	/* Handle the memory release here. */
+	if (vsock->num_cid) {
+		mutex_lock(&vhost_vsock_mutex);
+		for (i = 0; i < vsock->num_cid; i++)
+			hash_del_rcu(&vsock->ref_list[i].ref_hash);
+		mutex_unlock(&vhost_vsock_mutex);
+		vsock->num_cid = 0;
+	}
+	if (vsock->ref_list)
+		kvfree(vsock->ref_list);
+	if (vsock->cids)
+		kvfree(vsock->cids);
+	/* Set it to null to prevent double release. */
+	vsock->ref_list = NULL;
+	vsock->cids = NULL;
+	return ret;
 }
 
 static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
@@ -852,16 +941,16 @@ static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
 {
 	struct vhost_vsock *vsock = f->private_data;
 	void __user *argp = (void __user *)arg;
-	u64 guest_cid;
 	u64 features;
 	int start;
 	int r;
+	struct multi_cid_message cid_message;
 
 	switch (ioctl) {
 	case VHOST_VSOCK_SET_GUEST_CID:
-		if (copy_from_user(&guest_cid, argp, sizeof(guest_cid)))
+		if (copy_from_user(&cid_message, argp, sizeof(cid_message)))
 			return -EFAULT;
-		return vhost_vsock_set_cid(vsock, guest_cid);
+		return vhost_vsock_set_cid(vsock, cid_message.cid, cid_message.number_cid);
 	case VHOST_VSOCK_SET_RUNNING:
 		if (copy_from_user(&start, argp, sizeof(start)))
 			return -EFAULT;
diff --git a/include/net/af_vsock.h b/include/net/af_vsock.h
index ab207677e0a8..d0fc08fb9cac 100644
--- a/include/net/af_vsock.h
+++ b/include/net/af_vsock.h
@@ -170,6 +170,7 @@ struct vsock_transport {
 
 	/* Addressing. */
 	u32 (*get_local_cid)(void);
+	bool (*contain_cid)(u32 cid);
 };
 
 /**** CORE ****/
diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
index c998860d7bbc..a3ea99f6fc7f 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -17,6 +17,13 @@
 
 #define VHOST_FILE_UNBIND -1
 
+/* structs used for hypervisors to send cid info. */
+
+struct multi_cid_message {
+	u32 number_cid;
+	u64 *cid;
+};
+
 /* ioctls */
 
 #define VHOST_VIRTIO 0xAF
diff --git a/include/uapi/linux/virtio_vsock.h b/include/uapi/linux/virtio_vsock.h
index 3dd3555b2740..0afc14446b01 100644
--- a/include/uapi/linux/virtio_vsock.h
+++ b/include/uapi/linux/virtio_vsock.h
@@ -42,7 +42,8 @@
 #define VIRTIO_VSOCK_F_SEQPACKET	1	/* SOCK_SEQPACKET supported */
 
 struct virtio_vsock_config {
-	__le64 guest_cid;
+	__le32 number_cid;
+	__le64 cids[];
 } __attribute__((packed));
 
 enum virtio_vsock_event_id {
diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 3e02cc3b24f8..4e1fbe74013f 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -507,13 +507,13 @@ EXPORT_SYMBOL_GPL(vsock_assign_transport);
 
 bool vsock_find_cid(unsigned int cid)
 {
-	if (transport_g2h && cid == transport_g2h->get_local_cid())
+	if (transport_g2h && transport_g2h->contain_cid(cid))
 		return true;
 
-	if (transport_h2g && cid == VMADDR_CID_HOST)
+	if (transport_h2g && transport_h2g->contain_cid(cid))
 		return true;
 
-	if (transport_local && cid == VMADDR_CID_LOCAL)
+	if (transport_local && transport_local->contain_cid(cid))
 		return true;
 
 	return false;
diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
index e0c2c992ad9c..5f256a57d9ae 100644
--- a/net/vmw_vsock/virtio_transport.c
+++ b/net/vmw_vsock/virtio_transport.c
@@ -61,10 +61,41 @@ struct virtio_vsock {
 	bool event_run;
 	struct virtio_vsock_event event_list[8];
 
-	u32 guest_cid;
+	/* The following fields are used to hold additional cids given by the hypervisor
+	 * such as qemu.
+	 */
+	u32 number_cid;
+	u32 *cids;
+
 	bool seqpacket_allow;
 };
 
+static bool virtio_transport_contain_cid(u32 cid)
+{
+	struct virtio_vsock *vsock;
+	bool ret;
+	u32 num_cid;
+
+	num_cid = 0;
+	rcu_read_lock();
+	vsock = rcu_dereference(the_virtio_vsock);
+	if (!vsock || !vsock->number_cid) {
+		ret = false;
+		goto out_rcu;
+	}
+
+	for (num_cid = 0; num_cid < vsock->number_cid; num_cid++) {
+		if (vsock->cids[num_cid] == cid) {
+			ret = true;
+			goto out_rcu;
+		}
+	}
+	ret = false;
+out_rcu:
+	rcu_read_unlock();
+	return ret;
+}
+
 static u32 virtio_transport_get_local_cid(void)
 {
 	struct virtio_vsock *vsock;
@@ -72,12 +103,12 @@ static u32 virtio_transport_get_local_cid(void)
 
 	rcu_read_lock();
 	vsock = rcu_dereference(the_virtio_vsock);
-	if (!vsock) {
+	if (!vsock || !vsock->number_cid) {
 		ret = VMADDR_CID_ANY;
 		goto out_rcu;
 	}
 
-	ret = vsock->guest_cid;
+	ret = vsock->cids[0];
 out_rcu:
 	rcu_read_unlock();
 	return ret;
@@ -176,7 +207,7 @@ virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
 		goto out_rcu;
 	}
 
-	if (le64_to_cpu(pkt->hdr.dst_cid) == vsock->guest_cid) {
+	if (le64_to_cpu(pkt->hdr.dst_cid) == vsock->cids[0]) {
 		virtio_transport_free_pkt(pkt);
 		len = -ENODEV;
 		goto out_rcu;
@@ -368,10 +399,33 @@ static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
 {
 	struct virtio_device *vdev = vsock->vdev;
 	__le64 guest_cid;
+	__le32 number_cid;
+	u32 index;
 
-	vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
-			  &guest_cid, sizeof(guest_cid));
-	vsock->guest_cid = le64_to_cpu(guest_cid);
+	vdev->config->get(vdev, offsetof(struct virtio_vsock_config, number_cid),
+			  &number_cid, sizeof(number_cid));
+	vsock->number_cid = le32_to_cpu(number_cid);
+
+	/* number_cid must be greater than 0 in the config space
+	 * to use this feature.
+	 */
+	if (vsock->number_cid > 0) {
+		vsock->cids = kmalloc_array(vsock->number_cid, sizeof(u32), GFP_KERNEL);
+		if (!vsock->cids) {
+			/* Space allocated failed, reset number_cid to 0.
+			 * only use the original guest_cid.
+			 */
+			vsock->number_cid = 0;
+		}
+	}
+
+	for (index = 0; index < vsock->number_cid; index++) {
+		vdev->config->get(vdev,
+				  offsetof(struct virtio_vsock_config, cids)
+				  + index * sizeof(uint64_t),
+				  &guest_cid, sizeof(guest_cid));
+		vsock->cids[index] = le64_to_cpu(guest_cid);
+	}
 }
 
 /* event_lock must be held */
@@ -451,6 +505,7 @@ static struct virtio_transport virtio_transport = {
 		.module                   = THIS_MODULE,
 
 		.get_local_cid            = virtio_transport_get_local_cid,
+		.contain_cid              = virtio_transport_contain_cid,
 
 		.init                     = virtio_transport_do_socket_init,
 		.destruct                 = virtio_transport_destruct,
@@ -594,6 +649,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	}
 
 	vsock->vdev = vdev;
+	vsock->cids = NULL;
+	vsock->number_cid = 0;
 
 	ret = virtio_find_vqs(vsock->vdev, VSOCK_VQ_MAX,
 			      vsock->vqs, callbacks, names,
@@ -713,6 +770,7 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
 
 	mutex_unlock(&the_virtio_vsock_mutex);
 
+	kfree(vsock->cids);
 	kfree(vsock);
 }
 
diff --git a/net/vmw_vsock/vsock_loopback.c b/net/vmw_vsock/vsock_loopback.c
index 169a8cf65b39..3abbbaff34eb 100644
--- a/net/vmw_vsock/vsock_loopback.c
+++ b/net/vmw_vsock/vsock_loopback.c
@@ -63,6 +63,13 @@ static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
 	return 0;
 }
 
+static bool vsock_loopback_contain_cid(u32 cid)
+{
+	if (cid == VMADDR_CID_LOCAL)
+		return true;
+	return false;
+}
+
 static bool vsock_loopback_seqpacket_allow(u32 remote_cid);
 
 static struct virtio_transport loopback_transport = {
@@ -70,6 +77,7 @@ static struct virtio_transport loopback_transport = {
 		.module                   = THIS_MODULE,
 
 		.get_local_cid            = vsock_loopback_get_local_cid,
+		.contain_cid              = vsock_loopback_contain_cid,
 
 		.init                     = virtio_transport_do_socket_init,
 		.destruct                 = virtio_transport_destruct,
-- 
2.11.0

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