Merge remote-tracking branch 'remotes/jasowang/tags/net-pull-request' into staging

# gpg: Signature made Mon 15 Mar 2021 08:42:25 GMT
# gpg:                using RSA key EF04965B398D6211
# gpg: Good signature from "Jason Wang (Jason Wang on RedHat) <jasowang@redhat.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 215D 46F4 8246 689E C77F  3562 EF04 965B 398D 6211

* remotes/jasowang/tags/net-pull-request:
  net: Do not fill legacy info_str for backends
  hmp: Use QAPI NetdevInfo in hmp_info_network
  net: Move NetClientState.info_str to dynamic allocations
  tests: Add tests for query-netdev command
  qapi: net: Add query-netdev command
  pvrdma: wean code off pvrdma_ring.h kernel header
  lan9118: switch to use qemu_receive_packet() for loopback
  cadence_gem: switch to use qemu_receive_packet() for loopback
  pcnet: switch to use qemu_receive_packet() for loopback
  rtl8139: switch to use qemu_receive_packet() for loopback
  tx_pkt: switch to use qemu_receive_packet_iov() for loopback
  sungem: switch to use qemu_receive_packet() for loopback
  msf2-mac: switch to use qemu_receive_packet() for loopback
  dp8393x: switch to use qemu_receive_packet() for loopback packet
  e1000: switch to use qemu_receive_packet() for loopback
  net: introduce qemu_receive_packet()
  e1000: fail early for evil descriptor
  net: validate that ids are well formed
  net: Fix build error when DEBUG_NET is on
  virtio-net: calculating proper msix vectors on init

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

# Conflicts:
#	hw/core/machine.c

38 files changed, 990 insertions, 224 deletions

diff --git a/hw/core/machine.c b/hw/core/machine.c
index 4c1a4a4c32..257a664ea2 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -40,6 +40,7 @@ GlobalProperty hw_compat_5_2[] = {
     { "ICH9-LPC", "smm-compat", "on"},
     { "PIIX4_PM", "smm-compat", "on"},
     { "virtio-blk-device", "report-discard-granularity", "off" },
+    { "virtio-net-pci", "vectors", "3"},
 };
 const size_t hw_compat_5_2_len = G_N_ELEMENTS(hw_compat_5_2);
 
diff --git a/hw/net/cadence_gem.c b/hw/net/cadence_gem.c
index 9a4474a084..24b3a0ff66 100644
--- a/hw/net/cadence_gem.c
+++ b/hw/net/cadence_gem.c
@@ -1275,8 +1275,8 @@ static void gem_transmit(CadenceGEMState *s)
                 /* Send the packet somewhere */
                 if (s->phy_loop || (s->regs[GEM_NWCTRL] &
                                     GEM_NWCTRL_LOCALLOOP)) {
-                    gem_receive(qemu_get_queue(s->nic), s->tx_packet,
-                                total_bytes);
+                    qemu_receive_packet(qemu_get_queue(s->nic), s->tx_packet,
+                                        total_bytes);
                 } else {
                     qemu_send_packet(qemu_get_queue(s->nic), s->tx_packet,
                                      total_bytes);
diff --git a/hw/net/dp8393x.c b/hw/net/dp8393x.c
index 205c0decc5..533a8304d0 100644
--- a/hw/net/dp8393x.c
+++ b/hw/net/dp8393x.c
@@ -506,7 +506,7 @@ static void dp8393x_do_transmit_packets(dp8393xState *s)
             s->regs[SONIC_TCR] |= SONIC_TCR_CRSL;
             if (nc->info->can_receive(nc)) {
                 s->loopback_packet = 1;
-                nc->info->receive(nc, s->tx_buffer, tx_len);
+                qemu_receive_packet(nc, s->tx_buffer, tx_len);
             }
         } else {
             /* Transmit packet */
diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index d8da2f6528..4f75b44cfc 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -546,7 +546,7 @@ e1000_send_packet(E1000State *s, const uint8_t *buf, int size)
 
     NetClientState *nc = qemu_get_queue(s->nic);
     if (s->phy_reg[PHY_CTRL] & MII_CR_LOOPBACK) {
-        nc->info->receive(nc, buf, size);
+        qemu_receive_packet(nc, buf, size);
     } else {
         qemu_send_packet(nc, buf, size);
     }
@@ -670,6 +670,9 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp)
         msh = tp->tso_props.hdr_len + tp->tso_props.mss;
         do {
             bytes = split_size;
+            if (tp->size >= msh) {
+                goto eop;
+            }
             if (tp->size + bytes > msh)
                 bytes = msh - tp->size;
 
@@ -695,6 +698,7 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp)
         tp->size += split_size;
     }
 
+eop:
     if (!(txd_lower & E1000_TXD_CMD_EOP))
         return;
     if (!(tp->cptse && tp->size < tp->tso_props.hdr_len)) {
diff --git a/hw/net/lan9118.c b/hw/net/lan9118.c
index abc796285a..6aff424cbe 100644
--- a/hw/net/lan9118.c
+++ b/hw/net/lan9118.c
@@ -680,7 +680,7 @@ static void do_tx_packet(lan9118_state *s)
     /* FIXME: Honor TX disable, and allow queueing of packets.  */
     if (s->phy_control & 0x4000)  {
         /* This assumes the receive routine doesn't touch the VLANClient.  */
-        lan9118_receive(qemu_get_queue(s->nic), s->txp->data, s->txp->len);
+        qemu_receive_packet(qemu_get_queue(s->nic), s->txp->data, s->txp->len);
     } else {
         qemu_send_packet(qemu_get_queue(s->nic), s->txp->data, s->txp->len);
     }
diff --git a/hw/net/msf2-emac.c b/hw/net/msf2-emac.c
index 32ba9e8412..3e6206044f 100644
--- a/hw/net/msf2-emac.c
+++ b/hw/net/msf2-emac.c
@@ -158,7 +158,7 @@ static void msf2_dma_tx(MSF2EmacState *s)
          * R_CFG1 bit 0 is set.
          */
         if (s->regs[R_CFG1] & R_CFG1_LB_EN_MASK) {
-            nc->info->receive(nc, buf, size);
+            qemu_receive_packet(nc, buf, size);
         } else {
             qemu_send_packet(nc, buf, size);
         }
diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
index da262edc3e..1f9aa59eca 100644
--- a/hw/net/net_tx_pkt.c
+++ b/hw/net/net_tx_pkt.c
@@ -553,7 +553,7 @@ static inline void net_tx_pkt_sendv(struct NetTxPkt *pkt,
     NetClientState *nc, const struct iovec *iov, int iov_cnt)
 {
     if (pkt->is_loopback) {
-        nc->info->receive_iov(nc, iov, iov_cnt);
+        qemu_receive_packet_iov(nc, iov, iov_cnt);
     } else {
         qemu_sendv_packet(nc, iov, iov_cnt);
     }
diff --git a/hw/net/pcnet.c b/hw/net/pcnet.c
index f3f18d8598..dcd3fc4948 100644
--- a/hw/net/pcnet.c
+++ b/hw/net/pcnet.c
@@ -1250,7 +1250,7 @@ txagain:
             if (BCR_SWSTYLE(s) == 1)
                 add_crc = !GET_FIELD(tmd.status, TMDS, NOFCS);
             s->looptest = add_crc ? PCNET_LOOPTEST_CRC : PCNET_LOOPTEST_NOCRC;
-            pcnet_receive(qemu_get_queue(s->nic), s->buffer, s->xmit_pos);
+            qemu_receive_packet(qemu_get_queue(s->nic), s->buffer, s->xmit_pos);
             s->looptest = 0;
         } else {
             if (s->nic) {
diff --git a/hw/net/rtl8139.c b/hw/net/rtl8139.c
index 4675ac878e..90b4fc63ce 100644
--- a/hw/net/rtl8139.c
+++ b/hw/net/rtl8139.c
@@ -1795,7 +1795,7 @@ static void rtl8139_transfer_frame(RTL8139State *s, uint8_t *buf, int size,
         }
 
         DPRINTF("+++ transmit loopback mode\n");
-        rtl8139_do_receive(qemu_get_queue(s->nic), buf, size, do_interrupt);
+        qemu_receive_packet(qemu_get_queue(s->nic), buf, size);
 
         if (iov) {
             g_free(buf2);
diff --git a/hw/net/sungem.c b/hw/net/sungem.c
index 33c3722df6..3684a4d733 100644
--- a/hw/net/sungem.c
+++ b/hw/net/sungem.c
@@ -306,7 +306,7 @@ static void sungem_send_packet(SunGEMState *s, const uint8_t *buf,
     NetClientState *nc = qemu_get_queue(s->nic);
 
     if (s->macregs[MAC_XIFCFG >> 2] & MAC_XIFCFG_LBCK) {
-        nc->info->receive(nc, buf, size);
+        qemu_receive_packet(nc, buf, size);
     } else {
         qemu_send_packet(nc, buf, size);
     }
diff --git a/hw/net/xen_nic.c b/hw/net/xen_nic.c
index 5c815b4f0c..8431808ea0 100644
--- a/hw/net/xen_nic.c
+++ b/hw/net/xen_nic.c
@@ -296,9 +296,8 @@ static int net_init(struct XenLegacyDevice *xendev)
     netdev->nic = qemu_new_nic(&net_xen_info, &netdev->conf,
                                "xen", NULL, netdev);
 
-    snprintf(qemu_get_queue(netdev->nic)->info_str,
-             sizeof(qemu_get_queue(netdev->nic)->info_str),
-             "nic: xenbus vif macaddr=%s", netdev->mac);
+    qemu_get_queue(netdev->nic)->info_str = g_strdup_printf(
+        "nic: xenbus vif macaddr=%s", netdev->mac);
 
     /* fill info */
     xenstore_write_be_int(&netdev->xendev, "feature-rx-copy", 1);
diff --git a/hw/rdma/vmw/pvrdma.h b/hw/rdma/vmw/pvrdma.h
index 1d36a76f1e..d08965d3e2 100644
--- a/hw/rdma/vmw/pvrdma.h
+++ b/hw/rdma/vmw/pvrdma.h
@@ -26,7 +26,6 @@
 #include "../rdma_backend_defs.h"
 #include "../rdma_rm_defs.h"
 
-#include "standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h"
 #include "standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_dev_api.h"
 #include "pvrdma_dev_ring.h"
 #include "qom/object.h"
@@ -64,10 +63,10 @@ typedef struct DSRInfo {
     union pvrdma_cmd_req *req;
     union pvrdma_cmd_resp *rsp;
 
-    struct pvrdma_ring *async_ring_state;
+    PvrdmaRingState *async_ring_state;
     PvrdmaRing async;
 
-    struct pvrdma_ring *cq_ring_state;
+    PvrdmaRingState *cq_ring_state;
     PvrdmaRing cq;
 } DSRInfo;
 
diff --git a/hw/rdma/vmw/pvrdma_cmd.c b/hw/rdma/vmw/pvrdma_cmd.c
index 692125ac26..f59879e257 100644
--- a/hw/rdma/vmw/pvrdma_cmd.c
+++ b/hw/rdma/vmw/pvrdma_cmd.c
@@ -262,7 +262,7 @@ static int create_cq_ring(PCIDevice *pci_dev , PvrdmaRing **ring,
     r = g_malloc(sizeof(*r));
     *ring = r;
 
-    r->ring_state = (struct pvrdma_ring *)
+    r->ring_state = (PvrdmaRingState *)
         rdma_pci_dma_map(pci_dev, tbl[0], TARGET_PAGE_SIZE);
 
     if (!r->ring_state) {
@@ -398,7 +398,7 @@ static int create_qp_rings(PCIDevice *pci_dev, uint64_t pdir_dma,
     *rings = sr;
 
     /* Create send ring */
-    sr->ring_state = (struct pvrdma_ring *)
+    sr->ring_state = (PvrdmaRingState *)
         rdma_pci_dma_map(pci_dev, tbl[0], TARGET_PAGE_SIZE);
     if (!sr->ring_state) {
         rdma_error_report("Failed to map to QP ring state");
@@ -639,7 +639,7 @@ static int create_srq_ring(PCIDevice *pci_dev, PvrdmaRing **ring,
     r = g_malloc(sizeof(*r));
     *ring = r;
 
-    r->ring_state = (struct pvrdma_ring *)
+    r->ring_state = (PvrdmaRingState *)
             rdma_pci_dma_map(pci_dev, tbl[0], TARGET_PAGE_SIZE);
     if (!r->ring_state) {
         rdma_error_report("Failed to map tp SRQ ring state");
diff --git a/hw/rdma/vmw/pvrdma_dev_ring.c b/hw/rdma/vmw/pvrdma_dev_ring.c
index f0bcde74b0..074ac59b84 100644
--- a/hw/rdma/vmw/pvrdma_dev_ring.c
+++ b/hw/rdma/vmw/pvrdma_dev_ring.c
@@ -22,11 +22,10 @@
 #include "trace.h"
 
 #include "../rdma_utils.h"
-#include "standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h"
 #include "pvrdma_dev_ring.h"
 
 int pvrdma_ring_init(PvrdmaRing *ring, const char *name, PCIDevice *dev,
-                     struct pvrdma_ring *ring_state, uint32_t max_elems,
+                     PvrdmaRingState *ring_state, uint32_t max_elems,
                      size_t elem_sz, dma_addr_t *tbl, uint32_t npages)
 {
     int i;
@@ -73,48 +72,54 @@ out:
 
 void *pvrdma_ring_next_elem_read(PvrdmaRing *ring)
 {
-    int e;
-    unsigned int idx = 0, offset;
+    unsigned int idx, offset;
+    const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail);
+    const uint32_t head = qatomic_read(&ring->ring_state->cons_head);
 
-    e = pvrdma_idx_ring_has_data(ring->ring_state, ring->max_elems, &idx);
-    if (e <= 0) {
+    if (tail & ~((ring->max_elems << 1) - 1) ||
+        head & ~((ring->max_elems << 1) - 1) ||
+        tail == head) {
         trace_pvrdma_ring_next_elem_read_no_data(ring->name);
         return NULL;
     }
 
+    idx = head & (ring->max_elems - 1);
     offset = idx * ring->elem_sz;
     return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE);
 }
 
 void pvrdma_ring_read_inc(PvrdmaRing *ring)
 {
-    pvrdma_idx_ring_inc(&ring->ring_state->cons_head, ring->max_elems);
+    uint32_t idx = qatomic_read(&ring->ring_state->cons_head);
+
+    idx = (idx + 1) & ((ring->max_elems << 1) - 1);
+    qatomic_set(&ring->ring_state->cons_head, idx);
 }
 
 void *pvrdma_ring_next_elem_write(PvrdmaRing *ring)
 {
-    int idx;
-    unsigned int offset, tail;
+    unsigned int idx, offset;
+    const uint32_t tail = qatomic_read(&ring->ring_state->prod_tail);
+    const uint32_t head = qatomic_read(&ring->ring_state->cons_head);
 
-    idx = pvrdma_idx_ring_has_space(ring->ring_state, ring->max_elems, &tail);
-    if (idx <= 0) {
+    if (tail & ~((ring->max_elems << 1) - 1) ||
+        head & ~((ring->max_elems << 1) - 1) ||
+        tail == (head ^ ring->max_elems)) {
         rdma_error_report("CQ is full");
         return NULL;
     }
 
-    idx = pvrdma_idx(&ring->ring_state->prod_tail, ring->max_elems);
-    if (idx < 0 || tail != idx) {
-        rdma_error_report("Invalid idx %d", idx);
-        return NULL;
-    }
-
+    idx = tail & (ring->max_elems - 1);
     offset = idx * ring->elem_sz;
     return ring->pages[offset / TARGET_PAGE_SIZE] + (offset % TARGET_PAGE_SIZE);
 }
 
 void pvrdma_ring_write_inc(PvrdmaRing *ring)
 {
-    pvrdma_idx_ring_inc(&ring->ring_state->prod_tail, ring->max_elems);
+    uint32_t idx = qatomic_read(&ring->ring_state->prod_tail);
+
+    idx = (idx + 1) & ((ring->max_elems << 1) - 1);
+    qatomic_set(&ring->ring_state->prod_tail, idx);
 }
 
 void pvrdma_ring_free(PvrdmaRing *ring)
diff --git a/hw/rdma/vmw/pvrdma_dev_ring.h b/hw/rdma/vmw/pvrdma_dev_ring.h
index 5f2a0cf9b9..d231588ce0 100644
--- a/hw/rdma/vmw/pvrdma_dev_ring.h
+++ b/hw/rdma/vmw/pvrdma_dev_ring.h
@@ -19,18 +19,23 @@
 
 #define MAX_RING_NAME_SZ 32
 
+typedef struct PvrdmaRingState {
+    int prod_tail; /* producer tail */
+    int cons_head; /* consumer head */
+} PvrdmaRingState;
+
 typedef struct PvrdmaRing {
     char name[MAX_RING_NAME_SZ];
     PCIDevice *dev;
     uint32_t max_elems;
     size_t elem_sz;
-    struct pvrdma_ring *ring_state; /* used only for unmap */
+    PvrdmaRingState *ring_state; /* used only for unmap */
     int npages;
     void **pages;
 } PvrdmaRing;
 
 int pvrdma_ring_init(PvrdmaRing *ring, const char *name, PCIDevice *dev,
-                     struct pvrdma_ring *ring_state, uint32_t max_elems,
+                     PvrdmaRingState *ring_state, uint32_t max_elems,
                      size_t elem_sz, dma_addr_t *tbl, uint32_t npages);
 void *pvrdma_ring_next_elem_read(PvrdmaRing *ring);
 void pvrdma_ring_read_inc(PvrdmaRing *ring);
diff --git a/hw/rdma/vmw/pvrdma_main.c b/hw/rdma/vmw/pvrdma_main.c
index 8593570332..84ae8024fc 100644
--- a/hw/rdma/vmw/pvrdma_main.c
+++ b/hw/rdma/vmw/pvrdma_main.c
@@ -85,7 +85,7 @@ static void free_dev_ring(PCIDevice *pci_dev, PvrdmaRing *ring,
     rdma_pci_dma_unmap(pci_dev, ring_state, TARGET_PAGE_SIZE);
 }
 
-static int init_dev_ring(PvrdmaRing *ring, struct pvrdma_ring **ring_state,
+static int init_dev_ring(PvrdmaRing *ring, PvrdmaRingState **ring_state,
                          const char *name, PCIDevice *pci_dev,
                          dma_addr_t dir_addr, uint32_t num_pages)
 {
@@ -114,7 +114,7 @@ static int init_dev_ring(PvrdmaRing *ring, struct pvrdma_ring **ring_state,
     /* RX ring is the second */
     (*ring_state)++;
     rc = pvrdma_ring_init(ring, name, pci_dev,
-                          (struct pvrdma_ring *)*ring_state,
+                          (PvrdmaRingState *)*ring_state,
                           (num_pages - 1) * TARGET_PAGE_SIZE /
                           sizeof(struct pvrdma_cqne),
                           sizeof(struct pvrdma_cqne),
diff --git a/hw/virtio/virtio-net-pci.c b/hw/virtio/virtio-net-pci.c
index 292d13d278..aa0b3caecb 100644
--- a/hw/virtio/virtio-net-pci.c
+++ b/hw/virtio/virtio-net-pci.c
@@ -41,7 +41,8 @@ struct VirtIONetPCI {
 static Property virtio_net_properties[] = {
     DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
-    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3),
+    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
+                       DEV_NVECTORS_UNSPECIFIED),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -50,6 +51,13 @@ static void virtio_net_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     DeviceState *qdev = DEVICE(vpci_dev);
     VirtIONetPCI *dev = VIRTIO_NET_PCI(vpci_dev);
     DeviceState *vdev = DEVICE(&dev->vdev);
+    VirtIONet *net = VIRTIO_NET(vdev);
+
+    if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
+        vpci_dev->nvectors = 2 * MAX(net->nic_conf.peers.queues, 1)
+            + 1 /* Config interrupt */
+            + 1 /* Control vq */;
+    }
 
     virtio_net_set_netclient_name(&dev->vdev, qdev->id,
                                   object_get_typename(OBJECT(qdev)));
diff --git a/include/net/net.h b/include/net/net.h
index 919facaad2..a02949f6db 100644
--- a/include/net/net.h
+++ b/include/net/net.h
@@ -5,6 +5,8 @@
 #include "qapi/qapi-types-net.h"
 #include "net/queue.h"
 #include "hw/qdev-properties-system.h"
+#include "qapi/clone-visitor.h"
+#include "qapi/qapi-visit-net.h"
 
 #define MAC_FMT "%02X:%02X:%02X:%02X:%02X:%02X"
 #define MAC_ARG(x) ((uint8_t *)(x))[0], ((uint8_t *)(x))[1], \
@@ -92,7 +94,8 @@ struct NetClientState {
     NetQueue *incoming_queue;
     char *model;
     char *name;
-    char info_str[256];
+    char *info_str;
+    NetdevInfo *stored_config;
     unsigned receive_disabled : 1;
     NetClientDestructor *destructor;
     unsigned int queue_index;
@@ -144,12 +147,17 @@ void *qemu_get_nic_opaque(NetClientState *nc);
 void qemu_del_net_client(NetClientState *nc);
 typedef void (*qemu_nic_foreach)(NICState *nic, void *opaque);
 void qemu_foreach_nic(qemu_nic_foreach func, void *opaque);
+int qemu_can_receive_packet(NetClientState *nc);
 int qemu_can_send_packet(NetClientState *nc);
 ssize_t qemu_sendv_packet(NetClientState *nc, const struct iovec *iov,
                           int iovcnt);
 ssize_t qemu_sendv_packet_async(NetClientState *nc, const struct iovec *iov,
                                 int iovcnt, NetPacketSent *sent_cb);
 ssize_t qemu_send_packet(NetClientState *nc, const uint8_t *buf, int size);
+ssize_t qemu_receive_packet(NetClientState *nc, const uint8_t *buf, int size);
+ssize_t qemu_receive_packet_iov(NetClientState *nc,
+                                const struct iovec *iov,
+                                int iovcnt);
 ssize_t qemu_send_packet_raw(NetClientState *nc, const uint8_t *buf, int size);
 ssize_t qemu_send_packet_async(NetClientState *nc, const uint8_t *buf,
                                int size, NetPacketSent *sent_cb);
diff --git a/include/net/queue.h b/include/net/queue.h
index c0269bb1dc..9f2f289d77 100644
--- a/include/net/queue.h
+++ b/include/net/queue.h
@@ -55,6 +55,14 @@ void qemu_net_queue_append_iov(NetQueue *queue,
 
 void qemu_del_net_queue(NetQueue *queue);
 
+ssize_t qemu_net_queue_receive(NetQueue *queue,
+                               const uint8_t *data,
+                               size_t size);
+
+ssize_t qemu_net_queue_receive_iov(NetQueue *queue,
+                                   const struct iovec *iov,
+                                   int iovcnt);
+
 ssize_t qemu_net_queue_send(NetQueue *queue,
                             NetClientState *sender,
                             unsigned flags,
diff --git a/include/qapi/hmp-output-visitor.h b/include/qapi/hmp-output-visitor.h
new file mode 100644
index 0000000000..541e4002e3
--- /dev/null
+++ b/include/qapi/hmp-output-visitor.h
@@ -0,0 +1,30 @@
+/*
+ * HMP string output Visitor
+ *
+ * Copyright Yandex N.V., 2021
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef HMP_OUTPUT_VISITOR_H
+#define HMP_OUTPUT_VISITOR_H
+
+#include "qapi/visitor.h"
+
+typedef struct HMPOutputVisitor HMPOutputVisitor;
+
+/**
+ * Create a HMP string output visitor for @obj
+ *
+ * Flattens dicts/structures, only shows arrays borders.
+ *
+ * Errors are not expected to happen.
+ *
+ * The caller is responsible for freeing the visitor with
+ * visit_free().
+ */
+Visitor *hmp_output_visitor_new(char **result);
+
+#endif
diff --git a/include/standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h b/include/standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h
deleted file mode 100644
index 7b4062a1a1..0000000000
--- a/include/standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h
+++ /dev/null
@@ -1,114 +0,0 @@
-/*
- * Copyright (c) 2012-2016 VMware, Inc.  All rights reserved.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of EITHER the GNU General Public License
- * version 2 as published by the Free Software Foundation or the BSD
- * 2-Clause License. This program is distributed in the hope that it
- * will be useful, but WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED
- * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License version 2 for more details at
- * http://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program available in the file COPYING in the main
- * directory of this source tree.
- *
- * The BSD 2-Clause License
- *
- *     Redistribution and use in source and binary forms, with or
- *     without modification, are permitted provided that the following
- *     conditions are met:
- *
- *      - Redistributions of source code must retain the above
- *        copyright notice, this list of conditions and the following
- *        disclaimer.
- *
- *      - Redistributions in binary form must reproduce the above
- *        copyright notice, this list of conditions and the following
- *        disclaimer in the documentation and/or other materials
- *        provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
- * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
- * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
- * OF THE POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef __PVRDMA_RING_H__
-#define __PVRDMA_RING_H__
-
-#include "standard-headers/linux/types.h"
-
-#define PVRDMA_INVALID_IDX	-1	/* Invalid index. */
-
-struct pvrdma_ring {
-	int prod_tail;	/* Producer tail. */
-	int cons_head;	/* Consumer head. */
-};
-
-struct pvrdma_ring_state {
-	struct pvrdma_ring tx;	/* Tx ring. */
-	struct pvrdma_ring rx;	/* Rx ring. */
-};
-
-static inline int pvrdma_idx_valid(uint32_t idx, uint32_t max_elems)
-{
-	/* Generates fewer instructions than a less-than. */
-	return (idx & ~((max_elems << 1) - 1)) == 0;
-}
-
-static inline int32_t pvrdma_idx(int *var, uint32_t max_elems)
-{
-	const unsigned int idx = qatomic_read(var);
-
-	if (pvrdma_idx_valid(idx, max_elems))
-		return idx & (max_elems - 1);
-	return PVRDMA_INVALID_IDX;
-}
-
-static inline void pvrdma_idx_ring_inc(int *var, uint32_t max_elems)
-{
-	uint32_t idx = qatomic_read(var) + 1;	/* Increment. */
-
-	idx &= (max_elems << 1) - 1;		/* Modulo size, flip gen. */
-	qatomic_set(var, idx);
-}
-
-static inline int32_t pvrdma_idx_ring_has_space(const struct pvrdma_ring *r,
-					      uint32_t max_elems, uint32_t *out_tail)
-{
-	const uint32_t tail = qatomic_read(&r->prod_tail);
-	const uint32_t head = qatomic_read(&r->cons_head);
-
-	if (pvrdma_idx_valid(tail, max_elems) &&
-	    pvrdma_idx_valid(head, max_elems)) {
-		*out_tail = tail & (max_elems - 1);
-		return tail != (head ^ max_elems);
-	}
-	return PVRDMA_INVALID_IDX;
-}
-
-static inline int32_t pvrdma_idx_ring_has_data(const struct pvrdma_ring *r,
-					     uint32_t max_elems, uint32_t *out_head)
-{
-	const uint32_t tail = qatomic_read(&r->prod_tail);
-	const uint32_t head = qatomic_read(&r->cons_head);
-
-	if (pvrdma_idx_valid(tail, max_elems) &&
-	    pvrdma_idx_valid(head, max_elems)) {
-		*out_head = head & (max_elems - 1);
-		return tail != head;
-	}
-	return PVRDMA_INVALID_IDX;
-}
-
-#endif /* __PVRDMA_RING_H__ */
diff --git a/net/l2tpv3.c b/net/l2tpv3.c
index e4d4218db6..b7e1d84674 100644
--- a/net/l2tpv3.c
+++ b/net/l2tpv3.c
@@ -723,8 +723,12 @@ int net_init_l2tpv3(const Netdev *netdev,
 
     l2tpv3_read_poll(s, true);
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "l2tpv3: connected");
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_L2TPV3;
+
+    QAPI_CLONE_MEMBERS(NetdevL2TPv3Options,
+                       &nc->stored_config->u.l2tpv3, l2tpv3);
     return 0;
 outerr:
     qemu_del_net_client(nc);
diff --git a/net/net.c b/net/net.c
index 9a2a4c99a5..725a4e1450 100644
--- a/net/net.c
+++ b/net/net.c
@@ -23,6 +23,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu-common.h"
 
 #include "net/net.h"
 #include "clients.h"
@@ -35,7 +36,6 @@
 #include "monitor/monitor.h"
 #include "qemu/help_option.h"
 #include "qapi/qapi-commands-net.h"
-#include "qapi/qapi-visit-net.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qerror.h"
 #include "qemu/error-report.h"
@@ -55,6 +55,7 @@
 #include "sysemu/sysemu.h"
 #include "net/filter.h"
 #include "qapi/string-output-visitor.h"
+#include "qapi/hmp-output-visitor.h"
 
 /* Net bridge is currently not supported for W32. */
 #if !defined(_WIN32)
@@ -129,11 +130,12 @@ char *qemu_mac_strdup_printf(const uint8_t *macaddr)
 
 void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6])
 {
-    snprintf(nc->info_str, sizeof(nc->info_str),
-             "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
-             nc->model,
-             macaddr[0], macaddr[1], macaddr[2],
-             macaddr[3], macaddr[4], macaddr[5]);
+    g_free(nc->info_str);
+    nc->info_str = g_strdup_printf(
+        "model=%s,macaddr=%02x:%02x:%02x:%02x:%02x:%02x",
+        nc->model,
+        macaddr[0], macaddr[1], macaddr[2],
+        macaddr[3], macaddr[4], macaddr[5]);
 }
 
 static int mac_table[256] = {0};
@@ -352,6 +354,8 @@ static void qemu_free_net_client(NetClientState *nc)
     }
     g_free(nc->name);
     g_free(nc->model);
+    g_free(nc->info_str);
+    qapi_free_NetdevInfo(nc->stored_config);
     if (nc->destructor) {
         nc->destructor(nc);
     }
@@ -528,6 +532,17 @@ int qemu_set_vnet_be(NetClientState *nc, bool is_be)
 #endif
 }
 
+int qemu_can_receive_packet(NetClientState *nc)
+{
+    if (nc->receive_disabled) {
+        return 0;
+    } else if (nc->info->can_receive &&
+               !nc->info->can_receive(nc)) {
+        return 0;
+    }
+    return 1;
+}
+
 int qemu_can_send_packet(NetClientState *sender)
 {
     int vm_running = runstate_is_running();
@@ -540,13 +555,7 @@ int qemu_can_send_packet(NetClientState *sender)
         return 1;
     }
 
-    if (sender->peer->receive_disabled) {
-        return 0;
-    } else if (sender->peer->info->can_receive &&
-               !sender->peer->info->can_receive(sender->peer)) {
-        return 0;
-    }
-    return 1;
+    return qemu_can_receive_packet(sender->peer);
 }
 
 static ssize_t filter_receive_iov(NetClientState *nc,
@@ -679,6 +688,25 @@ ssize_t qemu_send_packet(NetClientState *nc, const uint8_t *buf, int size)
     return qemu_send_packet_async(nc, buf, size, NULL);
 }
 
+ssize_t qemu_receive_packet(NetClientState *nc, const uint8_t *buf, int size)
+{
+    if (!qemu_can_receive_packet(nc)) {
+        return 0;
+    }
+
+    return qemu_net_queue_receive(nc->incoming_queue, buf, size);
+}
+
+ssize_t qemu_receive_packet_iov(NetClientState *nc, const struct iovec *iov,
+                                int iovcnt)
+{
+    if (!qemu_can_receive_packet(nc)) {
+        return 0;
+    }
+
+    return qemu_net_queue_receive_iov(nc->incoming_queue, iov, iovcnt);
+}
+
 ssize_t qemu_send_packet_raw(NetClientState *nc, const uint8_t *buf, int size)
 {
     return qemu_send_packet_async_with_flags(nc, QEMU_NET_PACKET_FLAG_RAW,
@@ -1133,6 +1161,11 @@ void netdev_add(QemuOpts *opts, Error **errp)
 
 void qmp_netdev_add(Netdev *netdev, Error **errp)
 {
+    if (!id_wellformed(netdev->id)) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE, "id", "an identifier");
+        return;
+    }
+
     net_client_init1(netdev, true, errp);
 }
 
@@ -1189,14 +1222,42 @@ static void netfilter_print_info(Monitor *mon, NetFilterState *nf)
     monitor_printf(mon, "\n");
 }
 
+static char *generate_info_str(NetClientState *nc)
+{
+    NetdevInfo *ni = nc->stored_config;
+    char *ret_out = NULL;
+    Visitor *v;
+
+    /* Use legacy field info_str for NIC and hubports */
+    if ((nc->info->type == NET_CLIENT_DRIVER_NIC) ||
+        (nc->info->type == NET_CLIENT_DRIVER_HUBPORT)) {
+        return g_strdup(nc->info_str ? nc->info_str : "");
+    }
+
+    if (!ni) {
+        return g_malloc0(1);
+    }
+
+    v = hmp_output_visitor_new(&ret_out);
+    if (visit_type_NetdevInfo(v, "", &ni, NULL)) {
+        visit_complete(v, &ret_out);
+    }
+    visit_free(v);
+
+    return ret_out;
+}
+
 void print_net_client(Monitor *mon, NetClientState *nc)
 {
     NetFilterState *nf;
+    char *info_str = generate_info_str(nc);
 
     monitor_printf(mon, "%s: index=%d,type=%s,%s\n", nc->name,
                    nc->queue_index,
                    NetClientDriver_str(nc->info->type),
-                   nc->info_str);
+                   info_str);
+    g_free(info_str);
+
     if (!QTAILQ_EMPTY(&nc->filters)) {
         monitor_printf(mon, "filters:\n");
     }
@@ -1259,6 +1320,34 @@ RxFilterInfoList *qmp_query_rx_filter(bool has_name, const char *name,
     return filter_list;
 }
 
+NetdevInfoList *qmp_query_netdev(Error **errp)
+{
+    NetdevInfoList *list = NULL;
+    NetClientState *nc;
+
+    QTAILQ_FOREACH(nc, &net_clients, next) {
+        /*
+         * Only look at netdevs (backend network devices), not for each queue
+         * or NIC / hubport
+         */
+        if (nc->stored_config) {
+            NetdevInfo *element = QAPI_CLONE(NetdevInfo, nc->stored_config);
+
+            g_free(element->id); /* Need to dealloc empty id after clone */
+            element->id = g_strdup(nc->name);
+
+            element->has_peer_id = nc->peer != NULL;
+            if (element->has_peer_id) {
+                element->peer_id = g_strdup(nc->peer->name);
+            }
+
+            QAPI_LIST_PREPEND(list, element);
+        }
+    }
+
+    return list;
+}
+
 void hmp_info_network(Monitor *mon, const QDict *qdict)
 {
     NetClientState *nc, *peer;
diff --git a/net/netmap.c b/net/netmap.c
index 350f097f91..ad59d4ade4 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -427,6 +427,13 @@ int net_init_netmap(const Netdev *netdev,
     pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
     netmap_read_poll(s, true); /* Initially only poll for reads. */
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_NETMAP;
+
+    QAPI_CLONE_MEMBERS(NetdevNetmapOptions,
+                       &nc->stored_config->u.netmap, netmap_opts);
+
     return 0;
 }
 
diff --git a/net/queue.c b/net/queue.c
index 19e32c80fd..c872d51df8 100644
--- a/net/queue.c
+++ b/net/queue.c
@@ -182,6 +182,28 @@ static ssize_t qemu_net_queue_deliver_iov(NetQueue *queue,
     return ret;
 }
 
+ssize_t qemu_net_queue_receive(NetQueue *queue,
+                               const uint8_t *data,
+                               size_t size)
+{
+    if (queue->delivering) {
+        return 0;
+    }
+
+    return qemu_net_queue_deliver(queue, NULL, 0, data, size);
+}
+
+ssize_t qemu_net_queue_receive_iov(NetQueue *queue,
+                                   const struct iovec *iov,
+                                   int iovcnt)
+{
+    if (queue->delivering) {
+        return 0;
+    }
+
+    return qemu_net_queue_deliver_iov(queue, NULL, 0, iov, iovcnt);
+}
+
 ssize_t qemu_net_queue_send(NetQueue *queue,
                             NetClientState *sender,
                             unsigned flags,
diff --git a/net/slirp.c b/net/slirp.c
index be914c0be0..9454a673d6 100644
--- a/net/slirp.c
+++ b/net/slirp.c
@@ -377,6 +377,9 @@ static int net_slirp_init(NetClientState *peer, const char *model,
     int shift;
     char *end;
     struct slirp_config_str *config;
+    NetdevUserOptions *stored;
+    StringList **stored_hostfwd;
+    StringList **stored_guestfwd;
 
     if (!ipv4 && (vnetwork || vhost || vnameserver)) {
         error_setg(errp, "IPv4 disabled but netmask/host/dns provided");
@@ -552,9 +555,114 @@ static int net_slirp_init(NetClientState *peer, const char *model,
 
     nc = qemu_new_net_client(&net_slirp_info, peer, model, name);
 
-    snprintf(nc->info_str, sizeof(nc->info_str),
-             "net=%s,restrict=%s", inet_ntoa(net),
-             restricted ? "on" : "off");
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_USER;
+    stored = &nc->stored_config->u.user;
+
+    if (vhostname) {
+        stored->has_hostname = true;
+        stored->hostname = g_strdup(vhostname);
+    }
+
+    stored->has_q_restrict = true;
+    stored->q_restrict = restricted;
+
+    stored->has_ipv4 = true;
+    stored->ipv4 = ipv4;
+
+    stored->has_ipv6 = true;
+    stored->ipv6 = ipv6;
+
+    if (ipv4) {
+        uint8_t *net_bytes = (uint8_t *)&net;
+        uint8_t *mask_bytes = (uint8_t *)&mask;
+
+        stored->has_net = true;
+        stored->net = g_strdup_printf("%d.%d.%d.%d/%d.%d.%d.%d",
+                                      net_bytes[0], net_bytes[1],
+                                      net_bytes[2], net_bytes[3],
+                                      mask_bytes[0], mask_bytes[1],
+                                      mask_bytes[2], mask_bytes[3]);
+
+        stored->has_host = true;
+        stored->host = g_strdup(inet_ntoa(host));
+    }
+
+    if (tftp_export) {
+        stored->has_tftp = true;
+        stored->tftp = g_strdup(tftp_export);
+    }
+
+    if (bootfile) {
+        stored->has_bootfile = true;
+        stored->bootfile = g_strdup(bootfile);
+    }
+
+    if (vdhcp_start) {
+        stored->has_dhcpstart = true;
+        stored->dhcpstart = g_strdup(vdhcp_start);
+    }
+
+    if (ipv4) {
+        stored->has_dns = true;
+        stored->dns = g_strdup(inet_ntoa(dns));
+    }
+
+    if (dnssearch) {
+        stored->has_dnssearch = true;
+        StringList **stored_list = &stored->dnssearch;
+
+        for (int i = 0; dnssearch[i]; i++) {
+            String *element = g_new0(String, 1);
+
+            element->str = g_strdup(dnssearch[i]);
+            QAPI_LIST_APPEND(stored_list, element);
+        }
+    }
+
+    if (vdomainname) {
+        stored->has_domainname = true;
+        stored->domainname = g_strdup(vdomainname);
+    }
+
+    if (ipv6) {
+        char addrstr[INET6_ADDRSTRLEN];
+        const char *res;
+
+        stored->has_ipv6_prefix = true;
+        stored->ipv6_prefix = g_strdup(vprefix6);
+
+        stored->has_ipv6_prefixlen = true;
+        stored->ipv6_prefixlen = vprefix6_len;
+
+        res = inet_ntop(AF_INET6, &ip6_host,
+                        addrstr, sizeof(addrstr));
+
+        stored->has_ipv6_host = true;
+        stored->ipv6_host = g_strdup(res);
+
+        res = inet_ntop(AF_INET6, &ip6_dns,
+                        addrstr, sizeof(addrstr));
+
+        stored->has_ipv6_dns = true;
+        stored->ipv6_dns = g_strdup(res);
+    }
+
+    if (smb_export) {
+        stored->has_smb = true;
+        stored->smb = g_strdup(smb_export);
+    }
+
+    if (vsmbserver) {
+        stored->has_smbserver = true;
+        stored->smbserver = g_strdup(vsmbserver);
+    }
+
+    if (tftp_server_name) {
+        stored->has_tftp_server_name = true;
+        stored->tftp_server_name = g_strdup(tftp_server_name);
+    }
 
     s = DO_UPCAST(SlirpState, nc, nc);
 
@@ -581,15 +689,25 @@ static int net_slirp_init(NetClientState *peer, const char *model,
     s->poll_notifier.notify = net_slirp_poll_notify;
     main_loop_poll_add_notifier(&s->poll_notifier);
 
+    stored_hostfwd = &stored->hostfwd;
+    stored_guestfwd = &stored->guestfwd;
+
     for (config = slirp_configs; config; config = config->next) {
+        String *element = g_new0(String, 1);
+
+        element->str = g_strdup(config->str);
         if (config->flags & SLIRP_CFG_HOSTFWD) {
             if (slirp_hostfwd(s, config->str, errp) < 0) {
                 goto error;
             }
+            stored->has_hostfwd = true;
+            QAPI_LIST_APPEND(stored_hostfwd, element);
         } else {
             if (slirp_guestfwd(s, config->str, errp) < 0) {
                 goto error;
             }
+            stored->has_guestfwd = true;
+            QAPI_LIST_APPEND(stored_guestfwd, element);
         }
     }
 #ifndef _WIN32
diff --git a/net/socket.c b/net/socket.c
index 15b410e8d8..c0de10c0c0 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -180,7 +180,6 @@ static void net_socket_send(void *opaque)
         s->fd = -1;
         net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
         s->nc.link_down = true;
-        memset(s->nc.info_str, 0, sizeof(s->nc.info_str));
 
         return;
     }
@@ -342,6 +341,7 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
     NetSocketState *s;
     SocketAddress *sa;
     SocketAddressType sa_type;
+    NetdevSocketOptions *stored;
 
     sa = socket_local_address(fd, errp);
     if (!sa) {
@@ -385,19 +385,24 @@ static NetSocketState *net_socket_fd_init_dgram(NetClientState *peer,
     net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
     net_socket_read_poll(s, true);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
+
     /* mcast: save bound address as dst */
     if (is_connected && mcast != NULL) {
+        stored->has_mcast = true;
+        stored->mcast = g_strdup(mcast);
+
         s->dgram_dst = saddr;
-        snprintf(nc->info_str, sizeof(nc->info_str),
-                 "socket: fd=%d (cloned mcast=%s:%d)",
-                 fd, inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
     } else {
         if (sa_type == SOCKET_ADDRESS_TYPE_UNIX) {
             s->dgram_dst.sin_family = AF_UNIX;
         }
-
-        snprintf(nc->info_str, sizeof(nc->info_str),
-                 "socket: fd=%d %s", fd, SocketAddressType_str(sa_type));
     }
 
     return s;
@@ -428,11 +433,10 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
 {
     NetClientState *nc;
     NetSocketState *s;
+    NetdevSocketOptions *stored;
 
     nc = qemu_new_net_client(&net_socket_info, peer, model, name);
 
-    snprintf(nc->info_str, sizeof(nc->info_str), "socket: fd=%d", fd);
-
     s = DO_UPCAST(NetSocketState, nc, nc);
 
     s->fd = fd;
@@ -447,6 +451,15 @@ static NetSocketState *net_socket_fd_init_stream(NetClientState *peer,
     } else {
         qemu_set_fd_handler(s->fd, NULL, net_socket_connect, s);
     }
+
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
+
     return s;
 }
 
@@ -483,6 +496,7 @@ static void net_socket_accept(void *opaque)
     struct sockaddr_in saddr;
     socklen_t len;
     int fd;
+    NetdevSocketOptions *stored;
 
     for(;;) {
         len = sizeof(saddr);
@@ -498,9 +512,12 @@ static void net_socket_accept(void *opaque)
     s->fd = fd;
     s->nc.link_down = false;
     net_socket_connect(s);
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "socket: connection from %s:%d",
-             inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
+
+    /* Store additional startup parameters (extend net_socket_listen_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_fd = true;
+    stored->fd = g_strdup_printf("%d", fd);
 }
 
 static int net_socket_listen_init(NetClientState *peer,
@@ -513,6 +530,7 @@ static int net_socket_listen_init(NetClientState *peer,
     NetSocketState *s;
     struct sockaddr_in saddr;
     int fd, ret;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -549,6 +567,15 @@ static int net_socket_listen_init(NetClientState *peer,
     net_socket_rs_init(&s->rs, net_socket_rs_finalize, false);
 
     qemu_set_fd_handler(s->listen_fd, net_socket_accept, NULL, s);
+
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_SOCKET;
+    stored = &nc->stored_config->u.socket;
+
+    stored->has_listen = true;
+    stored->listen = g_strdup(host_str);
+
     return 0;
 }
 
@@ -561,6 +588,7 @@ static int net_socket_connect_init(NetClientState *peer,
     NetSocketState *s;
     int fd, connected, ret;
     struct sockaddr_in saddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -598,9 +626,12 @@ static int net_socket_connect_init(NetClientState *peer,
         return -1;
     }
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "socket: connect to %s:%d",
-             inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_connect = true;
+    stored->connect = g_strdup(host_str);
+
     return 0;
 }
 
@@ -615,6 +646,7 @@ static int net_socket_mcast_init(NetClientState *peer,
     int fd;
     struct sockaddr_in saddr;
     struct in_addr localaddr, *param_localaddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&saddr, host_str, errp) < 0) {
         return -1;
@@ -643,11 +675,20 @@ static int net_socket_mcast_init(NetClientState *peer,
 
     s->dgram_dst = saddr;
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "socket: mcast=%s:%d",
-             inet_ntoa(saddr.sin_addr), ntohs(saddr.sin_port));
-    return 0;
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    if (!stored->has_mcast) {
+        stored->has_mcast = true;
+        stored->mcast = g_strdup(host_str);
+    }
 
+    if (localaddr_str) {
+        stored->has_localaddr = true;
+        stored->localaddr = g_strdup(localaddr_str);
+    }
+
+    return 0;
 }
 
 static int net_socket_udp_init(NetClientState *peer,
@@ -660,6 +701,7 @@ static int net_socket_udp_init(NetClientState *peer,
     NetSocketState *s;
     int fd, ret;
     struct sockaddr_in laddr, raddr;
+    NetdevSocketOptions *stored;
 
     if (parse_host_port(&laddr, lhost, errp) < 0) {
         return -1;
@@ -698,9 +740,15 @@ static int net_socket_udp_init(NetClientState *peer,
 
     s->dgram_dst = raddr;
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "socket: udp=%s:%d",
-             inet_ntoa(raddr.sin_addr), ntohs(raddr.sin_port));
+    /* Store additional startup parameters (extend net_socket_fd_init) */
+    stored = &s->nc.stored_config->u.socket;
+
+    stored->has_localaddr = true;
+    stored->localaddr = g_strdup(lhost);
+
+    stored->has_udp = true;
+    stored->udp = g_strdup(rhost);
+
     return 0;
 }
 
diff --git a/net/tap-win32.c b/net/tap-win32.c
index 2b5dcda36e..21e451107b 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -768,6 +768,7 @@ static int tap_win32_init(NetClientState *peer, const char *model,
     NetClientState *nc;
     TAPState *s;
     tap_win32_overlapped_t *handle;
+    NetdevTapOptions *stored;
 
     if (tap_win32_open(&handle, ifname) < 0) {
         printf("tap: Could not open '%s'\n", ifname);
@@ -778,8 +779,13 @@ static int tap_win32_init(NetClientState *peer, const char *model,
 
     s = DO_UPCAST(TAPState, nc, nc);
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-             "tap: ifname=%s", ifname);
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_TAP;
+    stored = &nc->stored_config->u.tap;
+
+    stored->has_ifname = true;
+    stored->ifname = g_strdup(ifname);
 
     s->handle = handle;
 
diff --git a/net/tap.c b/net/tap.c
index b7512853f4..12a08d54fe 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -590,6 +590,7 @@ int net_init_bridge(const Netdev *netdev, const char *name,
     const char *helper, *br;
     TAPState *s;
     int fd, vnet_hdr;
+    NetdevBridgeOptions *stored;
 
     assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
     bridge = &netdev->u.bridge;
@@ -609,8 +610,20 @@ int net_init_bridge(const Netdev *netdev, const char *name,
     }
     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 
-    snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
-             br);
+    /* Store startup parameters */
+    s->nc.stored_config = g_new0(NetdevInfo, 1);
+    s->nc.stored_config->type = NET_BACKEND_BRIDGE;
+    stored = &s->nc.stored_config->u.bridge;
+
+    if (br) {
+        stored->has_br = true;
+        stored->br = g_strdup(br);
+    }
+
+    if (helper) {
+        stored->has_helper = true;
+        stored->helper = g_strdup(helper);
+    }
 
     return 0;
 }
@@ -656,11 +669,13 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
                              const char *model, const char *name,
                              const char *ifname, const char *script,
                              const char *downscript, const char *vhostfdname,
-                             int vnet_hdr, int fd, Error **errp)
+                             int vnet_hdr, int fd, NetdevInfo **common_stored,
+                             Error **errp)
 {
     Error *err = NULL;
     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
     int vhostfd;
+    NetdevTapOptions *stored;
 
     tap_set_sndbuf(s->fd, tap, &err);
     if (err) {
@@ -668,15 +683,59 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         return;
     }
 
+    /* Store startup parameters */
+    if (!*common_stored) {
+        *common_stored = g_new0(NetdevInfo, 1);
+        (*common_stored)->type = NET_BACKEND_TAP;
+        s->nc.stored_config = *common_stored;
+    }
+    stored = &(*common_stored)->u.tap;
+
+    if (tap->has_sndbuf && !stored->has_sndbuf) {
+        stored->has_sndbuf = true;
+        stored->sndbuf = tap->sndbuf;
+    }
+
+    if (vnet_hdr && !stored->has_vnet_hdr) {
+        stored->has_vnet_hdr = true;
+        stored->vnet_hdr = true;
+    }
+
     if (tap->has_fd || tap->has_fds) {
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
+        if (!stored->has_fds) {
+            stored->has_fds = true;
+            stored->fds = g_strdup_printf("%d", fd);
+        } else {
+            char *tmp_s = stored->fds;
+            stored->fds = g_strdup_printf("%s:%d", stored->fds, fd);
+            g_free(tmp_s);
+        }
     } else if (tap->has_helper) {
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
-                 tap->helper);
+        if (!stored->has_helper) {
+            stored->has_helper = true;
+            stored->helper = g_strdup(tap->helper);
+        }
+
+        if (!stored->has_br) {
+            stored->has_br = true;
+            stored->br = tap->has_br ? g_strdup(tap->br) :
+                                       g_strdup(DEFAULT_BRIDGE_INTERFACE);
+        }
     } else {
-        snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-                 "ifname=%s,script=%s,downscript=%s", ifname, script,
-                 downscript);
+        if (ifname && !stored->has_ifname) {
+            stored->has_ifname = true;
+            stored->ifname = g_strdup(ifname);
+        }
+
+        if (script && !stored->has_script) {
+            stored->has_script = true;
+            stored->script = g_strdup(script);
+        }
+
+        if (downscript && !stored->has_downscript) {
+            stored->has_downscript = true;
+            stored->downscript = g_strdup(downscript);
+        }
 
         if (strcmp(downscript, "no") != 0) {
             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
@@ -689,9 +748,20 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
         VhostNetOptions options;
 
+        stored->has_vhost = true;
+        stored->vhost = true;
+
+        if (tap->has_vhostforce && tap->vhostforce) {
+            stored->has_vhostforce = true;
+            stored->vhostforce = true;
+        }
+
         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
         options.net_backend = &s->nc;
         if (tap->has_poll_us) {
+            stored->has_poll_us = true;
+            stored->poll_us = tap->poll_us;
+
             options.busyloop_timeout = tap->poll_us;
         } else {
             options.busyloop_timeout = 0;
@@ -731,6 +801,15 @@ static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
         }
         options.opaque = (void *)(uintptr_t)vhostfd;
 
+        if (!stored->has_vhostfds) {
+            stored->has_vhostfds = true;
+            stored->vhostfds = g_strdup_printf("%d", vhostfd);
+        } else {
+            char *tmp_s = stored->vhostfds;
+            stored->vhostfds = g_strdup_printf("%s:%d", stored->fds, vhostfd);
+            g_free(tmp_s);
+        }
+
         s->vhost_net = vhost_net_init(&options);
         if (!s->vhost_net) {
             if (tap->has_vhostforce && tap->vhostforce) {
@@ -783,6 +862,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
     const char *vhostfdname;
     char ifname[128];
     int ret = 0;
+    NetdevInfo *common_stored = NULL; /* will store configuration */
 
     assert(netdev->type == NET_CLIENT_DRIVER_TAP);
     tap = &netdev->u.tap;
@@ -829,7 +909,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
 
         net_init_tap_one(tap, peer, "tap", name, NULL,
                          script, downscript,
-                         vhostfdname, vnet_hdr, fd, &err);
+                         vhostfdname, vnet_hdr, fd, &common_stored, &err);
         if (err) {
             error_propagate(errp, err);
             close(fd);
@@ -892,7 +972,7 @@ int net_init_tap(const Netdev *netdev, const char *name,
             net_init_tap_one(tap, peer, "tap", name, ifname,
                              script, downscript,
                              tap->has_vhostfds ? vhost_fds[i] : NULL,
-                             vnet_hdr, fd, &err);
+                             vnet_hdr, fd, &common_stored, &err);
             if (err) {
                 error_propagate(errp, err);
                 ret = -1;
@@ -935,7 +1015,7 @@ free_fail:
 
         net_init_tap_one(tap, peer, "bridge", name, ifname,
                          script, downscript, vhostfdname,
-                         vnet_hdr, fd, &err);
+                         vnet_hdr, fd, &common_stored, &err);
         if (err) {
             error_propagate(errp, err);
             close(fd);
@@ -981,7 +1061,8 @@ free_fail:
             net_init_tap_one(tap, peer, "tap", name, ifname,
                              i >= 1 ? "no" : script,
                              i >= 1 ? "no" : downscript,
-                             vhostfdname, vnet_hdr, fd, &err);
+                             vhostfdname, vnet_hdr, fd,
+                             &common_stored, &err);
             if (err) {
                 error_propagate(errp, err);
                 close(fd);
diff --git a/net/vde.c b/net/vde.c
index 99189cccb6..64bdb937ca 100644
--- a/net/vde.c
+++ b/net/vde.c
@@ -84,6 +84,7 @@ static int net_vde_init(NetClientState *peer, const char *model,
     VDECONN *vde;
     char *init_group = (char *)group;
     char *init_sock = (char *)sock;
+    NetdevVdeOptions *stored;
 
     struct vde_open_args args = {
         .port = port,
@@ -99,15 +100,33 @@ static int net_vde_init(NetClientState *peer, const char *model,
 
     nc = qemu_new_net_client(&net_vde_info, peer, model, name);
 
-    snprintf(nc->info_str, sizeof(nc->info_str), "sock=%s,fd=%d",
-             sock, vde_datafd(vde));
-
     s = DO_UPCAST(VDEState, nc, nc);
 
     s->vde = vde;
 
     qemu_set_fd_handler(vde_datafd(s->vde), vde_to_qemu, NULL, s);
 
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_VDE;
+    stored = &nc->stored_config->u.vde;
+
+    if (sock) {
+        stored->has_sock = true;
+        stored->sock = g_strdup(sock);
+    }
+
+    stored->has_port = true;
+    stored->port = port;
+
+    if (group) {
+        stored->has_group = true;
+        stored->group = g_strdup(group);
+    }
+
+    stored->has_mode = true;
+    stored->mode = mode;
+
     return 0;
 }
 
diff --git a/net/vhost-user.c b/net/vhost-user.c
index ffbd94d944..e443c4b2b5 100644
--- a/net/vhost-user.c
+++ b/net/vhost-user.c
@@ -311,14 +311,15 @@ static void net_vhost_user_event(void *opaque, QEMUChrEvent event)
 }
 
 static int net_vhost_user_init(NetClientState *peer, const char *device,
-                               const char *name, Chardev *chr,
-                               int queues)
+                               const char *name, const char *chardev,
+                               Chardev *chr, int queues)
 {
     Error *err = NULL;
     NetClientState *nc, *nc0 = NULL;
     NetVhostUserState *s = NULL;
     VhostUserState *user;
     int i;
+    NetdevVhostUserOptions *stored;
 
     assert(name);
     assert(queues > 0);
@@ -326,8 +327,6 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
     user = g_new0(struct VhostUserState, 1);
     for (i = 0; i < queues; i++) {
         nc = qemu_new_net_client(&net_vhost_user_info, peer, device, name);
-        snprintf(nc->info_str, sizeof(nc->info_str), "vhost-user%d to %s",
-                 i, chr->label);
         nc->queue_index = i;
         if (!nc0) {
             nc0 = nc;
@@ -355,6 +354,16 @@ static int net_vhost_user_init(NetClientState *peer, const char *device,
 
     assert(s->vhost_net);
 
+    /* Store startup parameters */
+    nc0->stored_config = g_new0(NetdevInfo, 1);
+    nc0->stored_config->type = NET_BACKEND_VHOST_USER;
+    stored = &nc0->stored_config->u.vhost_user;
+
+    stored->chardev = g_strdup(chardev);
+
+    stored->has_queues = true;
+    stored->queues = queues;
+
     return 0;
 
 err:
@@ -446,5 +455,6 @@ int net_init_vhost_user(const Netdev *netdev, const char *name,
         return -1;
     }
 
-    return net_vhost_user_init(peer, "vhost_user", name, chr, queues);
+    return net_vhost_user_init(peer, "vhost_user", name,
+                               vhost_user_opts->chardev, chr, queues);
 }
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index fe659ec9e2..5a28bbcd7b 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -184,9 +184,22 @@ static int net_vhost_vdpa_init(NetClientState *peer, const char *device,
     VhostVDPAState *s;
     int vdpa_device_fd = -1;
     int ret = 0;
+    NetdevVhostVDPAOptions *stored;
+
     assert(name);
     nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device, name);
-    snprintf(nc->info_str, sizeof(nc->info_str), TYPE_VHOST_VDPA);
+
+    /* Store startup parameters */
+    nc->stored_config = g_new0(NetdevInfo, 1);
+    nc->stored_config->type = NET_BACKEND_VHOST_VDPA;
+    stored = &nc->stored_config->u.vhost_vdpa;
+
+    stored->has_vhostdev = true;
+    stored->vhostdev = g_strdup(vhostdev);
+
+    stored->has_queues = true;
+    stored->queues = 1; /* TODO: change when support multiqueue */
+
     nc->queue_index = 0;
     s = DO_UPCAST(VhostVDPAState, nc, nc);
     vdpa_device_fd = qemu_open_old(vhostdev, O_RDWR);
diff --git a/qapi/hmp-output-visitor.c b/qapi/hmp-output-visitor.c
new file mode 100644
index 0000000000..8036605f97
--- /dev/null
+++ b/qapi/hmp-output-visitor.c
@@ -0,0 +1,193 @@
+/*
+ * HMP string output Visitor
+ *
+ * Copyright Yandex N.V., 2021
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/cutils.h"
+#include "qapi/hmp-output-visitor.h"
+#include "qapi/visitor-impl.h"
+
+struct HMPOutputVisitor {
+    Visitor visitor;
+    char **result;
+    GString *buffer;
+    bool is_continue;
+};
+
+static HMPOutputVisitor *to_hov(Visitor *v)
+{
+    return container_of(v, HMPOutputVisitor, visitor);
+}
+
+static void hmp_output_append_formatted(Visitor *v, const char *fmt, ...)
+{
+    HMPOutputVisitor *ov = to_hov(v);
+    va_list args;
+
+    if (ov->is_continue) {
+        g_string_append(ov->buffer, ",");
+    } else {
+        ov->is_continue = true;
+    }
+
+    va_start(args, fmt);
+    g_string_append_vprintf(ov->buffer, fmt, args);
+    va_end(args);
+}
+
+static void hmp_output_skip_comma(Visitor *v)
+{
+    HMPOutputVisitor *ov = to_hov(v);
+
+    ov->is_continue = false;
+}
+
+static bool hmp_output_start_struct(Visitor *v, const char *name,
+                                    void **obj, size_t unused, Error **errp)
+{
+    return true;
+}
+
+static void hmp_output_end_struct(Visitor *v, void **obj) {}
+
+static bool hmp_output_start_list(Visitor *v, const char *name,
+                                  GenericList **listp, size_t size,
+                                  Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=[", name);
+    /* First element in array without comma before it */
+    hmp_output_skip_comma(v);
+
+    return true;
+}
+
+static GenericList *hmp_output_next_list(Visitor *v, GenericList *tail,
+                                         size_t size)
+{
+    return tail->next;
+}
+
+static void hmp_output_end_list(Visitor *v, void **obj)
+{
+    /* Don't need comma after last array element */
+    hmp_output_skip_comma(v);
+    hmp_output_append_formatted(v, "]");
+}
+
+static bool hmp_output_type_int64(Visitor *v, const char *name,
+                                  int64_t *obj, Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=%" PRId64, name, *obj);
+
+    return true;
+}
+
+static bool hmp_output_type_uint64(Visitor *v, const char *name,
+                                   uint64_t *obj, Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=%" PRIu64, name, *obj);
+
+    return true;
+}
+
+static bool hmp_output_type_bool(Visitor *v, const char *name, bool *obj,
+                                 Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=%s", name, *obj ? "true" : "false");
+
+    return true;
+}
+
+static bool hmp_output_type_str(Visitor *v, const char *name, char **obj,
+                                Error **errp)
+{
+    /* Skip already printed or unused fields */
+    if (!*obj || g_str_equal(name, "id") || g_str_equal(name, "type")) {
+        return true;
+    }
+
+    /* Do not print stub name for StringList elements */
+    if (g_str_equal(name, "str")) {
+        hmp_output_append_formatted(v, "%s", *obj);
+    } else {
+        hmp_output_append_formatted(v, "%s=%s", name, *obj);
+    }
+
+    return true;
+}
+
+static bool hmp_output_type_number(Visitor *v, const char *name,
+                                   double *obj, Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=%.17g", name, *obj);
+
+    return true;
+}
+
+/* TODO: remove this function? */
+static bool hmp_output_type_any(Visitor *v, const char *name,
+                                QObject **obj, Error **errp)
+{
+    return true;
+}
+
+static bool hmp_output_type_null(Visitor *v, const char *name,
+                                 QNull **obj, Error **errp)
+{
+    hmp_output_append_formatted(v, "%s=NULL", name);
+
+    return true;
+}
+
+static void hmp_output_complete(Visitor *v, void *opaque)
+{
+    HMPOutputVisitor *ov = to_hov(v);
+
+    *ov->result = g_string_free(ov->buffer, false);
+    ov->buffer = NULL;
+}
+
+static void hmp_output_free(Visitor *v)
+{
+    HMPOutputVisitor *ov = to_hov(v);
+
+    if (ov->buffer) {
+        g_string_free(ov->buffer, true);
+    }
+    g_free(v);
+}
+
+Visitor *hmp_output_visitor_new(char **result)
+{
+    HMPOutputVisitor *v;
+
+    v = g_malloc0(sizeof(*v));
+
+    v->visitor.type = VISITOR_OUTPUT;
+    v->visitor.start_struct = hmp_output_start_struct;
+    v->visitor.end_struct = hmp_output_end_struct;
+    v->visitor.start_list = hmp_output_start_list;
+    v->visitor.next_list = hmp_output_next_list;
+    v->visitor.end_list = hmp_output_end_list;
+    v->visitor.type_int64 = hmp_output_type_int64;
+    v->visitor.type_uint64 = hmp_output_type_uint64;
+    v->visitor.type_bool = hmp_output_type_bool;
+    v->visitor.type_str = hmp_output_type_str;
+    v->visitor.type_number = hmp_output_type_number;
+    v->visitor.type_any = hmp_output_type_any;
+    v->visitor.type_null = hmp_output_type_null;
+    v->visitor.complete = hmp_output_complete;
+    v->visitor.free = hmp_output_free;
+
+    v->result = result;
+    v->buffer = g_string_new("");
+    v->is_continue = false;
+
+    return &v->visitor;
+}
diff --git a/qapi/meson.build b/qapi/meson.build
index fcb15a78f1..d4424ae6e7 100644
--- a/qapi/meson.build
+++ b/qapi/meson.build
@@ -8,6 +8,7 @@ util_ss.add(files(
   'qobject-output-visitor.c',
   'string-input-visitor.c',
   'string-output-visitor.c',
+  'hmp-output-visitor.c',
 ))
 if have_system or have_tools
   util_ss.add(files(
diff --git a/qapi/net.json b/qapi/net.json
index c31748c87f..87361ebd9a 100644
--- a/qapi/net.json
+++ b/qapi/net.json
@@ -714,3 +714,83 @@
 ##
 { 'event': 'FAILOVER_NEGOTIATED',
   'data': {'device-id': 'str'} }
+
+##
+# @NetBackend:
+#
+# Available netdev backend drivers.
+#
+# Since: 6.0
+##
+{ 'enum': 'NetBackend',
+  'data': [ 'bridge', 'l2tpv3', 'netmap', 'socket', 'tap', 'user', 'vde',
+            'vhost-user', 'vhost-vdpa' ] }
+
+##
+# @NetdevInfo:
+#
+# Configuration of a network backend device (netdev).
+#
+# @id: Device identifier.
+#
+# @type: Specify the driver used for interpreting remaining arguments.
+#
+# @peer-id: The connected frontend network device name (absent if no frontend
+#           is connected).
+#
+# Since: 6.0
+##
+{ 'union': 'NetdevInfo',
+  'base': { 'id': 'str',
+            'type': 'NetBackend',
+            '*peer-id': 'str' },
+  'discriminator': 'type',
+  'data': {
+      'bridge':     'NetdevBridgeOptions',
+      'l2tpv3':     'NetdevL2TPv3Options',
+      'netmap':     'NetdevNetmapOptions',
+      'socket':     'NetdevSocketOptions',
+      'tap':        'NetdevTapOptions',
+      'user':       'NetdevUserOptions',
+      'vde':        'NetdevVdeOptions',
+      'vhost-user': 'NetdevVhostUserOptions',
+      'vhost-vdpa': 'NetdevVhostVDPAOptions' } }
+
+##
+# @query-netdev:
+#
+# Get a list of @NetdevInfo for all virtual network backend devices (netdevs).
+#
+# Returns: a list of @NetdevInfo describing each netdev.
+#
+# Since: 6.0
+#
+# Example:
+#
+# -> { "execute": "query-netdev" }
+# <- { "return": [
+#          {
+#              "ipv6": true,
+#              "ipv4": true,
+#              "host": "10.0.2.2",
+#              "ipv6-dns": "fec0::3",
+#              "ipv6-prefix": "fec0::",
+#              "net": "10.0.2.0/255.255.255.0",
+#              "ipv6-host": "fec0::2",
+#              "type": "user",
+#              "peer-id": "net0",
+#              "dns": "10.0.2.3",
+#              "hostfwd": [
+#                  {
+#                      "str": "tcp::20004-:22"
+#                  }
+#              ],
+#              "ipv6-prefixlen": 64,
+#              "id": "netdev0",
+#              "restrict": false
+#          }
+#      ]
+#    }
+#
+##
+{ 'command': 'query-netdev', 'returns': ['NetdevInfo'] }
diff --git a/scripts/update-linux-headers.sh b/scripts/update-linux-headers.sh
index fa6f2b6272..1050e36169 100755
--- a/scripts/update-linux-headers.sh
+++ b/scripts/update-linux-headers.sh
@@ -215,8 +215,7 @@ sed  -e '1h;2,$H;$!d;g'  -e 's/[^};]*pvrdma[^(| ]*([^)]*);//g' \
     "$linux/drivers/infiniband/hw/vmw_pvrdma/pvrdma_verbs.h" > \
     "$tmp_pvrdma_verbs";
 
-for i in "$linux/drivers/infiniband/hw/vmw_pvrdma/pvrdma_ring.h" \
-         "$linux/drivers/infiniband/hw/vmw_pvrdma/pvrdma_dev_api.h" \
+for i in "$linux/drivers/infiniband/hw/vmw_pvrdma/pvrdma_dev_api.h" \
          "$tmp_pvrdma_verbs"; do \
     cp_portable "$i" \
          "$output/include/standard-headers/drivers/infiniband/hw/vmw_pvrdma/"
diff --git a/tests/qtest/meson.build b/tests/qtest/meson.build
index 2688e1bfad..66ee9fbf45 100644
--- a/tests/qtest/meson.build
+++ b/tests/qtest/meson.build
@@ -30,6 +30,9 @@ qtests_generic = [
 if config_host.has_key('CONFIG_MODULES')
   qtests_generic += [ 'modules-test' ]
 endif
+if slirp.found()
+  qtests_generic += [ 'test-query-netdev' ]
+endif
 
 qtests_pci = \
   (config_all_devices.has_key('CONFIG_VGA') ? ['display-vga-test'] : []) +                  \
diff --git a/tests/qtest/test-query-netdev.c b/tests/qtest/test-query-netdev.c
new file mode 100644
index 0000000000..1118537a9f
--- /dev/null
+++ b/tests/qtest/test-query-netdev.c
@@ -0,0 +1,120 @@
+/*
+ * QTest testcase for the query-netdev
+ *
+ * Copyright Yandex N.V., 2019
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu/osdep.h"
+
+#include "libqos/libqtest.h"
+#include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qlist.h"
+
+/*
+ * Events can get in the way of responses we are actually waiting for.
+ */
+GCC_FMT_ATTR(2, 3)
+static QObject *wait_command(QTestState *who, const char *command, ...)
+{
+    va_list ap;
+    QDict *response;
+    QObject *result;
+
+    va_start(ap, command);
+    qtest_qmp_vsend(who, command, ap);
+    va_end(ap);
+
+    response = qtest_qmp_receive(who);
+
+    result = qdict_get(response, "return");
+    g_assert(result);
+    qobject_ref(result);
+    qobject_unref(response);
+
+    return result;
+}
+
+static void qmp_query_netdev_no_error(QTestState *qts, size_t netdevs_count)
+{
+    QObject *resp;
+    QList *netdevs;
+
+    resp = wait_command(qts, "{'execute': 'query-netdev'}");
+
+    netdevs = qobject_to(QList, resp);
+    g_assert(netdevs);
+    g_assert(qlist_size(netdevs) == netdevs_count);
+
+    qobject_unref(resp);
+}
+
+static void test_query_netdev(void)
+{
+    const char *arch = qtest_get_arch();
+    QObject *resp;
+    QTestState *state;
+
+    /* Choosing machine for platforms without default one */
+    if (g_str_equal(arch, "arm") ||
+        g_str_equal(arch, "aarch64")) {
+        state = qtest_init(
+            "-nodefaults "
+            "-M virt "
+            "-netdev user,id=slirp0");
+    } else if (g_str_equal(arch, "tricore")) {
+        state = qtest_init(
+            "-nodefaults "
+            "-M tricore_testboard "
+            "-netdev user,id=slirp0");
+    } else if (g_str_equal(arch, "avr")) {
+        state = qtest_init(
+            "-nodefaults "
+            "-M mega2560 "
+            "-netdev user,id=slirp0");
+    } else if (g_str_equal(arch, "rx")) {
+        state = qtest_init(
+            "-nodefaults "
+            "-M gdbsim-r5f562n8 "
+            "-netdev user,id=slirp0");
+    } else {
+        state = qtest_init(
+            "-nodefaults "
+            "-netdev user,id=slirp0");
+    }
+    g_assert(state);
+
+    qmp_query_netdev_no_error(state, 1);
+
+    resp = wait_command(state,
+        "{'execute': 'netdev_add', 'arguments': {"
+        " 'id': 'slirp1',"
+        " 'type': 'user'}}");
+    qobject_unref(resp);
+
+    qmp_query_netdev_no_error(state, 2);
+
+    resp = wait_command(state,
+        "{'execute': 'netdev_del', 'arguments': {"
+        " 'id': 'slirp1'}}");
+    qobject_unref(resp);
+
+    qmp_query_netdev_no_error(state, 1);
+
+    qtest_quit(state);
+}
+
+int main(int argc, char **argv)
+{
+    int ret = 0;
+    g_test_init(&argc, &argv, NULL);
+
+    qtest_add_func("/net/qapi/query_netdev", test_query_netdev);
+
+    ret = g_test_run();
+
+    return ret;
+}