Merge remote-tracking branch 'remotes/mst/tags/for_upstream' into staging

pc, pci, virtio: cleanups, fixes

a bunch of bugfixes and a couple of cleanups
making these easier and/or making debugging easier

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

# gpg: Signature made Fri 29 Jul 2016 04:11:01 BST
# gpg:                using RSA key 0x281F0DB8D28D5469
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>"
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>"
# Primary key fingerprint: 0270 606B 6F3C DF3D 0B17  0970 C350 3912 AFBE 8E67
#      Subkey fingerprint: 5D09 FD08 71C8 F85B 94CA  8A0D 281F 0DB8 D28D 5469

* remotes/mst/tags/for_upstream: (41 commits)
  mptsas: Fix a migration compatible issue
  vhost: do not update last avail idx on get_vring_base() failure
  vhost: add vhost_net_set_backend()
  vhost-user: add error report in vhost_user_write()
  tests: fix vhost-user-test leak
  tests: plug some leaks in virtio-net-test
  vhost-user: wait until backend init is completed
  char: add and use tcp_chr_wait_connected
  char: add chr_wait_connected callback
  vhost: add assert() to check runtime behaviour
  vhost-net: vhost_migration_done is vhost-user specific
  Revert "vhost-net: do not crash if backend is not present"
  vhost-user: add get_vhost_net() assertions
  vhost-user: keep vhost_net after a disconnection
  vhost-user: check vhost_user_{read,write}() return value
  vhost-user: check qemu_chr_fe_set_msgfds() return value
  vhost-user: call set_msgfds unconditionally
  qemu-char: fix qemu_chr_fe_set_msgfds() crash when disconnected
  vhost: use error_report() instead of fprintf(stderr,...)
  vhost: add missing VHOST_OPS_DEBUG
  ...

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

15 files changed, 350 insertions, 200 deletions

diff --git a/hw/display/virtio-gpu-pci.c b/hw/display/virtio-gpu-pci.c
index a71b230d33..34a724c754 100644
--- a/hw/display/virtio-gpu-pci.c
+++ b/hw/display/virtio-gpu-pci.c
@@ -30,9 +30,7 @@ static void virtio_gpu_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     int i;
 
     qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
-    /* force virtio-1.0 */
-    vpci_dev->flags &= ~VIRTIO_PCI_FLAG_DISABLE_MODERN;
-    vpci_dev->flags |= VIRTIO_PCI_FLAG_DISABLE_LEGACY;
+    virtio_pci_force_virtio_1(vpci_dev);
     object_property_set_bool(OBJECT(vdev), true, "realized", errp);
 
     for (i = 0; i < g->conf.max_outputs; i++) {
diff --git a/hw/display/virtio-vga.c b/hw/display/virtio-vga.c
index 315b7fc58c..5b510a17fd 100644
--- a/hw/display/virtio-vga.c
+++ b/hw/display/virtio-vga.c
@@ -134,9 +134,7 @@ static void virtio_vga_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
 
     /* init virtio bits */
     qdev_set_parent_bus(DEVICE(g), BUS(&vpci_dev->bus));
-    /* force virtio-1.0 */
-    vpci_dev->flags &= ~VIRTIO_PCI_FLAG_DISABLE_MODERN;
-    vpci_dev->flags |= VIRTIO_PCI_FLAG_DISABLE_LEGACY;
+    virtio_pci_force_virtio_1(vpci_dev);
     object_property_set_bool(OBJECT(g), true, "realized", &err);
     if (err) {
         error_propagate(errp, err);
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 77c40d92e2..a26a4bb03f 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -600,6 +600,10 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
         QLIST_FOREACH(sec, &bus->child, sibling) {
             int32_t devfn = sec->parent_dev->devfn;
 
+            if (pci_bus_is_root(sec) || pci_bus_is_express(sec)) {
+                continue;
+            }
+
             aml_append(method, aml_name("^S%.02X.PCNT", devfn));
         }
     }
@@ -747,6 +751,27 @@ static void crs_range_free(gpointer data)
     g_free(entry);
 }
 
+typedef struct CrsRangeSet {
+    GPtrArray *io_ranges;
+    GPtrArray *mem_ranges;
+    GPtrArray *mem_64bit_ranges;
+ } CrsRangeSet;
+
+static void crs_range_set_init(CrsRangeSet *range_set)
+{
+    range_set->io_ranges = g_ptr_array_new_with_free_func(crs_range_free);
+    range_set->mem_ranges = g_ptr_array_new_with_free_func(crs_range_free);
+    range_set->mem_64bit_ranges =
+            g_ptr_array_new_with_free_func(crs_range_free);
+}
+
+static void crs_range_set_free(CrsRangeSet *range_set)
+{
+    g_ptr_array_free(range_set->io_ranges, true);
+    g_ptr_array_free(range_set->mem_ranges, true);
+    g_ptr_array_free(range_set->mem_64bit_ranges, true);
+}
+
 static gint crs_range_compare(gconstpointer a, gconstpointer b)
 {
      CrsRangeEntry *entry_a = *(CrsRangeEntry **)a;
@@ -831,18 +856,17 @@ static void crs_range_merge(GPtrArray *range)
     g_ptr_array_free(tmp, true);
 }
 
-static Aml *build_crs(PCIHostState *host,
-                      GPtrArray *io_ranges, GPtrArray *mem_ranges)
+static Aml *build_crs(PCIHostState *host, CrsRangeSet *range_set)
 {
     Aml *crs = aml_resource_template();
-    GPtrArray *host_io_ranges = g_ptr_array_new_with_free_func(crs_range_free);
-    GPtrArray *host_mem_ranges = g_ptr_array_new_with_free_func(crs_range_free);
+    CrsRangeSet temp_range_set;
     CrsRangeEntry *entry;
     uint8_t max_bus = pci_bus_num(host->bus);
     uint8_t type;
     int devfn;
     int i;
 
+    crs_range_set_init(&temp_range_set);
     for (devfn = 0; devfn < ARRAY_SIZE(host->bus->devices); devfn++) {
         uint64_t range_base, range_limit;
         PCIDevice *dev = host->bus->devices[devfn];
@@ -866,9 +890,11 @@ static Aml *build_crs(PCIHostState *host,
             }
 
             if (r->type & PCI_BASE_ADDRESS_SPACE_IO) {
-                crs_range_insert(host_io_ranges, range_base, range_limit);
+                crs_range_insert(temp_range_set.io_ranges,
+                                 range_base, range_limit);
             } else { /* "memory" */
-                crs_range_insert(host_mem_ranges, range_base, range_limit);
+                crs_range_insert(temp_range_set.mem_ranges,
+                                 range_base, range_limit);
             }
         }
 
@@ -887,7 +913,8 @@ static Aml *build_crs(PCIHostState *host,
              * that do not support multiple root buses
              */
             if (range_base && range_base <= range_limit) {
-                crs_range_insert(host_io_ranges, range_base, range_limit);
+                crs_range_insert(temp_range_set.io_ranges,
+                                 range_base, range_limit);
             }
 
             range_base =
@@ -900,7 +927,14 @@ static Aml *build_crs(PCIHostState *host,
              * that do not support multiple root buses
              */
             if (range_base && range_base <= range_limit) {
-                crs_range_insert(host_mem_ranges, range_base, range_limit);
+                uint64_t length = range_limit - range_base + 1;
+                if (range_limit <= UINT32_MAX && length <= UINT32_MAX) {
+                    crs_range_insert(temp_range_set.mem_ranges,
+                                     range_base, range_limit);
+                } else {
+                    crs_range_insert(temp_range_set.mem_64bit_ranges,
+                                     range_base, range_limit);
+                }
             }
 
             range_base =
@@ -913,35 +947,55 @@ static Aml *build_crs(PCIHostState *host,
              * that do not support multiple root buses
              */
             if (range_base && range_base <= range_limit) {
-                crs_range_insert(host_mem_ranges, range_base, range_limit);
+                uint64_t length = range_limit - range_base + 1;
+                if (range_limit <= UINT32_MAX && length <= UINT32_MAX) {
+                    crs_range_insert(temp_range_set.mem_ranges,
+                                     range_base, range_limit);
+                } else {
+                    crs_range_insert(temp_range_set.mem_64bit_ranges,
+                                     range_base, range_limit);
+                }
             }
         }
     }
 
-    crs_range_merge(host_io_ranges);
-    for (i = 0; i < host_io_ranges->len; i++) {
-        entry = g_ptr_array_index(host_io_ranges, i);
+    crs_range_merge(temp_range_set.io_ranges);
+    for (i = 0; i < temp_range_set.io_ranges->len; i++) {
+        entry = g_ptr_array_index(temp_range_set.io_ranges, i);
         aml_append(crs,
                    aml_word_io(AML_MIN_FIXED, AML_MAX_FIXED,
                                AML_POS_DECODE, AML_ENTIRE_RANGE,
                                0, entry->base, entry->limit, 0,
                                entry->limit - entry->base + 1));
-        crs_range_insert(io_ranges, entry->base, entry->limit);
+        crs_range_insert(range_set->io_ranges, entry->base, entry->limit);
     }
-    g_ptr_array_free(host_io_ranges, true);
 
-    crs_range_merge(host_mem_ranges);
-    for (i = 0; i < host_mem_ranges->len; i++) {
-        entry = g_ptr_array_index(host_mem_ranges, i);
+    crs_range_merge(temp_range_set.mem_ranges);
+    for (i = 0; i < temp_range_set.mem_ranges->len; i++) {
+        entry = g_ptr_array_index(temp_range_set.mem_ranges, i);
         aml_append(crs,
                    aml_dword_memory(AML_POS_DECODE, AML_MIN_FIXED,
                                     AML_MAX_FIXED, AML_NON_CACHEABLE,
                                     AML_READ_WRITE,
                                     0, entry->base, entry->limit, 0,
                                     entry->limit - entry->base + 1));
-        crs_range_insert(mem_ranges, entry->base, entry->limit);
+        crs_range_insert(range_set->mem_ranges, entry->base, entry->limit);
     }
-    g_ptr_array_free(host_mem_ranges, true);
+
+    crs_range_merge(temp_range_set.mem_64bit_ranges);
+    for (i = 0; i < temp_range_set.mem_64bit_ranges->len; i++) {
+        entry = g_ptr_array_index(temp_range_set.mem_64bit_ranges, i);
+        aml_append(crs,
+                   aml_qword_memory(AML_POS_DECODE, AML_MIN_FIXED,
+                                    AML_MAX_FIXED, AML_NON_CACHEABLE,
+                                    AML_READ_WRITE,
+                                    0, entry->base, entry->limit, 0,
+                                    entry->limit - entry->base + 1));
+        crs_range_insert(range_set->mem_64bit_ranges,
+                         entry->base, entry->limit);
+    }
+
+    crs_range_set_free(&temp_range_set);
 
     aml_append(crs,
         aml_word_bus_number(AML_MIN_FIXED, AML_MAX_FIXED, AML_POS_DECODE,
@@ -1898,8 +1952,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
 {
     CrsRangeEntry *entry;
     Aml *dsdt, *sb_scope, *scope, *dev, *method, *field, *pkg, *crs;
-    GPtrArray *mem_ranges = g_ptr_array_new_with_free_func(crs_range_free);
-    GPtrArray *io_ranges = g_ptr_array_new_with_free_func(crs_range_free);
+    CrsRangeSet crs_range_set;
     PCMachineState *pcms = PC_MACHINE(machine);
     PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(machine);
     uint32_t nr_mem = machine->ram_slots;
@@ -1988,6 +2041,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     }
     aml_append(dsdt, scope);
 
+    crs_range_set_init(&crs_range_set);
     bus = PC_MACHINE(machine)->bus;
     if (bus) {
         QLIST_FOREACH(bus, &bus->child, sibling) {
@@ -2014,8 +2068,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
             }
 
             aml_append(dev, build_prt(false));
-            crs = build_crs(PCI_HOST_BRIDGE(BUS(bus)->parent),
-                            io_ranges, mem_ranges);
+            crs = build_crs(PCI_HOST_BRIDGE(BUS(bus)->parent), &crs_range_set);
             aml_append(dev, aml_name_decl("_CRS", crs));
             aml_append(scope, dev);
             aml_append(dsdt, scope);
@@ -2036,9 +2089,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
                     AML_POS_DECODE, AML_ENTIRE_RANGE,
                     0x0000, 0x0000, 0x0CF7, 0x0000, 0x0CF8));
 
-    crs_replace_with_free_ranges(io_ranges, 0x0D00, 0xFFFF);
-    for (i = 0; i < io_ranges->len; i++) {
-        entry = g_ptr_array_index(io_ranges, i);
+    crs_replace_with_free_ranges(crs_range_set.io_ranges, 0x0D00, 0xFFFF);
+    for (i = 0; i < crs_range_set.io_ranges->len; i++) {
+        entry = g_ptr_array_index(crs_range_set.io_ranges, i);
         aml_append(crs,
             aml_word_io(AML_MIN_FIXED, AML_MAX_FIXED,
                         AML_POS_DECODE, AML_ENTIRE_RANGE,
@@ -2051,11 +2104,11 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
                          AML_CACHEABLE, AML_READ_WRITE,
                          0, 0x000A0000, 0x000BFFFF, 0, 0x00020000));
 
-    crs_replace_with_free_ranges(mem_ranges,
+    crs_replace_with_free_ranges(crs_range_set.mem_ranges,
                                  range_lob(pci_hole),
                                  range_upb(pci_hole));
-    for (i = 0; i < mem_ranges->len; i++) {
-        entry = g_ptr_array_index(mem_ranges, i);
+    for (i = 0; i < crs_range_set.mem_ranges->len; i++) {
+        entry = g_ptr_array_index(crs_range_set.mem_ranges, i);
         aml_append(crs,
             aml_dword_memory(AML_POS_DECODE, AML_MIN_FIXED, AML_MAX_FIXED,
                              AML_NON_CACHEABLE, AML_READ_WRITE,
@@ -2064,11 +2117,18 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     }
 
     if (!range_is_empty(pci_hole64)) {
-        aml_append(crs,
-            aml_qword_memory(AML_POS_DECODE, AML_MIN_FIXED, AML_MAX_FIXED,
-                             AML_CACHEABLE, AML_READ_WRITE,
-                             0, range_lob(pci_hole64), range_upb(pci_hole64), 0,
-                             range_upb(pci_hole64) + 1 - range_lob(pci_hole64)));
+        crs_replace_with_free_ranges(crs_range_set.mem_64bit_ranges,
+                                     range_lob(pci_hole64),
+                                     range_upb(pci_hole64));
+        for (i = 0; i < crs_range_set.mem_64bit_ranges->len; i++) {
+            entry = g_ptr_array_index(crs_range_set.mem_64bit_ranges, i);
+            aml_append(crs,
+                       aml_qword_memory(AML_POS_DECODE, AML_MIN_FIXED,
+                                        AML_MAX_FIXED,
+                                        AML_CACHEABLE, AML_READ_WRITE,
+                                        0, entry->base, entry->limit,
+                                        0, entry->limit - entry->base + 1));
+        }
     }
 
     if (misc->tpm_version != TPM_VERSION_UNSPEC) {
@@ -2090,8 +2150,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     aml_append(dev, aml_name_decl("_CRS", crs));
     aml_append(scope, dev);
 
-    g_ptr_array_free(io_ranges, true);
-    g_ptr_array_free(mem_ranges, true);
+    crs_range_set_free(&crs_range_set);
 
     /* reserve PCIHP resources */
     if (pm->pcihp_io_len) {
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index f92d3f829e..dc61dc1c5f 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -140,7 +140,7 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
 {
     int r;
     bool backend_kernel = options->backend_type == VHOST_BACKEND_TYPE_KERNEL;
-    struct vhost_net *net = g_malloc(sizeof *net);
+    struct vhost_net *net = g_new0(struct vhost_net, 1);
     uint64_t features = 0;
 
     if (!options->net_backend) {
@@ -185,7 +185,6 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
             fprintf(stderr, "vhost lacks feature mask %" PRIu64
                    " for backend\n",
                    (uint64_t)(~net->dev.features & net->dev.backend_features));
-            vhost_dev_cleanup(&net->dev);
             goto fail;
         }
     }
@@ -197,7 +196,6 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
             fprintf(stderr, "vhost lacks feature mask %" PRIu64
                     " for backend\n",
                     (uint64_t)(~net->dev.features & features));
-            vhost_dev_cleanup(&net->dev);
             goto fail;
         }
     }
@@ -205,7 +203,9 @@ struct vhost_net *vhost_net_init(VhostNetOptions *options)
     vhost_net_ack_features(net, features);
 
     return net;
+
 fail:
+    vhost_dev_cleanup(&net->dev);
     g_free(net);
     return NULL;
 }
@@ -242,8 +242,7 @@ static int vhost_net_start_one(struct vhost_net *net,
         qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
         file.fd = net->backend;
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
-            const VhostOps *vhost_ops = net->dev.vhost_ops;
-            r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
+            r = vhost_net_set_backend(&net->dev, &file);
             if (r < 0) {
                 r = -errno;
                 goto fail;
@@ -255,8 +254,7 @@ fail:
     file.fd = -1;
     if (net->nc->info->type == NET_CLIENT_DRIVER_TAP) {
         while (file.index-- > 0) {
-            const VhostOps *vhost_ops = net->dev.vhost_ops;
-            int r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
+            int r = vhost_net_set_backend(&net->dev, &file);
             assert(r >= 0);
         }
     }
@@ -277,8 +275,7 @@ static void vhost_net_stop_one(struct vhost_net *net,
 
     if (net->nc->info->type == NET_CLIENT_DRIVER_TAP) {
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
-            const VhostOps *vhost_ops = net->dev.vhost_ops;
-            int r = vhost_ops->vhost_net_set_backend(&net->dev, &file);
+            int r = vhost_net_set_backend(&net->dev, &file);
             assert(r >= 0);
         }
     }
@@ -313,7 +310,7 @@ int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
          * properly.
          */
         if (net->nc->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
-                dev->use_guest_notifier_mask = false;
+            dev->use_guest_notifier_mask = false;
         }
      }
 
@@ -378,19 +375,16 @@ void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
 void vhost_net_cleanup(struct vhost_net *net)
 {
     vhost_dev_cleanup(&net->dev);
-    g_free(net);
 }
 
 int vhost_net_notify_migration_done(struct vhost_net *net, char* mac_addr)
 {
     const VhostOps *vhost_ops = net->dev.vhost_ops;
-    int r = -1;
 
-    if (vhost_ops->vhost_migration_done) {
-        r = vhost_ops->vhost_migration_done(&net->dev, mac_addr);
-    }
+    assert(vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
+    assert(vhost_ops->vhost_migration_done);
 
-    return r;
+    return vhost_ops->vhost_migration_done(&net->dev, mac_addr);
 }
 
 bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
@@ -418,6 +412,7 @@ VHostNetState *get_vhost_net(NetClientState *nc)
         break;
     case NET_CLIENT_DRIVER_VHOST_USER:
         vhost_net = vhost_user_get_vhost_net(nc);
+        assert(vhost_net);
         break;
     default:
         break;
@@ -429,15 +424,10 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 int vhost_set_vring_enable(NetClientState *nc, int enable)
 {
     VHostNetState *net = get_vhost_net(nc);
-    const VhostOps *vhost_ops;
+    const VhostOps *vhost_ops = net->dev.vhost_ops;
 
     nc->vring_enable = enable;
 
-    if (!net) {
-        return 0;
-    }
-
-    vhost_ops = net->dev.vhost_ops;
     if (vhost_ops->vhost_set_vring_enable) {
         return vhost_ops->vhost_set_vring_enable(&net->dev, enable);
     }
diff --git a/hw/pci-bridge/ioh3420.c b/hw/pci-bridge/ioh3420.c
index 0444b596c6..c8b5ac4207 100644
--- a/hw/pci-bridge/ioh3420.c
+++ b/hw/pci-bridge/ioh3420.c
@@ -100,6 +100,7 @@ static int ioh3420_initfn(PCIDevice *d)
     int rc;
     Error *err = NULL;
 
+    pci_config_set_interrupt_pin(d->config, 1);
     pci_bridge_initfn(d, TYPE_PCIE_BUS);
     pcie_port_init_reg(d);
 
diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index ab8612158d..1cc598f7e9 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -11,6 +11,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qapi/error.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bus.h"
 #include "hw/pci/pci_host.h"
@@ -162,30 +163,25 @@ static const TypeInfo pxb_host_info = {
 };
 
 /*
- * Registers the PXB bus as a child of the i440fx root bus.
- *
- * Returns 0 on successs, -1 if i440fx host was not
- * found or the bus number is already in use.
+ * Registers the PXB bus as a child of pci host root bus.
  */
-static int pxb_register_bus(PCIDevice *dev, PCIBus *pxb_bus)
+static void pxb_register_bus(PCIDevice *dev, PCIBus *pxb_bus, Error **errp)
 {
     PCIBus *bus = dev->bus;
     int pxb_bus_num = pci_bus_num(pxb_bus);
 
     if (bus->parent_dev) {
-        error_report("PXB devices can be attached only to root bus.");
-        return -1;
+        error_setg(errp, "PXB devices can be attached only to root bus");
+        return;
     }
 
     QLIST_FOREACH(bus, &bus->child, sibling) {
         if (pci_bus_num(bus) == pxb_bus_num) {
-            error_report("Bus %d is already in use.", pxb_bus_num);
-            return -1;
+            error_setg(errp, "Bus %d is already in use", pxb_bus_num);
+            return;
         }
     }
     QLIST_INSERT_HEAD(&dev->bus->child, pxb_bus, sibling);
-
-    return 0;
 }
 
 static int pxb_map_irq_fn(PCIDevice *pci_dev, int pin)
@@ -215,17 +211,18 @@ static gint pxb_compare(gconstpointer a, gconstpointer b)
            0;
 }
 
-static int pxb_dev_init_common(PCIDevice *dev, bool pcie)
+static void pxb_dev_realize_common(PCIDevice *dev, bool pcie, Error **errp)
 {
     PXBDev *pxb = convert_to_pxb(dev);
     DeviceState *ds, *bds = NULL;
     PCIBus *bus;
     const char *dev_name = NULL;
+    Error *local_err = NULL;
 
     if (pxb->numa_node != NUMA_NODE_UNASSIGNED &&
         pxb->numa_node >= nb_numa_nodes) {
-        error_report("Illegal numa node %d.", pxb->numa_node);
-        return -EINVAL;
+        error_setg(errp, "Illegal numa node %d", pxb->numa_node);
+        return;
     }
 
     if (dev->qdev.id && *dev->qdev.id) {
@@ -250,7 +247,9 @@ static int pxb_dev_init_common(PCIDevice *dev, bool pcie)
 
     PCI_HOST_BRIDGE(ds)->bus = bus;
 
-    if (pxb_register_bus(dev, bus)) {
+    pxb_register_bus(dev, bus, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
         goto err_register_bus;
     }
 
@@ -264,23 +263,22 @@ static int pxb_dev_init_common(PCIDevice *dev, bool pcie)
     pci_config_set_class(dev->config, PCI_CLASS_BRIDGE_HOST);
 
     pxb_dev_list = g_list_insert_sorted(pxb_dev_list, pxb, pxb_compare);
-    return 0;
+    return;
 
 err_register_bus:
     object_unref(OBJECT(bds));
     object_unparent(OBJECT(bus));
     object_unref(OBJECT(ds));
-    return -EINVAL;
 }
 
-static int pxb_dev_initfn(PCIDevice *dev)
+static void pxb_dev_realize(PCIDevice *dev, Error **errp)
 {
     if (pci_bus_is_express(dev->bus)) {
-        error_report("pxb devices cannot reside on a PCIe bus!");
-        return -EINVAL;
+        error_setg(errp, "pxb devices cannot reside on a PCIe bus");
+        return;
     }
 
-    return pxb_dev_init_common(dev, false);
+    pxb_dev_realize_common(dev, false, errp);
 }
 
 static void pxb_dev_exitfn(PCIDevice *pci_dev)
@@ -302,7 +300,7 @@ static void pxb_dev_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
-    k->init = pxb_dev_initfn;
+    k->realize = pxb_dev_realize;
     k->exit = pxb_dev_exitfn;
     k->vendor_id = PCI_VENDOR_ID_REDHAT;
     k->device_id = PCI_DEVICE_ID_REDHAT_PXB;
@@ -310,6 +308,7 @@ static void pxb_dev_class_init(ObjectClass *klass, void *data)
 
     dc->desc = "PCI Expander Bridge";
     dc->props = pxb_dev_properties;
+    dc->hotpluggable = false;
     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
 }
 
@@ -320,14 +319,14 @@ static const TypeInfo pxb_dev_info = {
     .class_init    = pxb_dev_class_init,
 };
 
-static int pxb_pcie_dev_initfn(PCIDevice *dev)
+static void pxb_pcie_dev_realize(PCIDevice *dev, Error **errp)
 {
     if (!pci_bus_is_express(dev->bus)) {
-        error_report("pxb-pcie devices cannot reside on a PCI bus!");
-        return -EINVAL;
+        error_setg(errp, "pxb-pcie devices cannot reside on a PCI bus");
+        return;
     }
 
-    return pxb_dev_init_common(dev, true);
+    pxb_dev_realize_common(dev, true, errp);
 }
 
 static void pxb_pcie_dev_class_init(ObjectClass *klass, void *data)
@@ -335,7 +334,7 @@ static void pxb_pcie_dev_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
-    k->init = pxb_pcie_dev_initfn;
+    k->realize = pxb_pcie_dev_realize;
     k->exit = pxb_dev_exitfn;
     k->vendor_id = PCI_VENDOR_ID_REDHAT;
     k->device_id = PCI_DEVICE_ID_REDHAT_PXB_PCIE;
@@ -343,6 +342,7 @@ static void pxb_pcie_dev_class_init(ObjectClass *klass, void *data)
 
     dc->desc = "PCI Express Expander Bridge";
     dc->props = pxb_dev_properties;
+    dc->hotpluggable = false;
     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
 }
 
diff --git a/hw/pci-host/apb.c b/hw/pci-host/apb.c
index 16587f8373..653e711121 100644
--- a/hw/pci-host/apb.c
+++ b/hw/pci-host/apb.c
@@ -634,7 +634,7 @@ static void pci_apb_set_irq(void *opaque, int irq_num, int level)
     }
 }
 
-static int apb_pci_bridge_initfn(PCIDevice *dev)
+static void apb_pci_bridge_realize(PCIDevice *dev, Error **errp)
 {
     pci_bridge_initfn(dev, TYPE_PCI_BUS);
 
@@ -652,7 +652,6 @@ static int apb_pci_bridge_initfn(PCIDevice *dev)
     pci_set_word(dev->config + PCI_STATUS,
                  PCI_STATUS_FAST_BACK | PCI_STATUS_66MHZ |
                  PCI_STATUS_DEVSEL_MEDIUM);
-    return 0;
 }
 
 PCIBus *pci_apb_init(hwaddr special_base,
@@ -843,7 +842,7 @@ static void pbm_pci_bridge_class_init(ObjectClass *klass, void *data)
     DeviceClass *dc = DEVICE_CLASS(klass);
     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
 
-    k->init = apb_pci_bridge_initfn;
+    k->realize = apb_pci_bridge_realize;
     k->exit = pci_bridge_exitfn;
     k->vendor_id = PCI_VENDOR_ID_SUN;
     k->device_id = PCI_DEVICE_ID_SUN_SIMBA;
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 728c6d4b3b..24fae1689d 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -62,6 +62,8 @@ static Property pci_props[] = {
                     QEMU_PCI_CAP_MULTIFUNCTION_BITNR, false),
     DEFINE_PROP_BIT("command_serr_enable", PCIDevice, cap_present,
                     QEMU_PCI_CAP_SERR_BITNR, true),
+    DEFINE_PROP_BIT("x-pcie-lnksta-dllla", PCIDevice, cap_present,
+                    QEMU_PCIE_LNKSTA_DLLLA_BITNR, true),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index 9599fdef57..99cfb4561b 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -45,8 +45,11 @@
  */
 
 static void
-pcie_cap_v1_fill(uint8_t *exp_cap, uint8_t port, uint8_t type, uint8_t version)
+pcie_cap_v1_fill(PCIDevice *dev, uint8_t port, uint8_t type, uint8_t version)
 {
+    uint8_t *exp_cap = dev->config + dev->exp.exp_cap;
+    uint8_t *cmask = dev->cmask + dev->exp.exp_cap;
+
     /* capability register
     interrupt message number defaults to 0 */
     pci_set_word(exp_cap + PCI_EXP_FLAGS,
@@ -69,7 +72,18 @@ pcie_cap_v1_fill(uint8_t *exp_cap, uint8_t port, uint8_t type, uint8_t version)
                  PCI_EXP_LNK_LS_25);
 
     pci_set_word(exp_cap + PCI_EXP_LNKSTA,
-                 PCI_EXP_LNK_MLW_1 | PCI_EXP_LNK_LS_25 |PCI_EXP_LNKSTA_DLLLA);
+                 PCI_EXP_LNK_MLW_1 | PCI_EXP_LNK_LS_25);
+
+    if (dev->cap_present & QEMU_PCIE_LNKSTA_DLLLA) {
+        pci_word_test_and_set_mask(exp_cap + PCI_EXP_LNKSTA,
+                                   PCI_EXP_LNKSTA_DLLLA);
+    }
+
+    /* We changed link status bits over time, and changing them across
+     * migrations is generally fine as hardware changes them too.
+     * Let's not bother checking.
+     */
+    pci_set_word(cmask + PCI_EXP_LNKSTA, 0);
 }
 
 int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port)
@@ -88,7 +102,7 @@ int pcie_cap_init(PCIDevice *dev, uint8_t offset, uint8_t type, uint8_t port)
     exp_cap = dev->config + pos;
 
     /* Filling values common with v1 */
-    pcie_cap_v1_fill(exp_cap, port, type, PCI_EXP_FLAGS_VER2);
+    pcie_cap_v1_fill(dev, port, type, PCI_EXP_FLAGS_VER2);
 
     /* Filling v2 specific values */
     pci_set_long(exp_cap + PCI_EXP_DEVCAP2,
@@ -103,7 +117,6 @@ int pcie_cap_v1_init(PCIDevice *dev, uint8_t offset, uint8_t type,
 {
     /* PCIe cap v1 init */
     int pos;
-    uint8_t *exp_cap;
 
     assert(pci_is_express(dev));
 
@@ -112,9 +125,8 @@ int pcie_cap_v1_init(PCIDevice *dev, uint8_t offset, uint8_t type,
         return pos;
     }
     dev->exp.exp_cap = pos;
-    exp_cap = dev->config + pos;
 
-    pcie_cap_v1_fill(exp_cap, port, type, PCI_EXP_FLAGS_VER1);
+    pcie_cap_v1_fill(dev, port, type, PCI_EXP_FLAGS_VER1);
 
     return pos;
 }
diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c
index 1ae32fb7d3..bebe5130fe 100644
--- a/hw/scsi/mptsas.c
+++ b/hw/scsi/mptsas.c
@@ -1370,7 +1370,7 @@ static const VMStateDescription vmstate_mptsas = {
     .post_load = mptsas_post_load,
     .fields      = (VMStateField[]) {
         VMSTATE_PCI_DEVICE(dev, MPTSASState),
-
+        VMSTATE_UNUSED(sizeof(bool)), /* Was msi_in_use */
         VMSTATE_UINT32(state, MPTSASState),
         VMSTATE_UINT8(who_init, MPTSASState),
         VMSTATE_UINT8(doorbell_state, MPTSASState),
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 495e09fd4e..1995fd20bd 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -176,7 +176,7 @@ static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
                             int *fds, int fd_num)
 {
     CharDriverState *chr = dev->opaque;
-    int size = VHOST_USER_HDR_SIZE + msg->size;
+    int ret, size = VHOST_USER_HDR_SIZE + msg->size;
 
     /*
      * For non-vring specific requests, like VHOST_USER_SET_MEM_TABLE,
@@ -187,12 +187,19 @@ static int vhost_user_write(struct vhost_dev *dev, VhostUserMsg *msg,
         return 0;
     }
 
-    if (fd_num) {
-        qemu_chr_fe_set_msgfds(chr, fds, fd_num);
+    if (qemu_chr_fe_set_msgfds(chr, fds, fd_num) < 0) {
+        error_report("Failed to set msg fds.");
+        return -1;
+    }
+
+    ret = qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size);
+    if (ret != size) {
+        error_report("Failed to write msg."
+                     " Wrote %d instead of %d.", ret, size);
+        return -1;
     }
 
-    return qemu_chr_fe_write_all(chr, (const uint8_t *) msg, size) == size ?
-            0 : -1;
+    return 0;
 }
 
 static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
@@ -214,12 +221,14 @@ static int vhost_user_set_log_base(struct vhost_dev *dev, uint64_t base,
         fds[fd_num++] = log->fd;
     }
 
-    vhost_user_write(dev, &msg, fds, fd_num);
+    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
+        return -1;
+    }
 
     if (shmfd) {
         msg.size = 0;
         if (vhost_user_read(dev, &msg) < 0) {
-            return 0;
+            return -1;
         }
 
         if (msg.request != VHOST_USER_SET_LOG_BASE) {
@@ -275,7 +284,9 @@ static int vhost_user_set_mem_table(struct vhost_dev *dev,
     msg.size += sizeof(msg.payload.memory.padding);
     msg.size += fd_num * sizeof(VhostUserMemoryRegion);
 
-    vhost_user_write(dev, &msg, fds, fd_num);
+    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -290,7 +301,9 @@ static int vhost_user_set_vring_addr(struct vhost_dev *dev,
         .size = sizeof(msg.payload.addr),
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -313,7 +326,9 @@ static int vhost_set_vring(struct vhost_dev *dev,
         .size = sizeof(msg.payload.state),
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -360,10 +375,12 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev,
         .size = sizeof(msg.payload.state),
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     if (vhost_user_read(dev, &msg) < 0) {
-        return 0;
+        return -1;
     }
 
     if (msg.request != VHOST_USER_GET_VRING_BASE) {
@@ -401,7 +418,9 @@ static int vhost_set_vring_file(struct vhost_dev *dev,
         msg.payload.u64 |= VHOST_USER_VRING_NOFD_MASK;
     }
 
-    vhost_user_write(dev, &msg, fds, fd_num);
+    if (vhost_user_write(dev, &msg, fds, fd_num) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -427,7 +446,9 @@ static int vhost_user_set_u64(struct vhost_dev *dev, int request, uint64_t u64)
         .size = sizeof(msg.payload.u64),
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -455,10 +476,12 @@ static int vhost_user_get_u64(struct vhost_dev *dev, int request, uint64_t *u64)
         return 0;
     }
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     if (vhost_user_read(dev, &msg) < 0) {
-        return 0;
+        return -1;
     }
 
     if (msg.request != request) {
@@ -489,7 +512,9 @@ static int vhost_user_set_owner(struct vhost_dev *dev)
         .flags = VHOST_USER_VERSION,
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -501,7 +526,9 @@ static int vhost_user_reset_device(struct vhost_dev *dev)
         .flags = VHOST_USER_VERSION,
     };
 
-    vhost_user_write(dev, &msg, NULL, 0);
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
 
     return 0;
 }
@@ -588,7 +615,6 @@ static bool vhost_user_requires_shm_log(struct vhost_dev *dev)
 static int vhost_user_migration_done(struct vhost_dev *dev, char* mac_addr)
 {
     VhostUserMsg msg = { 0 };
-    int err;
 
     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
 
@@ -605,8 +631,7 @@ static int vhost_user_migration_done(struct vhost_dev *dev, char* mac_addr)
         memcpy((char *)&msg.payload.u64, mac_addr, 6);
         msg.size = sizeof(msg.payload.u64);
 
-        err = vhost_user_write(dev, &msg, NULL, 0);
-        return err;
+        return vhost_user_write(dev, &msg, NULL, 0);
     }
     return -1;
 }
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index ec3abda9d5..3d0c807d0e 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -27,6 +27,18 @@
 #include "hw/virtio/virtio-access.h"
 #include "migration/migration.h"
 
+/* enabled until disconnected backend stabilizes */
+#define _VHOST_DEBUG 1
+
+#ifdef _VHOST_DEBUG
+#define VHOST_OPS_DEBUG(fmt, ...) \
+    do { error_report(fmt ": %s (%d)", ## __VA_ARGS__, \
+                      strerror(errno), errno); } while (0)
+#else
+#define VHOST_OPS_DEBUG(fmt, ...) \
+    do { } while (0)
+#endif
+
 static struct vhost_log *vhost_log;
 static struct vhost_log *vhost_log_shm;
 
@@ -362,6 +374,8 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync)
     if (!log) {
         return;
     }
+    dev->log = NULL;
+    dev->log_size = 0;
 
     --log->refcnt;
     if (log->refcnt == 0) {
@@ -398,7 +412,10 @@ static inline void vhost_dev_log_resize(struct vhost_dev *dev, uint64_t size)
     /* inform backend of log switching, this must be done before
        releasing the current log, to ensure no logging is lost */
     r = dev->vhost_ops->vhost_set_log_base(dev, log_base, log);
-    assert(r >= 0);
+    if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_log_base failed");
+    }
+
     vhost_log_put(dev, true);
     dev->log = log;
     dev->log_size = size;
@@ -422,11 +439,11 @@ static int vhost_verify_ring_mappings(struct vhost_dev *dev,
         l = vq->ring_size;
         p = cpu_physical_memory_map(vq->ring_phys, &l, 1);
         if (!p || l != vq->ring_size) {
-            fprintf(stderr, "Unable to map ring buffer for ring %d\n", i);
+            error_report("Unable to map ring buffer for ring %d", i);
             r = -ENOMEM;
         }
         if (p != vq->ring) {
-            fprintf(stderr, "Ring buffer relocated for ring %d\n", i);
+            error_report("Ring buffer relocated for ring %d", i);
             r = -EBUSY;
         }
         cpu_physical_memory_unmap(p, l, 0, 0);
@@ -565,7 +582,9 @@ static void vhost_commit(MemoryListener *listener)
 
     if (!dev->log_enabled) {
         r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
-        assert(r >= 0);
+        if (r < 0) {
+            VHOST_OPS_DEBUG("vhost_set_mem_table failed");
+        }
         dev->memory_changed = false;
         return;
     }
@@ -578,7 +597,9 @@ static void vhost_commit(MemoryListener *listener)
         vhost_dev_log_resize(dev, log_size + VHOST_LOG_BUFFER);
     }
     r = dev->vhost_ops->vhost_set_mem_table(dev, dev->mem);
-    assert(r >= 0);
+    if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_mem_table failed");
+    }
     /* To log less, can only decrease log size after table update. */
     if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
         vhost_dev_log_resize(dev, log_size);
@@ -647,6 +668,7 @@ static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
     };
     int r = dev->vhost_ops->vhost_set_vring_addr(dev, &addr);
     if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_vring_addr failed");
         return -errno;
     }
     return 0;
@@ -660,12 +682,15 @@ static int vhost_dev_set_features(struct vhost_dev *dev, bool enable_log)
         features |= 0x1ULL << VHOST_F_LOG_ALL;
     }
     r = dev->vhost_ops->vhost_set_features(dev, features);
+    if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_features failed");
+    }
     return r < 0 ? -errno : 0;
 }
 
 static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
 {
-    int r, t, i, idx;
+    int r, i, idx;
     r = vhost_dev_set_features(dev, enable_log);
     if (r < 0) {
         goto err_features;
@@ -682,12 +707,10 @@ static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
 err_vq:
     for (; i >= 0; --i) {
         idx = dev->vhost_ops->vhost_get_vq_index(dev, dev->vq_index + i);
-        t = vhost_virtqueue_set_addr(dev, dev->vqs + i, idx,
-                                     dev->log_enabled);
-        assert(t >= 0);
+        vhost_virtqueue_set_addr(dev, dev->vqs + i, idx,
+                                 dev->log_enabled);
     }
-    t = vhost_dev_set_features(dev, dev->log_enabled);
-    assert(t >= 0);
+    vhost_dev_set_features(dev, dev->log_enabled);
 err_features:
     return r;
 }
@@ -710,8 +733,6 @@ static int vhost_migration_log(MemoryListener *listener, int enable)
             return r;
         }
         vhost_log_put(dev, false);
-        dev->log = NULL;
-        dev->log_size = 0;
     } else {
         vhost_dev_log_resize(dev, vhost_get_log_size(dev));
         r = vhost_dev_set_log(dev, true);
@@ -787,6 +808,7 @@ static int vhost_virtqueue_set_vring_endian_legacy(struct vhost_dev *dev,
         return 0;
     }
 
+    VHOST_OPS_DEBUG("vhost_set_vring_endian failed");
     if (errno == ENOTTY) {
         error_report("vhost does not support cross-endian");
         return -ENOSYS;
@@ -815,12 +837,14 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
     vq->num = state.num = virtio_queue_get_num(vdev, idx);
     r = dev->vhost_ops->vhost_set_vring_num(dev, &state);
     if (r) {
+        VHOST_OPS_DEBUG("vhost_set_vring_num failed");
         return -errno;
     }
 
     state.num = virtio_queue_get_last_avail_idx(vdev, idx);
     r = dev->vhost_ops->vhost_set_vring_base(dev, &state);
     if (r) {
+        VHOST_OPS_DEBUG("vhost_set_vring_base failed");
         return -errno;
     }
 
@@ -872,6 +896,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
     file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));
     r = dev->vhost_ops->vhost_set_vring_kick(dev, &file);
     if (r) {
+        VHOST_OPS_DEBUG("vhost_set_vring_kick failed");
         r = -errno;
         goto fail_kick;
     }
@@ -919,25 +944,21 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
 
     r = dev->vhost_ops->vhost_get_vring_base(dev, &state);
     if (r < 0) {
-        fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);
-        fflush(stderr);
+        VHOST_OPS_DEBUG("vhost VQ %d ring restore failed: %d", idx, r);
+    } else {
+        virtio_queue_set_last_avail_idx(vdev, idx, state.num);
     }
-    virtio_queue_set_last_avail_idx(vdev, idx, state.num);
     virtio_queue_invalidate_signalled_used(vdev, idx);
 
     /* In the cross-endian case, we need to reset the vring endianness to
      * native as legacy devices expect so by default.
      */
     if (vhost_needs_vring_endian(vdev)) {
-        r = vhost_virtqueue_set_vring_endian_legacy(dev,
-                                                    !virtio_is_big_endian(vdev),
-                                                    vhost_vq_index);
-        if (r < 0) {
-            error_report("failed to reset vring endianness");
-        }
+        vhost_virtqueue_set_vring_endian_legacy(dev,
+                                                !virtio_is_big_endian(vdev),
+                                                vhost_vq_index);
     }
 
-    assert (r >= 0);
     cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
                               0, virtio_queue_get_ring_size(vdev, idx));
     cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
@@ -976,6 +997,7 @@ static int vhost_virtqueue_set_busyloop_timeout(struct vhost_dev *dev,
 
     r = dev->vhost_ops->vhost_set_vring_busyloop_timeout(dev, &state);
     if (r) {
+        VHOST_OPS_DEBUG("vhost_set_vring_busyloop_timeout failed");
         return r;
     }
 
@@ -997,6 +1019,7 @@ static int vhost_virtqueue_init(struct vhost_dev *dev,
     file.fd = event_notifier_get_fd(&vq->masked_notifier);
     r = dev->vhost_ops->vhost_set_vring_call(dev, &file);
     if (r) {
+        VHOST_OPS_DEBUG("vhost_set_vring_call failed");
         r = -errno;
         goto fail_call;
     }
@@ -1015,42 +1038,41 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                    VhostBackendType backend_type, uint32_t busyloop_timeout)
 {
     uint64_t features;
-    int i, r;
+    int i, r, n_initialized_vqs = 0;
 
     hdev->migration_blocker = NULL;
 
-    if (vhost_set_backend_type(hdev, backend_type) < 0) {
-        close((uintptr_t)opaque);
-        return -1;
-    }
+    r = vhost_set_backend_type(hdev, backend_type);
+    assert(r >= 0);
 
-    if (hdev->vhost_ops->vhost_backend_init(hdev, opaque) < 0) {
-        close((uintptr_t)opaque);
-        return -errno;
+    r = hdev->vhost_ops->vhost_backend_init(hdev, opaque);
+    if (r < 0) {
+        goto fail;
     }
 
     if (used_memslots > hdev->vhost_ops->vhost_backend_memslots_limit(hdev)) {
-        fprintf(stderr, "vhost backend memory slots limit is less"
-                " than current number of present memory slots\n");
-        close((uintptr_t)opaque);
-        return -1;
+        error_report("vhost backend memory slots limit is less"
+                " than current number of present memory slots");
+        r = -1;
+        goto fail;
     }
-    QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
 
     r = hdev->vhost_ops->vhost_set_owner(hdev);
     if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_owner failed");
         goto fail;
     }
 
     r = hdev->vhost_ops->vhost_get_features(hdev, &features);
     if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_get_features failed");
         goto fail;
     }
 
-    for (i = 0; i < hdev->nvqs; ++i) {
+    for (i = 0; i < hdev->nvqs; ++i, ++n_initialized_vqs) {
         r = vhost_virtqueue_init(hdev, hdev->vqs + i, hdev->vq_index + i);
         if (r < 0) {
-            goto fail_vq;
+            goto fail;
         }
     }
 
@@ -1105,38 +1127,43 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     hdev->started = false;
     hdev->memory_changed = false;
     memory_listener_register(&hdev->memory_listener, &address_space_memory);
+    QLIST_INSERT_HEAD(&vhost_devices, hdev, entry);
     return 0;
+
 fail_busyloop:
     while (--i >= 0) {
         vhost_virtqueue_set_busyloop_timeout(hdev, hdev->vq_index + i, 0);
     }
-    i = hdev->nvqs;
-fail_vq:
-    while (--i >= 0) {
-        vhost_virtqueue_cleanup(hdev->vqs + i);
-    }
 fail:
-    r = -errno;
-    hdev->vhost_ops->vhost_backend_cleanup(hdev);
-    QLIST_REMOVE(hdev, entry);
+    hdev->nvqs = n_initialized_vqs;
+    vhost_dev_cleanup(hdev);
     return r;
 }
 
 void vhost_dev_cleanup(struct vhost_dev *hdev)
 {
     int i;
+
     for (i = 0; i < hdev->nvqs; ++i) {
         vhost_virtqueue_cleanup(hdev->vqs + i);
     }
-    memory_listener_unregister(&hdev->memory_listener);
+    if (hdev->mem) {
+        /* those are only safe after successful init */
+        memory_listener_unregister(&hdev->memory_listener);
+        QLIST_REMOVE(hdev, entry);
+    }
     if (hdev->migration_blocker) {
         migrate_del_blocker(hdev->migration_blocker);
         error_free(hdev->migration_blocker);
     }
     g_free(hdev->mem);
     g_free(hdev->mem_sections);
-    hdev->vhost_ops->vhost_backend_cleanup(hdev);
-    QLIST_REMOVE(hdev, entry);
+    if (hdev->vhost_ops) {
+        hdev->vhost_ops->vhost_backend_cleanup(hdev);
+    }
+    assert(!hdev->log);
+
+    memset(hdev, 0, sizeof(struct vhost_dev));
 }
 
 /* Stop processing guest IO notifications in qemu.
@@ -1148,8 +1175,9 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r, e;
+
     if (!k->ioeventfd_started) {
-        fprintf(stderr, "binding does not support host notifiers\n");
+        error_report("binding does not support host notifiers");
         r = -ENOSYS;
         goto fail;
     }
@@ -1158,7 +1186,7 @@ int vhost_dev_enable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
         r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          true);
         if (r < 0) {
-            fprintf(stderr, "vhost VQ %d notifier binding failed: %d\n", i, -r);
+            error_report("vhost VQ %d notifier binding failed: %d", i, -r);
             goto fail_vq;
         }
     }
@@ -1169,8 +1197,7 @@ fail_vq:
         e = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          false);
         if (e < 0) {
-            fprintf(stderr, "vhost VQ %d notifier cleanup error: %d\n", i, -r);
-            fflush(stderr);
+            error_report("vhost VQ %d notifier cleanup error: %d", i, -r);
         }
         assert (e >= 0);
     }
@@ -1192,8 +1219,7 @@ void vhost_dev_disable_notifiers(struct vhost_dev *hdev, VirtIODevice *vdev)
         r = virtio_bus_set_host_notifier(VIRTIO_BUS(qbus), hdev->vq_index + i,
                                          false);
         if (r < 0) {
-            fprintf(stderr, "vhost VQ %d notifier cleanup failed: %d\n", i, -r);
-            fflush(stderr);
+            error_report("vhost VQ %d notifier cleanup failed: %d", i, -r);
         }
         assert (r >= 0);
     }
@@ -1217,6 +1243,9 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
     int r, index = n - hdev->vq_index;
     struct vhost_vring_file file;
 
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
     if (mask) {
         assert(vdev->use_guest_notifier_mask);
         file.fd = event_notifier_get_fd(&hdev->vqs[index].masked_notifier);
@@ -1226,7 +1255,9 @@ void vhost_virtqueue_mask(struct vhost_dev *hdev, VirtIODevice *vdev, int n,
 
     file.index = hdev->vhost_ops->vhost_get_vq_index(hdev, n);
     r = hdev->vhost_ops->vhost_set_vring_call(hdev, &file);
-    assert(r >= 0);
+    if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_vring_call failed");
+    }
 }
 
 uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
@@ -1261,6 +1292,9 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
 {
     int i, r;
 
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
     hdev->started = true;
 
     r = vhost_dev_set_features(hdev, hdev->log_enabled);
@@ -1269,6 +1303,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
     }
     r = hdev->vhost_ops->vhost_set_mem_table(hdev, hdev->mem);
     if (r < 0) {
+        VHOST_OPS_DEBUG("vhost_set_mem_table failed");
         r = -errno;
         goto fail_mem;
     }
@@ -1293,6 +1328,7 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
                                                 hdev->log_size ? log_base : 0,
                                                 hdev->log);
         if (r < 0) {
+            VHOST_OPS_DEBUG("vhost_set_log_base failed");
             r = -errno;
             goto fail_log;
         }
@@ -1321,6 +1357,9 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
 {
     int i;
 
+    /* should only be called after backend is connected */
+    assert(hdev->vhost_ops);
+
     for (i = 0; i < hdev->nvqs; ++i) {
         vhost_virtqueue_stop(hdev,
                              vdev,
@@ -1330,7 +1369,14 @@ void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
 
     vhost_log_put(hdev, true);
     hdev->started = false;
-    hdev->log = NULL;
-    hdev->log_size = 0;
 }
 
+int vhost_net_set_backend(struct vhost_dev *hdev,
+                          struct vhost_vring_file *file)
+{
+    if (hdev->vhost_ops->vhost_net_set_backend) {
+        return hdev->vhost_ops->vhost_net_set_backend(hdev, file);
+    }
+
+    return -1;
+}
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index f0677b73d8..755f9218b7 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -161,7 +161,7 @@ static bool virtio_pci_modern_state_needed(void *opaque)
 {
     VirtIOPCIProxy *proxy = opaque;
 
-    return !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+    return virtio_pci_modern(proxy);
 }
 
 static const VMStateDescription vmstate_virtio_pci_modern_state = {
@@ -300,8 +300,8 @@ static int virtio_pci_ioeventfd_assign(DeviceState *d, EventNotifier *notifier,
     VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
     VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
     VirtQueue *vq = virtio_get_queue(vdev, n);
-    bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
-    bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+    bool legacy = virtio_pci_legacy(proxy);
+    bool modern = virtio_pci_modern(proxy);
     bool fast_mmio = kvm_ioeventfd_any_length_enabled();
     bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
     MemoryRegion *modern_mr = &proxy->notify.mr;
@@ -1574,8 +1574,8 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
 {
     VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
     VirtioBusState *bus = &proxy->bus;
-    bool legacy = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_LEGACY);
-    bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+    bool legacy = virtio_pci_legacy(proxy);
+    bool modern = virtio_pci_modern(proxy);
     bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
     uint8_t *config;
     uint32_t size;
@@ -1694,7 +1694,7 @@ static void virtio_pci_device_plugged(DeviceState *d, Error **errp)
 static void virtio_pci_device_unplugged(DeviceState *d)
 {
     VirtIOPCIProxy *proxy = VIRTIO_PCI(d);
-    bool modern = !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN);
+    bool modern = virtio_pci_modern(proxy);
     bool modern_pio = proxy->flags & VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY;
 
     virtio_pci_stop_ioeventfd(proxy);
@@ -1714,6 +1714,8 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
 {
     VirtIOPCIProxy *proxy = VIRTIO_PCI(pci_dev);
     VirtioPCIClass *k = VIRTIO_PCI_GET_CLASS(pci_dev);
+    bool pcie_port = pci_bus_is_express(pci_dev->bus) &&
+                     !pci_bus_is_root(pci_dev->bus);
 
     /*
      * virtio pci bar layout used by default.
@@ -1764,8 +1766,11 @@ static void virtio_pci_realize(PCIDevice *pci_dev, Error **errp)
 
     address_space_init(&proxy->modern_as, &proxy->modern_cfg, "virtio-pci-cfg-as");
 
-    if (pci_is_express(pci_dev) && pci_bus_is_express(pci_dev->bus) &&
-        !pci_bus_is_root(pci_dev->bus)) {
+    if (proxy->disable_legacy == ON_OFF_AUTO_AUTO) {
+        proxy->disable_legacy = pcie_port ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
+    }
+
+    if (pcie_port && pci_is_express(pci_dev)) {
         int pos;
 
         pos = pcie_endpoint_cap_init(pci_dev, 0);
@@ -1819,10 +1824,9 @@ static void virtio_pci_reset(DeviceState *qdev)
 static Property virtio_pci_properties[] = {
     DEFINE_PROP_BIT("virtio-pci-bus-master-bug-migration", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT, false),
-    DEFINE_PROP_BIT("disable-legacy", VirtIOPCIProxy, flags,
-                    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT, false),
-    DEFINE_PROP_BIT("disable-modern", VirtIOPCIProxy, flags,
-                    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT, true),
+    DEFINE_PROP_ON_OFF_AUTO("disable-legacy", VirtIOPCIProxy, disable_legacy,
+                            ON_OFF_AUTO_AUTO),
+    DEFINE_PROP_BOOL("disable-modern", VirtIOPCIProxy, disable_modern, false),
     DEFINE_PROP_BIT("migrate-extra", VirtIOPCIProxy, flags,
                     VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT, true),
     DEFINE_PROP_BIT("modern-pio-notify", VirtIOPCIProxy, flags,
@@ -1839,7 +1843,7 @@ static void virtio_pci_dc_realize(DeviceState *qdev, Error **errp)
     PCIDevice *pci_dev = &proxy->pci_dev;
 
     if (!(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_PCIE) &&
-        !(proxy->flags & VIRTIO_PCI_FLAG_DISABLE_MODERN)) {
+        virtio_pci_modern(proxy)) {
         pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
     }
 
@@ -2301,9 +2305,7 @@ static void virtio_input_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
     DeviceState *vdev = DEVICE(&vinput->vdev);
 
     qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
-    /* force virtio-1.0 */
-    vpci_dev->flags &= ~VIRTIO_PCI_FLAG_DISABLE_MODERN;
-    vpci_dev->flags |= VIRTIO_PCI_FLAG_DISABLE_LEGACY;
+    virtio_pci_force_virtio_1(vpci_dev);
     object_property_set_bool(OBJECT(vdev), true, "realized", errp);
 }
 
diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h
index e4548c2f97..25fbf8a375 100644
--- a/hw/virtio/virtio-pci.h
+++ b/hw/virtio/virtio-pci.h
@@ -61,8 +61,6 @@ typedef struct VirtioBusClass VirtioPCIBusClass;
 enum {
     VIRTIO_PCI_FLAG_BUS_MASTER_BUG_MIGRATION_BIT,
     VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT,
-    VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT,
-    VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT,
     VIRTIO_PCI_FLAG_MIGRATE_EXTRA_BIT,
     VIRTIO_PCI_FLAG_MODERN_PIO_NOTIFY_BIT,
     VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT,
@@ -77,8 +75,6 @@ enum {
 #define VIRTIO_PCI_FLAG_USE_IOEVENTFD   (1 << VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT)
 
 /* virtio version flags */
-#define VIRTIO_PCI_FLAG_DISABLE_LEGACY (1 << VIRTIO_PCI_FLAG_DISABLE_LEGACY_BIT)
-#define VIRTIO_PCI_FLAG_DISABLE_MODERN (1 << VIRTIO_PCI_FLAG_DISABLE_MODERN_BIT)
 #define VIRTIO_PCI_FLAG_DISABLE_PCIE (1 << VIRTIO_PCI_FLAG_DISABLE_PCIE_BIT)
 
 /* migrate extra state */
@@ -144,6 +140,8 @@ struct VirtIOPCIProxy {
     uint32_t modern_mem_bar;
     int config_cap;
     uint32_t flags;
+    bool disable_modern;
+    OnOffAuto disable_legacy;
     uint32_t class_code;
     uint32_t nvectors;
     uint32_t dfselect;
@@ -158,6 +156,21 @@ struct VirtIOPCIProxy {
     VirtioBusState bus;
 };
 
+static inline bool virtio_pci_modern(VirtIOPCIProxy *proxy)
+{
+    return !proxy->disable_modern;
+}
+
+static inline bool virtio_pci_legacy(VirtIOPCIProxy *proxy)
+{
+    return proxy->disable_legacy == ON_OFF_AUTO_OFF;
+}
+
+static inline void virtio_pci_force_virtio_1(VirtIOPCIProxy *proxy)
+{
+    proxy->disable_modern = false;
+    proxy->disable_legacy = ON_OFF_AUTO_ON;
+}
 
 /*
  * virtio-scsi-pci: This extends VirtioPCIProxy.
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 28cf504d6a..15ee3a71fa 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -458,6 +458,11 @@ static void virtqueue_map_desc(unsigned int *p_num_sg, hwaddr *addr, struct iove
     unsigned num_sg = *p_num_sg;
     assert(num_sg <= max_num_sg);
 
+    if (!sz) {
+        error_report("virtio: zero sized buffers are not allowed");
+        exit(1);
+    }
+
     while (sz) {
         hwaddr len = sz;