Merge remote-tracking branch 'remotes/mst/tags/for_upstream3' into staging

pc,pci,virtio: lots of new features

Lots of last minute stuff.

vhost-user-i2c.
vhost-vsock SOCK_SEQPACKET support.
IOMMU bypass.
ACPI based pci hotplug.

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

# gpg: Signature made Fri 16 Jul 2021 16:11:27 BST
# gpg:                using RSA key 5D09FD0871C8F85B94CA8A0D281F0DB8D28D5469
# gpg:                issuer "mst@redhat.com"
# gpg: Good signature from "Michael S. Tsirkin <mst@kernel.org>" [full]
# gpg:                 aka "Michael S. Tsirkin <mst@redhat.com>" [full]
# 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_upstream3:
  vhost-vsock: SOCK_SEQPACKET feature bit support
  docs: Add documentation for iommu bypass
  hw/i386/acpi-build: Add IVRS support to bypass iommu
  hw/i386/acpi-build: Add DMAR support to bypass iommu
  hw/arm/virt-acpi-build: Add IORT support to bypass SMMUv3
  hw/pci: Add pci_bus_range() to get PCI bus number range
  hw/i386: Add a default_bus_bypass_iommu pc machine option
  hw/arm/virt: Add default_bus_bypass_iommu machine option
  hw/pxb: Add a bypass iommu property
  hw/pci/pci_host: Allow PCI host to bypass iommu
  docs: Add '-device intel-iommu' entry
  hw/virtio: add vhost-user-i2c-pci boilerplate
  hw/virtio: add boilerplate for vhost-user-i2c device
  bios-tables-test: Update golden binaries
  hw/acpi/ich9: Set ACPI PCI hot-plug as default on Q35
  bios-tables-test: Allow changes in DSDT ACPI tables
  hw/pci/pcie: Do not set HPC flag if acpihp is used
  hw/acpi/ich9: Enable ACPI PCI hot-plug
  hw/i386/acpi-build: Add ACPI PCI hot-plug methods to Q35

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

22 files changed, 783 insertions, 40 deletions

diff --git a/hw/acpi/acpi-x86-stub.c b/hw/acpi/acpi-x86-stub.c
index f88d6a0..e9e46c5 100644
--- a/hw/acpi/acpi-x86-stub.c
+++ b/hw/acpi/acpi-x86-stub.c
@@ -1,7 +1,13 @@
 #include "qemu/osdep.h"
 #include "hw/i386/pc.h"
+#include "hw/i386/acpi-build.h"
 
 void pc_madt_cpu_entry(AcpiDeviceIf *adev, int uid,
                        const CPUArchIdList *apic_ids, GArray *entry)
 {
 }
+
+Object *acpi_get_i386_pci_host(void)
+{
+       return NULL;
+}
diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index 4daa79e..778e27b 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -217,6 +217,26 @@ static const VMStateDescription vmstate_cpuhp_state = {
     }
 };
 
+static bool vmstate_test_use_pcihp(void *opaque)
+{
+    ICH9LPCPMRegs *s = opaque;
+
+    return s->use_acpi_hotplug_bridge;
+}
+
+static const VMStateDescription vmstate_pcihp_state = {
+    .name = "ich9_pm/pcihp",
+    .version_id = 1,
+    .minimum_version_id = 1,
+    .needed = vmstate_test_use_pcihp,
+    .fields      = (VMStateField[]) {
+        VMSTATE_PCI_HOTPLUG(acpi_pci_hotplug,
+                            ICH9LPCPMRegs,
+                            NULL, NULL),
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 const VMStateDescription vmstate_ich9_pm = {
     .name = "ich9_pm",
     .version_id = 1,
@@ -238,6 +258,7 @@ const VMStateDescription vmstate_ich9_pm = {
         &vmstate_memhp_state,
         &vmstate_tco_io_state,
         &vmstate_cpuhp_state,
+        &vmstate_pcihp_state,
         NULL
     }
 };
@@ -259,6 +280,10 @@ static void pm_reset(void *opaque)
     }
     pm->smi_en_wmask = ~0;
 
+    if (pm->use_acpi_hotplug_bridge) {
+        acpi_pcihp_reset(&pm->acpi_pci_hotplug, true);
+    }
+
     acpi_update_sci(&pm->acpi_regs, pm->irq);
 }
 
@@ -297,6 +322,18 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm,
     pm->enable_tco = true;
     acpi_pm_tco_init(&pm->tco_regs, &pm->io);
 
+    if (pm->use_acpi_hotplug_bridge) {
+        acpi_pcihp_init(OBJECT(lpc_pci),
+                        &pm->acpi_pci_hotplug,
+                        pci_get_bus(lpc_pci),
+                        pci_address_space_io(lpc_pci),
+                        true,
+                        ACPI_PCIHP_ADDR_ICH9);
+
+        qbus_set_hotplug_handler(BUS(pci_get_bus(lpc_pci)),
+                                 OBJECT(lpc_pci));
+    }
+
     pm->irq = sci_irq;
     qemu_register_reset(pm_reset, pm);
     pm->powerdown_notifier.notify = pm_powerdown_req;
@@ -368,6 +405,20 @@ static void ich9_pm_set_enable_tco(Object *obj, bool value, Error **errp)
     s->pm.enable_tco = value;
 }
 
+static bool ich9_pm_get_acpi_pci_hotplug(Object *obj, Error **errp)
+{
+    ICH9LPCState *s = ICH9_LPC_DEVICE(obj);
+
+    return s->pm.use_acpi_hotplug_bridge;
+}
+
+static void ich9_pm_set_acpi_pci_hotplug(Object *obj, bool value, Error **errp)
+{
+    ICH9LPCState *s = ICH9_LPC_DEVICE(obj);
+
+    s->pm.use_acpi_hotplug_bridge = value;
+}
+
 void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm)
 {
     static const uint32_t gpe0_len = ICH9_PMIO_GPE0_LEN;
@@ -376,6 +427,7 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm)
     pm->disable_s3 = 0;
     pm->disable_s4 = 0;
     pm->s4_val = 2;
+    pm->use_acpi_hotplug_bridge = true;
 
     object_property_add_uint32_ptr(obj, ACPI_PM_PROP_PM_IO_BASE,
                                    &pm->pm_io_base, OBJ_PROP_FLAG_READ);
@@ -399,6 +451,9 @@ void ich9_pm_add_properties(Object *obj, ICH9LPCPMRegs *pm)
     object_property_add_bool(obj, ACPI_PM_PROP_TCO_ENABLED,
                              ich9_pm_get_enable_tco,
                              ich9_pm_set_enable_tco);
+    object_property_add_bool(obj, "acpi-pci-hotplug-with-bridge-support",
+                             ich9_pm_get_acpi_pci_hotplug,
+                             ich9_pm_set_acpi_pci_hotplug);
 }
 
 void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
@@ -406,6 +461,11 @@ void ich9_pm_device_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
 {
     ICH9LPCState *lpc = ICH9_LPC_DEVICE(hotplug_dev);
 
+    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
+        acpi_pcihp_device_pre_plug_cb(hotplug_dev, dev, errp);
+        return;
+    }
+
     if (object_dynamic_cast(OBJECT(dev), TYPE_PC_DIMM) &&
         !lpc->pm.acpi_memory_hotplug.is_enabled) {
         error_setg(errp,
@@ -441,6 +501,9 @@ void ich9_pm_device_plug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
         } else {
             acpi_cpu_plug_cb(hotplug_dev, &lpc->pm.cpuhp_state, dev, errp);
         }
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
+        acpi_pcihp_device_plug_cb(hotplug_dev, &lpc->pm.acpi_pci_hotplug,
+                                  dev, errp);
     } else {
         error_setg(errp, "acpi: device plug request for not supported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -473,6 +536,10 @@ void ich9_pm_device_unplug_request_cb(HotplugHandler *hotplug_dev,
 
         acpi_cpu_unplug_request_cb(hotplug_dev, &lpc->pm.cpuhp_state,
                                    dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
+        acpi_pcihp_device_unplug_request_cb(hotplug_dev,
+                                            &lpc->pm.acpi_pci_hotplug,
+                                            dev, errp);
     } else {
         error_setg(errp, "acpi: device unplug request for not supported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
@@ -490,6 +557,9 @@ void ich9_pm_device_unplug_cb(HotplugHandler *hotplug_dev, DeviceState *dev,
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_CPU) &&
                !lpc->pm.cpu_hotplug_legacy) {
         acpi_cpu_unplug_cb(&lpc->pm.cpuhp_state, dev, errp);
+    } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
+        acpi_pcihp_device_unplug_cb(hotplug_dev, &lpc->pm.acpi_pci_hotplug,
+                                    dev, errp);
     } else {
         error_setg(errp, "acpi: device unplug for not supported device"
                    " type: %s", object_get_typename(OBJECT(dev)));
diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index 4999277..f4d706e 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -30,6 +30,9 @@
 #include "hw/pci-host/i440fx.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pci_bridge.h"
+#include "hw/pci/pci_host.h"
+#include "hw/pci/pcie_port.h"
+#include "hw/i386/acpi-build.h"
 #include "hw/acpi/acpi.h"
 #include "hw/pci/pci_bus.h"
 #include "migration/vmstate.h"
@@ -37,7 +40,6 @@
 #include "qom/qom-qobject.h"
 #include "trace.h"
 
-#define ACPI_PCIHP_ADDR 0xae00
 #define ACPI_PCIHP_SIZE 0x0018
 #define PCI_UP_BASE 0x0000
 #define PCI_DOWN_BASE 0x0004
@@ -104,6 +106,7 @@ static void *acpi_set_bsel(PCIBus *bus, void *opaque)
 static void acpi_set_pci_info(void)
 {
     static bool bsel_is_set;
+    Object *host = acpi_get_i386_pci_host();
     PCIBus *bus;
     unsigned bsel_alloc = ACPI_PCIHP_BSEL_DEFAULT;
 
@@ -112,7 +115,11 @@ static void acpi_set_pci_info(void)
     }
     bsel_is_set = true;
 
-    bus = find_i440fx(); /* TODO: Q35 support */
+    if (!host) {
+        return;
+    }
+
+    bus = PCI_HOST_BRIDGE(host)->bus;
     if (bus) {
         /* Scan all PCI buses. Set property to enable acpi based hotplug. */
         pci_for_each_bus_depth_first(bus, acpi_set_bsel, NULL, &bsel_alloc);
@@ -122,13 +129,14 @@ static void acpi_set_pci_info(void)
 static void acpi_pcihp_disable_root_bus(void)
 {
     static bool root_hp_disabled;
+    Object *host = acpi_get_i386_pci_host();
     PCIBus *bus;
 
     if (root_hp_disabled) {
         return;
     }
 
-    bus = find_i440fx();
+    bus = PCI_HOST_BRIDGE(host)->bus;
     if (bus) {
         /* setting the hotplug handler to NULL makes the bus non-hotpluggable */
         qbus_set_hotplug_handler(BUS(bus), NULL);
@@ -329,6 +337,13 @@ void acpi_pcihp_device_plug_cb(HotplugHandler *hotplug_dev, AcpiPciHpState *s,
             object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
             PCIBus *sec = pci_bridge_get_sec_bus(PCI_BRIDGE(pdev));
 
+            /* Remove all hot-plug handlers if hot-plug is disabled on slot */
+            if (object_dynamic_cast(OBJECT(dev), TYPE_PCIE_SLOT) &&
+                !PCIE_SLOT(pdev)->hotplug) {
+                qbus_set_hotplug_handler(BUS(sec), NULL);
+                return;
+            }
+
             qbus_set_hotplug_handler(BUS(sec), OBJECT(hotplug_dev));
             /* We don't have to overwrite any other hotplug handler yet */
             assert(QLIST_EMPTY(&sec->child));
@@ -488,10 +503,11 @@ static const MemoryRegionOps acpi_pcihp_io_ops = {
 };
 
 void acpi_pcihp_init(Object *owner, AcpiPciHpState *s, PCIBus *root_bus,
-                     MemoryRegion *address_space_io, bool bridges_enabled)
+                     MemoryRegion *address_space_io, bool bridges_enabled,
+                     uint16_t io_base)
 {
     s->io_len = ACPI_PCIHP_SIZE;
-    s->io_base = ACPI_PCIHP_ADDR;
+    s->io_base = io_base;
 
     s->root = root_bus;
     s->legacy_piix = !bridges_enabled;
diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 0bd23d7..48f7a1e 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -49,6 +49,8 @@
 #define GPE_BASE 0xafe0
 #define GPE_LEN 4
 
+#define ACPI_PCIHP_ADDR_PIIX4 0xae00
+
 struct pci_status {
     uint32_t up; /* deprecated, maintained for migration compatibility */
     uint32_t down;
@@ -607,7 +609,7 @@ static void piix4_acpi_system_hot_add_init(MemoryRegion *parent,
 
     if (s->use_acpi_hotplug_bridge || s->use_acpi_root_pci_hotplug) {
         acpi_pcihp_init(OBJECT(s), &s->acpi_pci_hotplug, bus, parent,
-                        s->use_acpi_hotplug_bridge);
+                        s->use_acpi_hotplug_bridge, ACPI_PCIHP_ADDR_PIIX4);
     }
 
     s->cpu_hotplug_legacy = true;
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index f102484..037cc1f 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -44,6 +44,7 @@
 #include "hw/acpi/tpm.h"
 #include "hw/pci/pcie_host.h"
 #include "hw/pci/pci.h"
+#include "hw/pci/pci_bus.h"
 #include "hw/pci-host/gpex.h"
 #include "hw/arm/virt.h"
 #include "hw/mem/nvdimm.h"
@@ -239,23 +240,89 @@ static void acpi_dsdt_add_tpm(Aml *scope, VirtMachineState *vms)
 }
 #endif
 
+/* Build the iort ID mapping to SMMUv3 for a given PCI host bridge */
+static int
+iort_host_bridges(Object *obj, void *opaque)
+{
+    GArray *idmap_blob = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
+        PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
+
+        if (bus && !pci_bus_bypass_iommu(bus)) {
+            int min_bus, max_bus;
+
+            pci_bus_range(bus, &min_bus, &max_bus);
+
+            AcpiIortIdMapping idmap = {
+                .input_base = min_bus << 8,
+                .id_count = (max_bus - min_bus + 1) << 8,
+            };
+            g_array_append_val(idmap_blob, idmap);
+        }
+    }
+
+    return 0;
+}
+
+static int iort_idmap_compare(gconstpointer a, gconstpointer b)
+{
+    AcpiIortIdMapping *idmap_a = (AcpiIortIdMapping *)a;
+    AcpiIortIdMapping *idmap_b = (AcpiIortIdMapping *)b;
+
+    return idmap_a->input_base - idmap_b->input_base;
+}
+
 static void
 build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
 {
-    int nb_nodes, iort_start = table_data->len;
+    int i, nb_nodes, rc_mapping_count, iort_start = table_data->len;
     AcpiIortIdMapping *idmap;
     AcpiIortItsGroup *its;
     AcpiIortTable *iort;
     AcpiIortSmmu3 *smmu;
     size_t node_size, iort_node_offset, iort_length, smmu_offset = 0;
     AcpiIortRC *rc;
+    GArray *smmu_idmaps = g_array_new(false, true, sizeof(AcpiIortIdMapping));
+    GArray *its_idmaps = g_array_new(false, true, sizeof(AcpiIortIdMapping));
 
     iort = acpi_data_push(table_data, sizeof(*iort));
 
     if (vms->iommu == VIRT_IOMMU_SMMUV3) {
+        AcpiIortIdMapping next_range = {0};
+
+        object_child_foreach_recursive(object_get_root(),
+                                       iort_host_bridges, smmu_idmaps);
+
+        /* Sort the smmu idmap by input_base */
+        g_array_sort(smmu_idmaps, iort_idmap_compare);
+
+        /*
+         * Split the whole RIDs by mapping from RC to SMMU,
+         * build the ID mapping from RC to ITS directly.
+         */
+        for (i = 0; i < smmu_idmaps->len; i++) {
+            idmap = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i);
+
+            if (next_range.input_base < idmap->input_base) {
+                next_range.id_count = idmap->input_base - next_range.input_base;
+                g_array_append_val(its_idmaps, next_range);
+            }
+
+            next_range.input_base = idmap->input_base + idmap->id_count;
+        }
+
+        /* Append the last RC -> ITS ID mapping */
+        if (next_range.input_base < 0xFFFF) {
+            next_range.id_count = 0xFFFF - next_range.input_base;
+            g_array_append_val(its_idmaps, next_range);
+        }
+
         nb_nodes = 3; /* RC, ITS, SMMUv3 */
+        rc_mapping_count = smmu_idmaps->len + its_idmaps->len;
     } else {
         nb_nodes = 2; /* RC, ITS */
+        rc_mapping_count = 1;
     }
 
     iort_length = sizeof(*iort);
@@ -307,13 +374,13 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     }
 
     /* Root Complex Node */
-    node_size = sizeof(*rc) + sizeof(*idmap);
+    node_size = sizeof(*rc) + sizeof(*idmap) * rc_mapping_count;
     iort_length += node_size;
     rc = acpi_data_push(table_data, node_size);
 
     rc->type = ACPI_IORT_NODE_PCI_ROOT_COMPLEX;
     rc->length = cpu_to_le16(node_size);
-    rc->mapping_count = cpu_to_le32(1);
+    rc->mapping_count = cpu_to_le32(rc_mapping_count);
     rc->mapping_offset = cpu_to_le32(sizeof(*rc));
 
     /* fully coherent device */
@@ -321,20 +388,45 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     rc->memory_properties.memory_flags = 0x3; /* CCA = CPM = DCAS = 1 */
     rc->pci_segment_number = 0; /* MCFG pci_segment */
 
-    /* Identity RID mapping covering the whole input RID range */
-    idmap = &rc->id_mapping_array[0];
-    idmap->input_base = 0;
-    idmap->id_count = cpu_to_le32(0xFFFF);
-    idmap->output_base = 0;
-
     if (vms->iommu == VIRT_IOMMU_SMMUV3) {
-        /* output IORT node is the smmuv3 node */
-        idmap->output_reference = cpu_to_le32(smmu_offset);
+        AcpiIortIdMapping *range;
+
+        /* translated RIDs connect to SMMUv3 node: RC -> SMMUv3 -> ITS */
+        for (i = 0; i < smmu_idmaps->len; i++) {
+            idmap = &rc->id_mapping_array[i];
+            range = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i);
+
+            idmap->input_base = cpu_to_le32(range->input_base);
+            idmap->id_count = cpu_to_le32(range->id_count);
+            idmap->output_base = cpu_to_le32(range->input_base);
+            /* output IORT node is the smmuv3 node */
+            idmap->output_reference = cpu_to_le32(smmu_offset);
+        }
+
+        /* bypassed RIDs connect to ITS group node directly: RC -> ITS */
+        for (i = 0; i < its_idmaps->len; i++) {
+            idmap = &rc->id_mapping_array[smmu_idmaps->len + i];
+            range = &g_array_index(its_idmaps, AcpiIortIdMapping, i);
+
+            idmap->input_base = cpu_to_le32(range->input_base);
+            idmap->id_count = cpu_to_le32(range->id_count);
+            idmap->output_base = cpu_to_le32(range->input_base);
+            /* output IORT node is the ITS group node (the first node) */
+            idmap->output_reference = cpu_to_le32(iort_node_offset);
+        }
     } else {
+        /* Identity RID mapping covering the whole input RID range */
+        idmap = &rc->id_mapping_array[0];
+        idmap->input_base = cpu_to_le32(0);
+        idmap->id_count = cpu_to_le32(0xFFFF);
+        idmap->output_base = cpu_to_le32(0);
         /* output IORT node is the ITS group node (the first node) */
         idmap->output_reference = cpu_to_le32(iort_node_offset);
     }
 
+    g_array_free(smmu_idmaps, true);
+    g_array_free(its_idmaps, true);
+
     /*
      * Update the pointer address in case table_data->data moves during above
      * acpi_data_push operations.
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 93ab9d2..81eda46 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -1367,6 +1367,7 @@ static void create_pcie(VirtMachineState *vms)
     }
 
     pci = PCI_HOST_BRIDGE(dev);
+    pci->bypass_iommu = vms->default_bus_bypass_iommu;
     vms->bus = pci->bus;
     if (vms->bus) {
         for (i = 0; i < nb_nics; i++) {
@@ -2322,6 +2323,21 @@ static void virt_set_iommu(Object *obj, const char *value, Error **errp)
     }
 }
 
+static bool virt_get_default_bus_bypass_iommu(Object *obj, Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    return vms->default_bus_bypass_iommu;
+}
+
+static void virt_set_default_bus_bypass_iommu(Object *obj, bool value,
+                                              Error **errp)
+{
+    VirtMachineState *vms = VIRT_MACHINE(obj);
+
+    vms->default_bus_bypass_iommu = value;
+}
+
 static CpuInstanceProperties
 virt_cpu_index_to_props(MachineState *ms, unsigned cpu_index)
 {
@@ -2661,6 +2677,13 @@ static void virt_machine_class_init(ObjectClass *oc, void *data)
                                           "Set the IOMMU type. "
                                           "Valid values are none and smmuv3");
 
+    object_class_property_add_bool(oc, "default_bus_bypass_iommu",
+                                   virt_get_default_bus_bypass_iommu,
+                                   virt_set_default_bus_bypass_iommu);
+    object_class_property_set_description(oc, "default_bus_bypass_iommu",
+                                          "Set on/off to enable/disable "
+                                          "bypass_iommu for default root bus");
+
     object_class_property_add_bool(oc, "ras", virt_get_ras,
                                    virt_set_ras);
     object_class_property_set_description(oc, "ras",
@@ -2728,6 +2751,9 @@ static void virt_instance_init(Object *obj)
     /* Default disallows iommu instantiation */
     vms->iommu = VIRT_IOMMU_NONE;
 
+    /* The default root bus is attached to iommu by default */
+    vms->default_bus_bypass_iommu = false;
+
     /* Default disallows RAS instantiation */
     vms->ras = false;
 
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 6f59fb0..775add0 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -584,7 +584,6 @@ static void machine_set_memdev(Object *obj, const char *value, Error **errp)
     ms->ram_memdev_id = g_strdup(value);
 }
 
-
 static void machine_init_notify(Notifier *notifier, void *data)
 {
     MachineState *machine = MACHINE(qdev_get_machine());
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 357437f..1783614 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -219,10 +219,6 @@ static void acpi_get_pm_info(MachineState *machine, AcpiPmInfo *pm)
         /* w2k requires FADT(rev1) or it won't boot, keep PC compatible */
         pm->fadt.rev = 1;
         pm->cpu_hp_io_base = PIIX4_CPU_HOTPLUG_IO_BASE;
-        pm->pcihp_io_base =
-            object_property_get_uint(obj, ACPI_PCIHP_IO_BASE_PROP, NULL);
-        pm->pcihp_io_len =
-            object_property_get_uint(obj, ACPI_PCIHP_IO_LEN_PROP, NULL);
     }
     if (lpc) {
         uint64_t smi_features = object_property_get_uint(lpc,
@@ -238,6 +234,10 @@ static void acpi_get_pm_info(MachineState *machine, AcpiPmInfo *pm)
         pm->smi_on_cpu_unplug =
             !!(smi_features & BIT_ULL(ICH9_LPC_SMI_F_CPU_HOT_UNPLUG_BIT));
     }
+    pm->pcihp_io_base =
+        object_property_get_uint(obj, ACPI_PCIHP_IO_BASE_PROP, NULL);
+    pm->pcihp_io_len =
+        object_property_get_uint(obj, ACPI_PCIHP_IO_LEN_PROP, NULL);
 
     /* The above need not be conditional on machine type because the reset port
      * happens to be the same on PIIX (pc) and ICH9 (q35). */
@@ -299,7 +299,7 @@ static void acpi_get_misc_info(AcpiMiscInfo *info)
  * Because of the PXB hosts we cannot simply query TYPE_PCI_HOST_BRIDGE.
  * On i386 arch we only have two pci hosts, so we can look only for them.
  */
-static Object *acpi_get_i386_pci_host(void)
+Object *acpi_get_i386_pci_host(void)
 {
     PCIHostState *host;
 
@@ -320,7 +320,10 @@ static void acpi_get_pci_holes(Range *hole, Range *hole64)
     Object *pci_host;
 
     pci_host = acpi_get_i386_pci_host();
-    g_assert(pci_host);
+
+    if (!pci_host) {
+        return;
+    }
 
     range_set_bounds1(hole,
                       object_property_get_uint(pci_host,
@@ -392,6 +395,9 @@ static void build_append_pci_bus_devices(Aml *parent_scope, PCIBus *bus,
 
         if (!pdev) {
             if (bsel) { /* add hotplug slots for non present devices */
+                if (pci_bus_is_express(bus) && slot > 0) {
+                    break;
+                }
                 dev = aml_device("S%.02X", PCI_DEVFN(slot, 0));
                 aml_append(dev, aml_name_decl("_SUN", aml_int(slot)));
                 aml_append(dev, aml_name_decl("_ADR", aml_int(slot << 16)));
@@ -521,7 +527,7 @@ 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)) {
+                if (pci_bus_is_root(sec)) {
                     continue;
                 }
 
@@ -1251,7 +1257,7 @@ static void build_piix4_isa_bridge(Aml *table)
     aml_append(table, scope);
 }
 
-static void build_piix4_pci_hotplug(Aml *table)
+static void build_x86_acpi_pci_hotplug(Aml *table, uint64_t pcihp_addr)
 {
     Aml *scope;
     Aml *field;
@@ -1260,20 +1266,22 @@ static void build_piix4_pci_hotplug(Aml *table)
     scope =  aml_scope("_SB.PCI0");
 
     aml_append(scope,
-        aml_operation_region("PCST", AML_SYSTEM_IO, aml_int(0xae00), 0x08));
+        aml_operation_region("PCST", AML_SYSTEM_IO, aml_int(pcihp_addr), 0x08));
     field = aml_field("PCST", AML_DWORD_ACC, AML_NOLOCK, AML_WRITE_AS_ZEROS);
     aml_append(field, aml_named_field("PCIU", 32));
     aml_append(field, aml_named_field("PCID", 32));
     aml_append(scope, field);
 
     aml_append(scope,
-        aml_operation_region("SEJ", AML_SYSTEM_IO, aml_int(0xae08), 0x04));
+        aml_operation_region("SEJ", AML_SYSTEM_IO,
+                             aml_int(pcihp_addr + ACPI_PCIHP_SEJ_BASE), 0x04));
     field = aml_field("SEJ", AML_DWORD_ACC, AML_NOLOCK, AML_WRITE_AS_ZEROS);
     aml_append(field, aml_named_field("B0EJ", 32));
     aml_append(scope, field);
 
     aml_append(scope,
-        aml_operation_region("BNMR", AML_SYSTEM_IO, aml_int(0xae10), 0x08));
+        aml_operation_region("BNMR", AML_SYSTEM_IO,
+                             aml_int(pcihp_addr + ACPI_PCIHP_BNMR_BASE), 0x08));
     field = aml_field("BNMR", AML_DWORD_ACC, AML_NOLOCK, AML_WRITE_AS_ZEROS);
     aml_append(field, aml_named_field("BNUM", 32));
     aml_append(field, aml_named_field("PIDX", 32));
@@ -1407,7 +1415,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         build_piix4_isa_bridge(dsdt);
         build_isa_devices_aml(dsdt);
         if (pm->pcihp_bridge_en || pm->pcihp_root_en) {
-            build_piix4_pci_hotplug(dsdt);
+            build_x86_acpi_pci_hotplug(dsdt, pm->pcihp_io_base);
         }
         build_piix4_pci0_int(dsdt);
     } else {
@@ -1455,6 +1463,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         }
         build_q35_isa_bridge(dsdt);
         build_isa_devices_aml(dsdt);
+        if (pm->pcihp_bridge_en) {
+            build_x86_acpi_pci_hotplug(dsdt, pm->pcihp_io_base);
+        }
         build_q35_pci0_int(dsdt);
         if (pcms->smbus && !pcmc->do_not_add_smb_acpi) {
             build_smb0(dsdt, pcms->smbus, ICH9_SMB_DEV, ICH9_SMB_FUNC);
@@ -1489,7 +1500,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
     {
         aml_append(scope, aml_name_decl("_HID", aml_string("ACPI0006")));
 
-        if (misc->is_piix4 && (pm->pcihp_bridge_en || pm->pcihp_root_en)) {
+        if (pm->pcihp_bridge_en || pm->pcihp_root_en) {
             method = aml_method("_E01", 0, AML_NOTSERIALIZED);
             aml_append(method,
                 aml_acquire(aml_name("\\_SB.PCI0.BLCK"), 0xFFFF));
@@ -1757,6 +1768,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
         PCIBus *bus = NULL;
 
         pci_host = acpi_get_i386_pci_host();
+
         if (pci_host) {
             bus = PCI_HOST_BRIDGE(pci_host)->bus;
         }
@@ -2011,6 +2023,56 @@ build_srat(GArray *table_data, BIOSLinker *linker, MachineState *machine)
 }
 
 /*
+ * Insert DMAR scope for PCI bridges and endpoint devcie
+ */
+static void
+insert_scope(PCIBus *bus, PCIDevice *dev, void *opaque)
+{
+    GArray *scope_blob = opaque;
+    AcpiDmarDeviceScope *scope = NULL;
+
+    if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_BRIDGE)) {
+        /* Dmar Scope Type: 0x02 for PCI Bridge */
+        build_append_int_noprefix(scope_blob, 0x02, 1);
+    } else {
+        /* Dmar Scope Type: 0x01 for PCI Endpoint Device */
+        build_append_int_noprefix(scope_blob, 0x01, 1);
+    }
+
+    /* length */
+    build_append_int_noprefix(scope_blob,
+                              sizeof(*scope) + sizeof(scope->path[0]), 1);
+    /* reserved */
+    build_append_int_noprefix(scope_blob, 0, 2);
+    /* enumeration_id */
+    build_append_int_noprefix(scope_blob, 0, 1);
+    /* bus */
+    build_append_int_noprefix(scope_blob, pci_bus_num(bus), 1);
+    /* device */
+    build_append_int_noprefix(scope_blob, PCI_SLOT(dev->devfn), 1);
+    /* function */
+    build_append_int_noprefix(scope_blob, PCI_FUNC(dev->devfn), 1);
+}
+
+/* For a given PCI host bridge, walk and insert DMAR scope */
+static int
+dmar_host_bridges(Object *obj, void *opaque)
+{
+    GArray *scope_blob = opaque;
+
+    if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
+        PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
+
+        if (bus && !pci_bus_bypass_iommu(bus)) {
+            pci_for_each_device(bus, pci_bus_num(bus), insert_scope,
+                                scope_blob);
+        }
+    }
+
+    return 0;
+}
+
+/*
  * VT-d spec 8.1 DMA Remapping Reporting Structure
  * (version Oct. 2014 or later)
  */
@@ -2029,6 +2091,15 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker, const char *oem_id,
     /* Root complex IOAPIC use one path[0] only */
     size_t ioapic_scope_size = sizeof(*scope) + sizeof(scope->path[0]);
     IntelIOMMUState *intel_iommu = INTEL_IOMMU_DEVICE(iommu);
+    GArray *scope_blob = g_array_new(false, true, 1);
+
+    /*
+     * A PCI bus walk, for each PCI host bridge.
+     * Insert scope for each PCI bridge and endpoint device which
+     * is attached to a bus with iommu enabled.
+     */
+    object_child_foreach_recursive(object_get_root(),
+                                   dmar_host_bridges, scope_blob);
 
     assert(iommu);
     if (x86_iommu_ir_supported(iommu)) {
@@ -2042,8 +2113,9 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker, const char *oem_id,
     /* DMAR Remapping Hardware Unit Definition structure */
     drhd = acpi_data_push(table_data, sizeof(*drhd) + ioapic_scope_size);
     drhd->type = cpu_to_le16(ACPI_DMAR_TYPE_HARDWARE_UNIT);
-    drhd->length = cpu_to_le16(sizeof(*drhd) + ioapic_scope_size);
-    drhd->flags = ACPI_DMAR_INCLUDE_PCI_ALL;
+    drhd->length =
+        cpu_to_le16(sizeof(*drhd) + ioapic_scope_size + scope_blob->len);
+    drhd->flags = 0;            /* Don't include all pci device */
     drhd->pci_segment = cpu_to_le16(0);
     drhd->address = cpu_to_le64(Q35_HOST_BRIDGE_IOMMU_ADDR);
 
@@ -2057,6 +2129,10 @@ build_dmar_q35(GArray *table_data, BIOSLinker *linker, const char *oem_id,
     scope->path[0].device = PCI_SLOT(Q35_PSEUDO_DEVFN_IOAPIC);
     scope->path[0].function = PCI_FUNC(Q35_PSEUDO_DEVFN_IOAPIC);
 
+    /* Add scope found above */
+    g_array_append_vals(table_data, scope_blob->data, scope_blob->len);
+    g_array_free(scope_blob, true);
+
     if (iommu->dt_supported) {
         atsr = acpi_data_push(table_data, sizeof(*atsr));
         atsr->type = cpu_to_le16(ACPI_DMAR_TYPE_ATSR);
@@ -2187,7 +2263,7 @@ ivrs_host_bridges(Object *obj, void *opaque)
     if (object_dynamic_cast(obj, TYPE_PCI_HOST_BRIDGE)) {
         PCIBus *bus = PCI_HOST_BRIDGE(obj)->bus;
 
-        if (bus) {
+        if (bus && !pci_bus_bypass_iommu(bus)) {
             pci_for_each_device(bus, pci_bus_num(bus), insert_ivhd, ivhd_blob);
         }
     }
@@ -2313,7 +2389,9 @@ static bool acpi_get_mcfg(AcpiMcfgInfo *mcfg)
     QObject *o;
 
     pci_host = acpi_get_i386_pci_host();
-    g_assert(pci_host);
+    if (!pci_host) {
+        return false;
+    }
 
     o = object_property_get_qobject(pci_host, PCIE_HOST_MCFG_BASE, NULL);
     if (!o) {
@@ -2343,7 +2421,7 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine)
     AcpiPmInfo pm;
     AcpiMiscInfo misc;
     AcpiMcfgInfo mcfg;
-    Range pci_hole, pci_hole64;
+    Range pci_hole = {}, pci_hole64 = {};
     uint8_t *u;
     size_t aml_len = 0;
     GArray *tables_blob = tables->table_data;
diff --git a/hw/i386/acpi-build.h b/hw/i386/acpi-build.h
index 74df5fc..0dce155 100644
--- a/hw/i386/acpi-build.h
+++ b/hw/i386/acpi-build.h
@@ -5,6 +5,11 @@
 
 extern const struct AcpiGenericAddress x86_nvdimm_acpi_dsmio;
 
+/* PCI Hot-plug registers bases. See docs/spec/acpi_pci_hotplug.txt */
+#define ACPI_PCIHP_SEJ_BASE 0x8
+#define ACPI_PCIHP_BNMR_BASE 0x10
+
 void acpi_setup(void);
+Object *acpi_get_i386_pci_host(void);
 
 #endif
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index aa79c5e..c2b9d62 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -99,6 +99,7 @@ GlobalProperty pc_compat_6_0[] = {
     { "qemu64" "-" TYPE_X86_CPU, "model", "6" },
     { "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
     { TYPE_X86_CPU, "x-vendor-cpuid-only", "off" },
+    { "ICH9-LPC", "acpi-pci-hotplug-with-bridge-support", "off" },
 };
 const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
 
@@ -1523,6 +1524,21 @@ static void pc_machine_set_hpet(Object *obj, bool value, Error **errp)
     pcms->hpet_enabled = value;
 }
 
+static bool pc_machine_get_default_bus_bypass_iommu(Object *obj, Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    return pcms->default_bus_bypass_iommu;
+}
+
+static void pc_machine_set_default_bus_bypass_iommu(Object *obj, bool value,
+                                                    Error **errp)
+{
+    PCMachineState *pcms = PC_MACHINE(obj);
+
+    pcms->default_bus_bypass_iommu = value;
+}
+
 static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
                                             const char *name, void *opaque,
                                             Error **errp)
@@ -1622,6 +1638,7 @@ static void pc_machine_initfn(Object *obj)
 #ifdef CONFIG_HPET
     pcms->hpet_enabled = true;
 #endif
+    pcms->default_bus_bypass_iommu = false;
 
     pc_system_flash_create(pcms);
     pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
@@ -1746,6 +1763,10 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
     object_class_property_add_bool(oc, "hpet",
         pc_machine_get_hpet, pc_machine_set_hpet);
 
+    object_class_property_add_bool(oc, "default_bus_bypass_iommu",
+        pc_machine_get_default_bus_bypass_iommu,
+        pc_machine_set_default_bus_bypass_iommu);
+
     object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
         pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
         NULL, NULL);
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index 46a0f19..04b4a47 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -37,6 +37,7 @@
 #include "sysemu/kvm.h"
 #include "hw/kvm/clock.h"
 #include "hw/pci-host/q35.h"
+#include "hw/pci/pcie_port.h"
 #include "hw/qdev-properties.h"
 #include "hw/i386/x86.h"
 #include "hw/i386/pc.h"
@@ -136,6 +137,7 @@ static void pc_q35_init(MachineState *machine)
     ram_addr_t lowmem;
     DriveInfo *hd[MAX_SATA_PORTS];
     MachineClass *mc = MACHINE_GET_CLASS(machine);
+    bool acpi_pcihp;
 
     /* Check whether RAM fits below 4G (leaving 1/2 GByte for IO memory
      * and 256 Mbytes for PCI Express Enhanced Configuration Access Mapping
@@ -236,6 +238,15 @@ static void pc_q35_init(MachineState *machine)
     object_property_set_link(OBJECT(machine), PC_MACHINE_ACPI_DEVICE_PROP,
                              OBJECT(lpc), &error_abort);
 
+    acpi_pcihp = object_property_get_bool(OBJECT(lpc),
+                                          "acpi-pci-hotplug-with-bridge-support",
+                                          NULL);
+
+    if (acpi_pcihp) {
+        object_register_sugar_prop(TYPE_PCIE_SLOT, "native-hotplug",
+                                   "false", true);
+    }
+
     /* irq lines */
     gsi_state = pc_gsi_create(&x86ms->gsi, pcmc->pci_enabled);
 
diff --git a/hw/pci-bridge/pci_expander_bridge.c b/hw/pci-bridge/pci_expander_bridge.c
index aedded1..7112dc3 100644
--- a/hw/pci-bridge/pci_expander_bridge.c
+++ b/hw/pci-bridge/pci_expander_bridge.c
@@ -57,6 +57,7 @@ struct PXBDev {
 
     uint8_t bus_nr;
     uint16_t numa_node;
+    bool bypass_iommu;
 };
 
 static PXBDev *convert_to_pxb(PCIDevice *dev)
@@ -255,6 +256,7 @@ static void pxb_dev_realize_common(PCIDevice *dev, bool pcie, Error **errp)
     bus->map_irq = pxb_map_irq_fn;
 
     PCI_HOST_BRIDGE(ds)->bus = bus;
+    PCI_HOST_BRIDGE(ds)->bypass_iommu = pxb->bypass_iommu;
 
     pxb_register_bus(dev, bus, &local_err);
     if (local_err) {
@@ -301,6 +303,7 @@ static Property pxb_dev_properties[] = {
     /* Note: 0 is not a legal PXB bus number. */
     DEFINE_PROP_UINT8("bus_nr", PXBDev, bus_nr, 0),
     DEFINE_PROP_UINT16("numa_node", PXBDev, numa_node, NUMA_NODE_UNASSIGNED),
+    DEFINE_PROP_BOOL("bypass_iommu", PXBDev, bypass_iommu, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 0f37cf0..ab5a47a 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -65,6 +65,8 @@ static void q35_host_realize(DeviceState *dev, Error **errp)
                                 s->mch.address_space_io,
                                 0, TYPE_PCIE_BUS);
     PC_MACHINE(qdev_get_machine())->bus = pci->bus;
+    pci->bypass_iommu =
+        PC_MACHINE(qdev_get_machine())->default_bus_bypass_iommu;
     qdev_realize(DEVICE(&s->mch), BUS(pci->bus), &error_fatal);
 }
 
diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 377084f..23d2ae2 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -416,6 +416,22 @@ const char *pci_root_bus_path(PCIDevice *dev)
     return rootbus->qbus.name;
 }
 
+bool pci_bus_bypass_iommu(PCIBus *bus)
+{
+    PCIBus *rootbus = bus;
+    PCIHostState *host_bridge;
+
+    if (!pci_bus_is_root(bus)) {
+        rootbus = pci_device_root_bus(bus->parent_dev);
+    }
+
+    host_bridge = PCI_HOST_BRIDGE(rootbus->qbus.parent);
+
+    assert(host_bridge->bus == rootbus);
+
+    return host_bridge->bypass_iommu;
+}
+
 static void pci_root_bus_init(PCIBus *bus, DeviceState *parent,
                               MemoryRegion *address_space_mem,
                               MemoryRegion *address_space_io,
@@ -521,6 +537,22 @@ int pci_bus_num(PCIBus *s)
     return PCI_BUS_GET_CLASS(s)->bus_num(s);
 }
 
+/* Returns the min and max bus numbers of a PCI bus hierarchy */
+void pci_bus_range(PCIBus *bus, int *min_bus, int *max_bus)
+{
+    int i;
+    *min_bus = *max_bus = pci_bus_num(bus);
+
+    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
+        PCIDevice *dev = bus->devices[i];
+
+        if (dev && PCI_DEVICE_GET_CLASS(dev)->is_bridge) {
+            *min_bus = MIN(*min_bus, dev->config[PCI_SECONDARY_BUS]);
+            *max_bus = MAX(*max_bus, dev->config[PCI_SUBORDINATE_BUS]);
+        }
+    }
+}
+
 int pci_bus_numa_node(PCIBus *bus)
 {
     return PCI_BUS_GET_CLASS(bus)->numa_node(bus);
@@ -2718,7 +2750,7 @@ AddressSpace *pci_device_iommu_address_space(PCIDevice *dev)
 
         iommu_bus = parent_bus;
     }
-    if (iommu_bus && iommu_bus->iommu_fn) {
+    if (!pci_bus_bypass_iommu(bus) && iommu_bus && iommu_bus->iommu_fn) {
         return iommu_bus->iommu_fn(bus, iommu_bus->iommu_opaque, devfn);
     }
     return &address_space_memory;
diff --git a/hw/pci/pci_host.c b/hw/pci/pci_host.c
index 8ca5fad..cf02f0d 100644
--- a/hw/pci/pci_host.c
+++ b/hw/pci/pci_host.c
@@ -222,6 +222,7 @@ const VMStateDescription vmstate_pcihost = {
 static Property pci_host_properties_common[] = {
     DEFINE_PROP_BOOL("x-config-reg-migration-enabled", PCIHostState,
                      mig_enabled, true),
+    DEFINE_PROP_BOOL("bypass-iommu", PCIHostState, bypass_iommu, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
index fd0fa15..6e95d82 100644
--- a/hw/pci/pcie.c
+++ b/hw/pci/pcie.c
@@ -529,7 +529,13 @@ void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
                                PCI_EXP_SLTCAP_PIP |
                                PCI_EXP_SLTCAP_AIP |
                                PCI_EXP_SLTCAP_ABP);
-    if (s->hotplug) {
+
+    /*
+     * Enable native hot-plug on all hot-plugged bridges unless
+     * hot-plug is disabled on the slot.
+     */
+    if (s->hotplug &&
+        (s->native_hotplug || DEVICE(dev)->hotplugged)) {
         pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
                                    PCI_EXP_SLTCAP_HPS |
                                    PCI_EXP_SLTCAP_HPC);
diff --git a/hw/pci/pcie_port.c b/hw/pci/pcie_port.c
index eb563ad..da850e8 100644
--- a/hw/pci/pcie_port.c
+++ b/hw/pci/pcie_port.c
@@ -148,6 +148,7 @@ static Property pcie_slot_props[] = {
     DEFINE_PROP_UINT8("chassis", PCIESlot, chassis, 0),
     DEFINE_PROP_UINT16("slot", PCIESlot, slot, 0),
     DEFINE_PROP_BOOL("hotplug", PCIESlot, hotplug, true),
+    DEFINE_PROP_BOOL("native-hotplug", PCIESlot, native_hotplug, true),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/hw/virtio/Kconfig b/hw/virtio/Kconfig
index 0eda25c..35ab45e 100644
--- a/hw/virtio/Kconfig
+++ b/hw/virtio/Kconfig
@@ -58,3 +58,8 @@ config VIRTIO_MEM
     depends on LINUX
     depends on VIRTIO_MEM_SUPPORTED
     select MEM_DEVICE
+
+config VHOST_USER_I2C
+    bool
+    default y
+    depends on VIRTIO && VHOST_USER
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index fbff9bc..bc352a6 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -25,6 +25,8 @@ virtio_ss.add(when: 'CONFIG_VHOST_USER_VSOCK', if_true: files('vhost-user-vsock.
 virtio_ss.add(when: 'CONFIG_VIRTIO_RNG', if_true: files('virtio-rng.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_IOMMU', if_true: files('virtio-iommu.c'))
 virtio_ss.add(when: 'CONFIG_VIRTIO_MEM', if_true: files('virtio-mem.c'))
+virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
+virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_I2C'], if_true: files('vhost-user-i2c-pci.c'))
 
 virtio_pci_ss = ss.source_set()
 virtio_pci_ss.add(when: 'CONFIG_VHOST_VSOCK', if_true: files('vhost-vsock-pci.c'))
diff --git a/hw/virtio/vhost-user-i2c-pci.c b/hw/virtio/vhost-user-i2c-pci.c
new file mode 100644
index 0000000..70b7b65
--- /dev/null
+++ b/hw/virtio/vhost-user-i2c-pci.c
@@ -0,0 +1,69 @@
+/*
+ * Vhost-user i2c virtio device PCI glue
+ *
+ * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/vhost-user-i2c.h"
+#include "virtio-pci.h"
+
+struct VHostUserI2CPCI {
+    VirtIOPCIProxy parent_obj;
+    VHostUserI2C vdev;
+};
+
+typedef struct VHostUserI2CPCI VHostUserI2CPCI;
+
+#define TYPE_VHOST_USER_I2C_PCI "vhost-user-i2c-pci-base"
+
+DECLARE_INSTANCE_CHECKER(VHostUserI2CPCI, VHOST_USER_I2C_PCI,
+                         TYPE_VHOST_USER_I2C_PCI)
+
+static void vhost_user_i2c_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
+{
+    VHostUserI2CPCI *dev = VHOST_USER_I2C_PCI(vpci_dev);
+    DeviceState *vdev = DEVICE(&dev->vdev);
+
+    vpci_dev->nvectors = 1;
+    qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
+}
+
+static void vhost_user_i2c_pci_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass);
+    PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass);
+    k->realize = vhost_user_i2c_pci_realize;
+    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+    pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
+    pcidev_k->device_id = 0; /* Set by virtio-pci based on virtio id */
+    pcidev_k->revision = 0x00;
+    pcidev_k->class_id = PCI_CLASS_COMMUNICATION_OTHER;
+}
+
+static void vhost_user_i2c_pci_instance_init(Object *obj)
+{
+    VHostUserI2CPCI *dev = VHOST_USER_I2C_PCI(obj);
+
+    virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev),
+                                TYPE_VHOST_USER_I2C);
+}
+
+static const VirtioPCIDeviceTypeInfo vhost_user_i2c_pci_info = {
+    .base_name = TYPE_VHOST_USER_I2C_PCI,
+    .non_transitional_name = "vhost-user-i2c-pci",
+    .instance_size = sizeof(VHostUserI2CPCI),
+    .instance_init = vhost_user_i2c_pci_instance_init,
+    .class_init = vhost_user_i2c_pci_class_init,
+};
+
+static void vhost_user_i2c_pci_register(void)
+{
+    virtio_pci_types_register(&vhost_user_i2c_pci_info);
+}
+
+type_init(vhost_user_i2c_pci_register);
diff --git a/hw/virtio/vhost-user-i2c.c b/hw/virtio/vhost-user-i2c.c
new file mode 100644
index 0000000..d172632
--- /dev/null
+++ b/hw/virtio/vhost-user-i2c.c
@@ -0,0 +1,288 @@
+/*
+ * Vhost-user i2c virtio device
+ *
+ * Copyright (c) 2021 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "hw/qdev-properties.h"
+#include "hw/virtio/virtio-bus.h"
+#include "hw/virtio/vhost-user-i2c.h"
+#include "qemu/error-report.h"
+#include "standard-headers/linux/virtio_ids.h"
+
+/* Remove this once the header is updated in Linux kernel */
+#ifndef VIRTIO_ID_I2C_ADAPTER
+#define VIRTIO_ID_I2C_ADAPTER                34
+#endif
+
+static void vu_i2c_start(VirtIODevice *vdev)
+{
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    int ret, i;
+
+    if (!k->set_guest_notifiers) {
+        error_report("binding does not support guest notifiers");
+        return;
+    }
+
+    ret = vhost_dev_enable_notifiers(&i2c->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error enabling host notifiers: %d", -ret);
+        return;
+    }
+
+    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, true);
+    if (ret < 0) {
+        error_report("Error binding guest notifier: %d", -ret);
+        goto err_host_notifiers;
+    }
+
+    i2c->vhost_dev.acked_features = vdev->guest_features;
+
+    ret = vhost_dev_start(&i2c->vhost_dev, vdev);
+    if (ret < 0) {
+        error_report("Error starting vhost-user-i2c: %d", -ret);
+        goto err_guest_notifiers;
+    }
+
+    /*
+     * guest_notifier_mask/pending not used yet, so just unmask
+     * everything here. virtio-pci will do the right thing by
+     * enabling/disabling irqfd.
+     */
+    for (i = 0; i < i2c->vhost_dev.nvqs; i++) {
+        vhost_virtqueue_mask(&i2c->vhost_dev, vdev, i, false);
+    }
+
+    return;
+
+err_guest_notifiers:
+    k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
+err_host_notifiers:
+    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
+}
+
+static void vu_i2c_stop(VirtIODevice *vdev)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
+    VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
+    int ret;
+
+    if (!k->set_guest_notifiers) {
+        return;
+    }
+
+    vhost_dev_stop(&i2c->vhost_dev, vdev);
+
+    ret = k->set_guest_notifiers(qbus->parent, i2c->vhost_dev.nvqs, false);
+    if (ret < 0) {
+        error_report("vhost guest notifier cleanup failed: %d", ret);
+        return;
+    }
+
+    vhost_dev_disable_notifiers(&i2c->vhost_dev, vdev);
+}
+
+static void vu_i2c_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+    bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
+
+    if (!vdev->vm_running) {
+        should_start = false;
+    }
+
+    if (i2c->vhost_dev.started == should_start) {
+        return;
+    }
+
+    if (should_start) {
+        vu_i2c_start(vdev);
+    } else {
+        vu_i2c_stop(vdev);
+    }
+}
+
+static uint64_t vu_i2c_get_features(VirtIODevice *vdev,
+                                    uint64_t requested_features, Error **errp)
+{
+    /* No feature bits used yet */
+    return requested_features;
+}
+
+static void vu_i2c_handle_output(VirtIODevice *vdev, VirtQueue *vq)
+{
+    /*
+     * Not normally called; it's the daemon that handles the queue;
+     * however virtio's cleanup path can call this.
+     */
+}
+
+static void vu_i2c_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    vhost_virtqueue_mask(&i2c->vhost_dev, vdev, idx, mask);
+}
+
+static bool vu_i2c_guest_notifier_pending(VirtIODevice *vdev, int idx)
+{
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    return vhost_virtqueue_pending(&i2c->vhost_dev, idx);
+}
+
+static void do_vhost_user_cleanup(VirtIODevice *vdev, VHostUserI2C *i2c)
+{
+    vhost_user_cleanup(&i2c->vhost_user);
+    virtio_delete_queue(i2c->vq);
+    virtio_cleanup(vdev);
+    g_free(i2c->vhost_dev.vqs);
+    i2c->vhost_dev.vqs = NULL;
+}
+
+static int vu_i2c_connect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    if (i2c->connected) {
+        return 0;
+    }
+    i2c->connected = true;
+
+    /* restore vhost state */
+    if (virtio_device_started(vdev, vdev->status)) {
+        vu_i2c_start(vdev);
+    }
+
+    return 0;
+}
+
+static void vu_i2c_disconnect(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    if (!i2c->connected) {
+        return;
+    }
+    i2c->connected = false;
+
+    if (i2c->vhost_dev.started) {
+        vu_i2c_stop(vdev);
+    }
+}
+
+static void vu_i2c_event(void *opaque, QEMUChrEvent event)
+{
+    DeviceState *dev = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(vdev);
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+        if (vu_i2c_connect(dev) < 0) {
+            qemu_chr_fe_disconnect(&i2c->chardev);
+            return;
+        }
+        break;
+    case CHR_EVENT_CLOSED:
+        vu_i2c_disconnect(dev);
+        break;
+    case CHR_EVENT_BREAK:
+    case CHR_EVENT_MUX_IN:
+    case CHR_EVENT_MUX_OUT:
+        /* Ignore */
+        break;
+    }
+}
+
+static void vu_i2c_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
+    int ret;
+
+    if (!i2c->chardev.chr) {
+        error_setg(errp, "vhost-user-i2c: missing chardev");
+        return;
+    }
+
+    if (!vhost_user_init(&i2c->vhost_user, &i2c->chardev, errp)) {
+        return;
+    }
+
+    virtio_init(vdev, "vhost-user-i2c", VIRTIO_ID_I2C_ADAPTER, 0);
+
+    i2c->vhost_dev.nvqs = 1;
+    i2c->vq = virtio_add_queue(vdev, 4, vu_i2c_handle_output);
+    i2c->vhost_dev.vqs = g_new0(struct vhost_virtqueue, i2c->vhost_dev.nvqs);
+
+    ret = vhost_dev_init(&i2c->vhost_dev, &i2c->vhost_user,
+                         VHOST_BACKEND_TYPE_USER, 0, errp);
+    if (ret < 0) {
+        do_vhost_user_cleanup(vdev, i2c);
+    }
+
+    qemu_chr_fe_set_handlers(&i2c->chardev, NULL, NULL, vu_i2c_event, NULL,
+                             dev, NULL, true);
+}
+
+static void vu_i2c_device_unrealize(DeviceState *dev)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VHostUserI2C *i2c = VHOST_USER_I2C(dev);
+
+    /* This will stop vhost backend if appropriate. */
+    vu_i2c_set_status(vdev, 0);
+    vhost_dev_cleanup(&i2c->vhost_dev);
+    do_vhost_user_cleanup(vdev, i2c);
+}
+
+static const VMStateDescription vu_i2c_vmstate = {
+    .name = "vhost-user-i2c",
+    .unmigratable = 1,
+};
+
+static Property vu_i2c_properties[] = {
+    DEFINE_PROP_CHR("chardev", VHostUserI2C, chardev),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void vu_i2c_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+
+    device_class_set_props(dc, vu_i2c_properties);
+    dc->vmsd = &vu_i2c_vmstate;
+    set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
+    vdc->realize = vu_i2c_device_realize;
+    vdc->unrealize = vu_i2c_device_unrealize;
+    vdc->get_features = vu_i2c_get_features;
+    vdc->set_status = vu_i2c_set_status;
+    vdc->guest_notifier_mask = vu_i2c_guest_notifier_mask;
+    vdc->guest_notifier_pending = vu_i2c_guest_notifier_pending;
+}
+
+static const TypeInfo vu_i2c_info = {
+    .name = TYPE_VHOST_USER_I2C,
+    .parent = TYPE_VIRTIO_DEVICE,
+    .instance_size = sizeof(VHostUserI2C),
+    .class_init = vu_i2c_class_init,
+};
+
+static void vu_i2c_register_types(void)
+{
+    type_register_static(&vu_i2c_info);
+}
+
+type_init(vu_i2c_register_types)
diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
index 777cafe..1b1a5c7 100644
--- a/hw/virtio/vhost-vsock.c
+++ b/hw/virtio/vhost-vsock.c
@@ -21,6 +21,11 @@
 #include "hw/virtio/vhost-vsock.h"
 #include "monitor/monitor.h"
 
+const int feature_bits[] = {
+    VIRTIO_VSOCK_F_SEQPACKET,
+    VHOST_INVALID_FEATURE_BIT
+};
+
 static void vhost_vsock_get_config(VirtIODevice *vdev, uint8_t *config)
 {
     VHostVSock *vsock = VHOST_VSOCK(vdev);
@@ -108,8 +113,11 @@ static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
                                          uint64_t requested_features,
                                          Error **errp)
 {
-    /* No feature bits used yet */
-    return requested_features;
+    VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
+
+    virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_SEQPACKET);
+    return vhost_get_features(&vvc->vhost_dev, feature_bits,
+                                requested_features);
 }
 
 static const VMStateDescription vmstate_virtio_vhost_vsock = {