diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index c41d5f9778..f64ff42ab5 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -78,6 +78,8 @@
 #include "hw/virtio/virtio-iommu.h"
 #include "hw/char/pl011.h"
 #include "qemu/guest-random.h"
+#include "hw/pci/pci_bus.h"
+#include "hw/pci/pcie_host.h"
 
 #define DEFINE_VIRT_MACHINE_LATEST(major, minor, latest) \
     static void virt_##major##_##minor##_class_init(ObjectClass *oc, \
@@ -1457,6 +1459,10 @@ void virt_machine_done(Notifier *notifier, void *data)
     ARMCPU *cpu = ARM_CPU(first_cpu);
     struct arm_boot_info *info = &vms->bootinfo;
     AddressSpace *as = arm_boot_address_space(cpu, info);
+    PCIHostState *s = PCI_GET_PCIE_HOST_STATE;
+
+    PCIBus *bus = s->bus;
+    FWCfgState *fw_cfg = vms->fw_cfg;
 
     /*
      * If the user provided a dtb, we assume the dynamic sysbus nodes
@@ -1475,6 +1481,8 @@ void virt_machine_done(Notifier *notifier, void *data)
         exit(1);
     }
 
+    fw_cfg_write_extra_pci_roots(bus, fw_cfg);
+
     virt_acpi_setup(vms);
     virt_build_smbios(vms);
 }
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2128f3d6fe..3227e0d2ea 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -842,26 +842,12 @@ void pc_machine_done(Notifier *notifier, void *data)
                                         PCMachineState, machine_done);
     X86MachineState *x86ms = X86_MACHINE(pcms);
     PCIBus *bus = pcms->bus;
+    FWCfgState *fw_cfg = pcms->fw_cfg;
 
     /* set the number of CPUs */
     rtc_set_cpus_count(x86ms->rtc, x86ms->boot_cpus);
 
-    if (bus) {
-        int extra_hosts = 0;
-
-        QLIST_FOREACH(bus, &bus->child, sibling) {
-            /* look for expander root buses */
-            if (pci_bus_is_root(bus)) {
-                extra_hosts++;
-            }
-        }
-        if (extra_hosts && x86ms->fw_cfg) {
-            uint64_t *val = g_malloc(sizeof(*val));
-            *val = cpu_to_le64(extra_hosts);
-            fw_cfg_add_file(x86ms->fw_cfg,
-                    "etc/extra-pci-roots", val, sizeof(*val));
-        }
-    }
+    fw_cfg_write_extra_pci_roots(bus, fw_cfg);
 
     acpi_setup();
     if (x86ms->fw_cfg) {
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 8dd50c2c72..824cfcf054 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -40,6 +40,7 @@
 #include "qemu/cutils.h"
 #include "qapi/error.h"
 #include "hw/acpi/aml-build.h"
+#include "hw/pci/pci_bus.h"
 
 #define FW_CFG_FILE_SLOTS_DFLT 0x20
 
@@ -742,6 +743,25 @@ static void *fw_cfg_modify_bytes_read(FWCfgState *s, uint16_t key,
     return ptr;
 }
 
+void fw_cfg_write_extra_pci_roots(PCIBus *bus, FWCfgState *s)
+{
+    if (bus) {
+        int extra_hosts = 0;
+        QLIST_FOREACH(bus, &bus->child, sibling) {
+            /* look for expander root buses */
+            if (pci_bus_is_root(bus)) {
+                extra_hosts++;
+            }
+        }
+        if (extra_hosts && s) {
+            uint64_t *val = g_malloc(sizeof(*val));
+            *val = cpu_to_le64(extra_hosts);
+            fw_cfg_add_file(s,
+                   "etc/extra-pci-roots", val, sizeof(*val));
+        }
+    }
+}
+
 void fw_cfg_add_bytes(FWCfgState *s, uint16_t key, void *data, size_t len)
 {
     trace_fw_cfg_add_bytes(key, trace_key_name(key), len);
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index 25d9307018..eb86ee5ae6 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -79,6 +79,8 @@ struct FWCfgMemState {
     MemoryRegionOps wide_data_ops;
 };
 
+void fw_cfg_write_extra_pci_roots(PCIBus *bus, FWCfgState *s);
+
 /**
  * fw_cfg_add_bytes:
  * @s: fw_cfg device being modified
diff --git a/include/hw/pci/pcie_host.h b/include/hw/pci/pcie_host.h
index 3f7b9886d1..c93f2d7011 100644
--- a/include/hw/pci/pcie_host.h
+++ b/include/hw/pci/pcie_host.h
@@ -27,6 +27,10 @@
 #define TYPE_PCIE_HOST_BRIDGE "pcie-host-bridge"
 #define PCIE_HOST_BRIDGE(obj) \
     OBJECT_CHECK(PCIExpressHost, (obj), TYPE_PCIE_HOST_BRIDGE)
+#define PCI_GET_PCIE_HOST_STATE \
+    OBJECT_CHECK(PCIHostState, \
+                 object_resolve_path_type("", "pcie-host-bridge", NULL), \
+                 TYPE_PCIE_HOST_BRIDGE)
 
 #define PCIE_HOST_MCFG_BASE "MCFG"
 #define PCIE_HOST_MCFG_SIZE "mcfg_size"
