diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 1e07166..9af6e1e 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -787,7 +787,7 @@ static int nvme_init(PCIDevice *pci_dev)
     pci_register_bar(&n->parent_obj, 0,
         PCI_BASE_ADDRESS_SPACE_MEMORY | PCI_BASE_ADDRESS_MEM_TYPE_64,
         &n->iomem);
-    msix_init_exclusive_bar(&n->parent_obj, n->num_queues, 4);
+    msix_init_exclusive_bar(&n->parent_obj, n->num_queues, 4, true);
 
     id->vid = cpu_to_le16(pci_get_word(pci_conf + PCI_VENDOR_ID));
     id->ssvid = cpu_to_le16(pci_get_word(pci_conf + PCI_SUBSYSTEM_VENDOR_ID));
diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index 5d272c8..6ae48ae 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -631,7 +631,7 @@ static uint64_t ivshmem_get_size(IVShmemState * s) {
 
 static void ivshmem_setup_msi(IVShmemState * s)
 {
-    if (msix_init_exclusive_bar(PCI_DEVICE(s), s->vectors, 1)) {
+    if (msix_init_exclusive_bar(PCI_DEVICE(s), s->vectors, 1, true)) {
         IVSHMEM_DPRINTF("msix initialization failed\n");
         exit(1);
     }
diff --git a/hw/pci/msix.c b/hw/pci/msix.c
index 24de260..8c6d8f3 100644
--- a/hw/pci/msix.c
+++ b/hw/pci/msix.c
@@ -291,33 +291,44 @@ int msix_init(struct PCIDevice *dev, unsigned short nentries,
 }
 
 int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
-                            uint8_t bar_nr)
+                            uint8_t bar_nr, bool legacy_layout)
 {
     int ret;
     char *name;
-
-    /*
-     * Migration compatibility dictates that this remains a 4k
-     * BAR with the vector table in the lower half and PBA in
-     * the upper half.  Do not use these elsewhere!
-     */
-#define MSIX_EXCLUSIVE_BAR_SIZE 4096
-#define MSIX_EXCLUSIVE_BAR_TABLE_OFFSET 0
-#define MSIX_EXCLUSIVE_BAR_PBA_OFFSET (MSIX_EXCLUSIVE_BAR_SIZE / 2)
-#define MSIX_EXCLUSIVE_CAP_OFFSET 0
-
-    if (nentries * PCI_MSIX_ENTRY_SIZE > MSIX_EXCLUSIVE_BAR_PBA_OFFSET) {
-        return -EINVAL;
+    uint32_t bar_size;
+    uint32_t bar_pba_offset;
+
+    if (legacy_layout) {
+        /*
+         * Migration compatibility dictates that this remains a 4k
+         * BAR with the vector table in the lower half and PBA in
+         * the upper half.  Do not use these elsewhere!
+         */
+        bar_size = 4096;
+        bar_pba_offset = bar_size / 2;
+
+        if (nentries * PCI_MSIX_ENTRY_SIZE > bar_pba_offset) {
+            return -EINVAL;
+        }
+    } else {
+        bar_pba_offset = nentries * PCI_MSIX_ENTRY_SIZE;
+        bar_size = bar_pba_offset + (nentries / 8 + 1) * 8;
+        if (bar_size & (bar_size - 1)) {
+            bar_size = 1 << qemu_fls(bar_size);
+        }
+        if (bar_size < 4096) {
+            bar_size = 4096;
+        }
     }
 
     name = g_strdup_printf("%s-msix", dev->name);
-    memory_region_init(&dev->msix_exclusive_bar, OBJECT(dev), name, MSIX_EXCLUSIVE_BAR_SIZE);
+    memory_region_init(&dev->msix_exclusive_bar, OBJECT(dev), name, bar_size);
     g_free(name);
 
     ret = msix_init(dev, nentries, &dev->msix_exclusive_bar, bar_nr,
-                    MSIX_EXCLUSIVE_BAR_TABLE_OFFSET, &dev->msix_exclusive_bar,
-                    bar_nr, MSIX_EXCLUSIVE_BAR_PBA_OFFSET,
-                    MSIX_EXCLUSIVE_CAP_OFFSET);
+                    0, &dev->msix_exclusive_bar,
+                    bar_nr, bar_pba_offset,
+                    0);
     if (ret) {
         return ret;
     }
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index 02e3ce8..816a706 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -937,7 +937,7 @@ static void virtio_pci_device_plugged(DeviceState *d)
     config[PCI_INTERRUPT_PIN] = 1;
 
     if (proxy->nvectors &&
-        msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, 1)) {
+        msix_init_exclusive_bar(&proxy->pci_dev, proxy->nvectors, 1, true)) {
         error_report("unable to init msix vectors to %" PRIu32,
                      proxy->nvectors);
         proxy->nvectors = 0;
diff --git a/include/hw/pci/msix.h b/include/hw/pci/msix.h
index 954d82b..6c19535 100644
--- a/include/hw/pci/msix.h
+++ b/include/hw/pci/msix.h
@@ -11,7 +11,7 @@ int msix_init(PCIDevice *dev, unsigned short nentries,
               unsigned table_offset, MemoryRegion *pba_bar,
               uint8_t pba_bar_nr, unsigned pba_offset, uint8_t cap_pos);
 int msix_init_exclusive_bar(PCIDevice *dev, unsigned short nentries,
-                            uint8_t bar_nr);
+                            uint8_t bar_nr, bool legacy_layout);
 
 void msix_write_config(PCIDevice *dev, uint32_t address, uint32_t val, int len);
 
