diff --git a/hw/pass-through.c b/hw/pass-through.c
index 8d80755..b1a3b09 100644
--- a/hw/pass-through.c
+++ b/hw/pass-through.c
@@ -626,6 +626,7 @@ static struct pt_reg_info_tbl pt_emu_reg_msi_tbl[] = {
         .init_val   = 0x00000000,
         .ro_mask    = 0x00000003,
         .emu_mask   = 0xFFFFFFFF,
+        .no_wb      = 1,
         .init       = pt_common_reg_init,
         .u.dw.read  = pt_long_reg_read,
         .u.dw.write = pt_msgaddr32_reg_write,
@@ -638,6 +639,7 @@ static struct pt_reg_info_tbl pt_emu_reg_msi_tbl[] = {
         .init_val   = 0x00000000,
         .ro_mask    = 0x00000000,
         .emu_mask   = 0xFFFFFFFF,
+        .no_wb      = 1,
         .init       = pt_msgaddr64_reg_init,
         .u.dw.read  = pt_long_reg_read,
         .u.dw.write = pt_msgaddr64_reg_write,
@@ -650,6 +652,7 @@ static struct pt_reg_info_tbl pt_emu_reg_msi_tbl[] = {
         .init_val   = 0x0000,
         .ro_mask    = 0x0000,
         .emu_mask   = 0xFFFF,
+        .no_wb      = 1,
         .init       = pt_msgdata_reg_init,
         .u.w.read   = pt_word_reg_read,
         .u.w.write  = pt_msgdata_reg_write,
@@ -662,6 +665,7 @@ static struct pt_reg_info_tbl pt_emu_reg_msi_tbl[] = {
         .init_val   = 0x0000,
         .ro_mask    = 0x0000,
         .emu_mask   = 0xFFFF,
+        .no_wb      = 1,
         .init       = pt_msgdata_reg_init,
         .u.w.read   = pt_word_reg_read,
         .u.w.write  = pt_msgdata_reg_write,
@@ -1550,10 +1554,12 @@ static void pt_pci_write_config(PCIDevice *d, uint32_t address, uint32_t val,
     val >>= ((address & 3) << 3);
 
 out:
-    ret = pci_write_block(pci_dev, address, (uint8_t *)&val, len);
+    if (!reg->no_wb) {
+        ret = pci_write_block(pci_dev, address, (uint8_t *)&val, len);
 
-    if (!ret)
-        PT_LOG("Error: pci_write_block failed. return value[%d].\n", ret);
+        if (!ret)
+            PT_LOG("Error: pci_write_block failed. return value[%d].\n", ret);
+    }
 
     if (pm_state != NULL && pm_state->flags & PT_FLAG_TRANSITING)
         /* set QEMUTimer */
diff --git a/hw/pass-through.h b/hw/pass-through.h
index 028a03e..3c79885 100644
--- a/hw/pass-through.h
+++ b/hw/pass-through.h
@@ -364,6 +364,8 @@ struct pt_reg_info_tbl {
     uint32_t ro_mask;
     /* reg emulate field mask (ON:emu, OFF:passthrough) */
     uint32_t emu_mask;
+    /* no write back allowed */
+    uint32_t no_wb;
     /* emul reg initialize method */
     conf_reg_init init;
     union {