--- a/tools/qemu-xen-traditional/hw/pass-through.c	2016-11-29 17:36:38.000000000 +0100
+++ b/tools/qemu-xen-traditional/hw/pass-through.c	2017-04-06 18:45:34.545980614 +0200
@@ -692,7 +692,7 @@ static struct pt_reg_info_tbl pt_emu_reg
         .init_val   = 0x0000,
         .res_mask   = 0xFE00,
         .ro_mask    = 0x018E,
-        .emu_mask   = 0x017E,
+        .emu_mask   = 0x017F,
         .init       = pt_msgctrl_reg_init,
         .u.w.read   = pt_word_reg_read,
         .u.w.write  = pt_msgctrl_reg_write,
@@ -3589,16 +3589,16 @@ static int pt_cmd_reg_write(struct pt_de
     /* create value for writing to I/O device register */
     if (*value & PCI_COMMAND_DISABLE_INTx)
     {
-        if (ptdev->msi_trans_en)
+        /*if (ptdev->msi_trans_en)
             msi_set_enable(ptdev, 0);
-        else
+        else*/
             throughable_mask |= PCI_COMMAND_DISABLE_INTx;
     }
     else
     {
-        if (ptdev->msi_trans_en)
+        /*if (ptdev->msi_trans_en)
             msi_set_enable(ptdev, 1);
-        else
+        else*/
             if (ptdev->machine_irq)
                 throughable_mask |= PCI_COMMAND_DISABLE_INTx;
     }
@@ -3968,10 +3968,12 @@ static int pt_msgctrl_reg_write(struct p
     /* modify emulate register */
     writable_mask = reg->emu_mask & ~reg->ro_mask & valid_mask;
     /* also emulate MSI_ENABLE bit for MSI-INTx translation */
+/*
     if (ptdev->msi_trans_en) {
         writable_mask |= PCI_MSI_FLAGS_ENABLE & valid_mask;
         throughable_mask &= ~PCI_MSI_FLAGS_ENABLE;
     }
+*/
     cfg_entry->data = PT_MERGE_VALUE(*value, cfg_entry->data, writable_mask);
     /* update the msi_info too */
     ptdev->msi->flags |= cfg_entry->data &
@@ -3987,10 +3989,10 @@ static int pt_msgctrl_reg_write(struct p
         /* setup MSI pirq for the first time */
         if (ptdev->msi->flags & MSI_FLAG_UNINIT)
         {
-            if (ptdev->msi_trans_en) {
+/*            if (ptdev->msi_trans_en) {
                 PT_LOG("guest enabling MSI, disable MSI-INTx translation\n");
                 pt_disable_msi_translate(ptdev);
-            }
+            } */
             /* Init physical one */
             PT_LOG("setup msi for dev %x\n", pd->devfn);
             if (pt_msi_setup(ptdev))
@@ -4022,6 +4024,12 @@ static int pt_msgctrl_reg_write(struct p
         }
     }
 
+     /* pass through MSI_ENABLE bit when no MSI-INTx translation */
+     if (!ptdev->msi_trans_en) {
+         *value &= ~PCI_MSI_FLAGS_ENABLE;
+         *value |= val & PCI_MSI_FLAGS_ENABLE;
+     }
+
     return 0;
 }
 
@@ -4149,10 +4157,10 @@ static int pt_msixctrl_reg_write(struct
     /* update MSI-X */
     if ((*value & PCI_MSIX_ENABLE) && !(*value & PCI_MSIX_MASK))
     {
-        if (ptdev->msi_trans_en) {
+/*        if (ptdev->msi_trans_en) {
             PT_LOG("guest enabling MSI-X, disable MSI-INTx translation\n");
             pt_disable_msi_translate(ptdev);
-        }
+        }*/
         pt_msix_update(ptdev);
     } else if (!(*value & PCI_MSIX_ENABLE) && ptdev->msix->enabled) {
         pt_msix_disable(ptdev);