--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -278,7 +278,7 @@ static struct pci_dev *alloc_pdev(struct
     INIT_LIST_HEAD(&pdev->msi_list);
 
     if ( pci_find_cap_offset(pseg->nr, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
-                             PCI_CAP_ID_MSIX) )
+                             PCI_CAP_ID_MSIX | 0x80) )
     {
         struct arch_msix *msix = xzalloc(struct arch_msix);
 
--- a/xen/drivers/pci/pci.c
+++ b/xen/drivers/pci/pci.c
@@ -14,19 +14,24 @@ int pci_find_cap_offset(u16 seg, u8 bus,
     int max_cap = 48;
     u8 pos = PCI_CAPABILITY_LIST;
     u16 status;
+bool_t log = (cap & 0x80) && !seg && bus == 2;//temp
+cap &= ~0x80;//temp
 
     status = pci_conf_read16(seg, bus, dev, func, PCI_STATUS);
+if(log) printk("02:%02x.%u: status=%04x (%ps wants %02x)\n", dev, func, status, __builtin_return_address(0), cap);//temp
     if ( (status & PCI_STATUS_CAP_LIST) == 0 )
         return 0;
 
     while ( max_cap-- )
     {
         pos = pci_conf_read8(seg, bus, dev, func, pos);
+if(log) printk("02:%02x.%u: pos=%02x\n", dev, func, pos);//temp
         if ( pos < 0x40 )
             break;
 
         pos &= ~3;
         id = pci_conf_read8(seg, bus, dev, func, pos + PCI_CAP_LIST_ID);
+if(log) printk("02:%02x.%u: id=%02x\n", dev, func, id);//temp
 
         if ( id == 0xff )
             break;
@@ -35,6 +40,7 @@ int pci_find_cap_offset(u16 seg, u8 bus,
 
         pos += PCI_CAP_LIST_NEXT;
     }
+if(log) printk("02:%02x.%u: no cap %02x\n", dev, func, cap);//temp
 
     return 0;
 }