Oracle VM 3.3.1 server dmesg might occasionally shows "pci_mag_sg failed" error messages. These are caused by the limited capacity of the software IO TLB.
Affected software:
Oracle VM Server 3.3.1
Releases 1.0 and later
Workaround:
Set the swiotlb=65762 in kernel parameters to enlarge it to 128M. If the issue remains, enlarge the value to 131524 or 263048.