Data Sheet

Technologies
58 Datasheet, Volume 1 of 2
Intel VT-d functionality, often referred to as an Intel VT-d Engine, has typically been
implemented at or near a PCI Express* host bridge component of a computer system.
This might be in a chipset component or in the PCI Express functionality of a processor
with integrated I/O. When one such VT-d engine receives a PCI Express transaction
from a PCI Express bus, it uses the B/D/F number associated with the transaction to
search for an Intel VT-d translation table. In doing so, it uses the B/D/F number to
traverse the data structure shown in the above figure. If it finds a valid Intel VT-d table
in this data structure, it uses that table to translate the address provided on the PCI
Express bus. If it does not find a valid translation table for a given translation, this
results in an Intel VT-d fault. If Intel VT-d translation is required, the Intel VT-d engine
performs an N-level table walk.
For more information, refer to Intel Virtualization Technology for Directed I/O
Architecture Specification http://www.intel.com/content/dam/www/public/us/en/
documents/product-specifications/vt-directed-io-spec.pdf
Intel
®
VT-d Key Features
The processor supports the following Intel VT-d features:
• Memory controller and processor graphics comply with the Intel VT-d 2.1
Specification.
• Two Intel VT-d DMA remap engines.
— iGFX DMA remap engine.
— Default DMA remap engine (covers all devices except iGFX).
• Support for root entry, context entry, and default context
• 39-bit guest physical address and host physical address widths
• Support for 4K page sizes only
• Support for register-based fault recording only (for single entry only) and support
for MSI interrupts for faults
• Support for both leaf and non-leaf caching
• Support for boot protection of default page table
• Support for non-caching of invalid page table entries
• Support for hardware based flushing of translated but pending writes and pending
reads, on IOTLB invalidation
• Support for Global, Domain specific and Page specific IOTLB invalidation
• MSI cycles (MemWr to address FEEx_xxxxh) not translated
— Translation faults result in cycle forwarding to VBIOS region (byte enables
masked for writes). Returned data may be bogus for internal agents, PEG/DMI
interfaces return unsupported request status.
• Interrupt Remapping is supported
• Queued invalidation is supported
• Intel VT-d translation bypass address range is supported (Pass Through)
The processor supports the following added new Intel VT-d features:
• 4-level Intel VT-d Page walk – both default Intel VT-d engine as well as the IGD VT-
d engine are upgraded to support 4-level Intel VT-d tables (adjusted guest address
width of 48 bits).