VT-d (Virtualization Technology for Directed I/O) is a feature introduced by Intel in 2006 as part of its Intel Virtualization Technology suite. VT-d enhances system virtualization by providing hardware support for managing and isolating direct memory access (DMA) from peripheral devices to ensure better security and performance in virtualized environments. It enables the direct assignment of physical I/O devices, such as GPUs or network interface cards (NICs), to virtual machines (VMs), bypassing the hypervisor for efficient data transfers.
https://en.wikipedia.org/wiki/X86_virtualization#VT-d
The primary benefit of VT-d is its ability to provide device isolation and prevent unauthorized memory access from peripheral devices. This protection is particularly critical for enterprise environments where multiple virtual machines share the same physical hardware. VT-d achieves this by remapping device memory access requests to the appropriate virtual machine’s address space, ensuring secure and efficient use of system resources. These capabilities also reduce latency and improve throughput, making VT-d essential for tasks like high-performance computing and data center operations.
VT-d has been widely adopted in technologies like Thunderbolt 4 to ensure secure connectivity in modern devices. By leveraging VT-d's DMA remapping features, Thunderbolt 4 can prevent malicious peripherals from accessing system memory, enhancing security in consumer and enterprise systems. The integration of VT-d into virtualization platforms like VMware ESXi and Microsoft Hyper-V has further established its importance in delivering secure, efficient, and reliable virtualization solutions.