The VirtIO PCI configuration access capability creates an alternative access method to the common configuration, notifications, ISR, and device-specific configuration structure regions. This interface provides a means for the driver to access the VirtIO device region of Physical Functions (PFs) or Virtual Functions (VFs).
VirtIO is an industry standard for software-based virtualization that is supported natively by Linux. In VirtIO, software implements the virtualization stack, whereas in the case of SR-IOV, this stack is implemented mostly in hardware.
Below is the block diagram of the Soft IP which implements the VirtIO capability for PFs and VFs. This Soft IP block is automatically included when the VirtIO feature is enabled in the IP Parameter Editor.