intel vt-d for hvm

[Tommy_F_]

Hello

can someone explain why intel vt-d is required for HVM ( fully virtualized VM) and not for Para-virtualized VMs.

I know that in the pci-passthrough, the VM has control of the PCI. so the PCI needs to do DMA access to the VM memory, but as this is not possible, the PCI will tell the IOMMU about the virtual address, which will be converted to the physcial address in RAM, which corresponds to the VM memory.

But what happens in case of Para-virtualization VM?

[Quoc-Thai_L_Intel]

See the article "Best Practices for Paravirtualization Enhancements from Intel® Virtualization Technology: EPT and VT-d" for the explaination to your question.

-Thai