KVM in Linux Kernel 2.6.28 features Intel VT-d support, soon nested virtualization

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The just released Kernel 2.6.28 includes more than 104 patches for the virtualization engine KVM, included in Linux since 2.6.20.

One of those patches is specially important as it allows the mapping of physical PCI device to a specific virtual machine through the Intel Virtualization for Directed I/O (VT-d) technology.

Intel introduced VT-d in early Q1 2006 but so far only Novell and Oracle supported it in their Xen implementations (as the virtualization.info Buyer’s Guide highlights).

The PCI direct access grants higher performance but lower flexibility in a virtual infrastructure: for instance a VM can only map as many devices as are physically present in the platform.
Nonetheless it’s a critical step to bring high-performance virtualization on consumer equipment (something often called client hypervisor) like laptops.

Red Hat, which is the main contributor of KVM after the acquisition of Qumranet, has all the interest to achieve the goal as the company executives clarified last month.

Meanwhile KVM continues to get new features: in its last build, KVM-82, the platform allows users to nested virtual machines when running on AMD CPUs.