Root Partition

The root partition is special in a number of ways. It is created with the following properties, capabilities, and privileges that non-root partitions do not possess:

• The root partition has no parent partition. Any of the following operations that can be performed only by a parent partition on its children cannot be performed on the root partition:
  • Changes to partition state (for example, calls to the HvInitializePartition, HvFinalizePartition, and HvDeletePartition hypercall functions)
  • Modification of partition properties (for example, calls to the HvGetPartitionProperty and HvSetPartitionProperty hypercall functions)
  • Changes to guest physical address (GPA) mappings (for example, the HvMapGpaPages hypercall function can only change access rights to an existing mapping; a call to the HvUnmapGpaPages hypercall function is not allowed.)
  • Access to guest virtual address (GVA) or GPA space (for example, calls to the HvTranslateVirtualAddress, HvReadGpa, and HvWriteGpa hypercall functions)
  • Installation of intercepts (for example, a call to the HvInstallIntercept hypercall function)
  • Virtual processor creation and deletion (for example, calls to the HvCreateVp and HvDeleteVp hypercall functions)
  • Access to virtual processor register state (for example, calls to the HvGetVpRegisters and HvSetVpRegisters hypercall functions)
  • Virtualization of legacy interrupts (for example, calls to the HvAssertVirtualInterrupt and HvClearVirtualInterrupt hypercall functions)
  • Saving and restoring partition state (for example, calls to the HvSavePartitionState and HvRestorePartitionState hypercall functions)
  • Management of logical processor states (for example, calls to the HvGetLogicalProcessorRunTime, and HvParkLogicalProcessors hypercall functions)

• The root partition, by default, can access all physical I/O ports. Other partitions cannot access any physical I/O ports. Note that some hypervisor implementations might restrict access to some I/O ports for security reasons.

• The root partition can access non-virtualized MSRs that directly control the behavior of the hardware. Note that some hypervisor implementations might restrict access to some MSRs for security reasons.

• The virtual processors within the root partition have hard affinities; that is, each virtual processor is strongly bound to a corresponding logical processor.

• By default, all mapped GPAs within the root partition's GPA space are mapped to the same addresses within the system physical address (SPA) space. This fact is not necessarily true for overlay pages.

• All hardware interrupts are directed at virtual processors within the root partition.

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Build date: 11/16/2013