HvCallEnableVpVtl enables a VTL to run on a VP. This hypercall should be used in conjunction with HvCallEnablePartitionVtl to enable and use a VTL. To enable a VTL on a VP, it must first be enabled for the partition. This call does not change the active VTL.


   _In_ HV_PARTITION_ID TargetPartitionId,
   _In_ HV_VP_INDEX VpIndex,
   _In_ HV_VTL TargetVtl,


In general, a VTL can only be enabled by a higher VTL. There is one exception to this rule: the highest VTL enabled for a partition can enable a higher target VTL.

Once the target VTL is enabled on a VP, all other calls to enable the VTL must come from equal or greater VTLs. This hypercall will fail if called to enable a VTL that is already enabled for a VP.

Call Code

0x000F (Simple)

Input Parameters

Name Offset Size Information Provided
TargetPartitionId 0 8 Supplies the partition ID of the partition this request is for.
VpIndex 8 4 Specifies the index of the virtual processor on which to enable the VTL.
TargetVtl 12 1 Specifies the VTL to be enabled by this hypercall.
RsvdZ 13 3
VpVtlContext 16 224 Specifies the initial context in which the VP should start upon the first entry to the target VTL.

See also