Which aspect of a virtual machine can be assigned a "reservation" in CPU QoS settings?

The concept of "reservation" in CPU Quality of Service (QoS) settings pertains to ensuring that a virtual machine (VM) has a guaranteed minimum amount of CPU resources available for its operation. This is crucial in environments where multiple VMs are competing for limited CPU resources, as it prevents any single VM from starving for necessary processing power to perform its tasks effectively.

When a reservation is set, it establishes a baseline performance level, ensuring that the designated CPU resources will always be allocated to the virtual machine, regardless of the load on the overall host system. This guarantees that the VM can function properly even under high load conditions where other VMs might be consuming excessive CPU resources.

The other aspects mentioned—maximum host limit, operational permissions, and resource sharing priority—do not involve a guaranteed allocation of resources. The maximum host limit caps the resources a VM can utilize but doesn't ensure a minimum allocation, operational permissions relate to access and control rather than resource allocation, and resource sharing priority dictates how resources are shared amongst VMs rather than providing a specific guarantee of availability. Thus, the correct answer is indeed the minimum resource guarantee, as it is the aspect directly tied to the concept of reservation in CPU QoS settings.