Hot-plug of devices in virtualized computer systems

A host computer system comprising:

• a hardware bus;
• and
• a processing device, operatively coupled to the hardware bus to:
• determine, by a hypervisor, a first set of address ranges of a resource that are allocated for one or more virtual devices attached to at least one of a plurality of virtual buses of a virtual machine;
• determine by the hypervisor, in view of the first set of address ranges, a second set of address ranges of the resource available for attaching one or more additional virtual devices to at least one of the plurality of virtual buses;
• and
• assign to the plurality of virtual buses, by the hypervisor, non-overlapping respective address ranges of the resource that are within the second set of address ranges.

A non-transitory computer-readable storage medium comprising instructions that when executed by a processing device of a host computer system, cause the processing device to execute a hypervisor to:

• obtain, by the processing device executing the hypervisor of the host computer system, a value representing a quantity of a resource for a virtual root bus of a virtual machine (VM);
• allocate, by the hypervisor, a first address range of the resource for one or more virtual devices attached to the virtual root bus, wherein the first address range is allocated in view of the value;
• determine by the hypervisor, in view of the first address range, a second address range of the resource available for attaching one or more additional virtual devices to the virtual root bus;
• and
• assign to the virtual root bus, by the hypervisor, one or more address ranges of the resource that are within the second address range.