A method and system for machine memory power and availability management in a processing system supporting multiple virtual machines provides a mechanism for supporting memory power management and memory failure management in large scale systems. Upon a decision to take a memory module off-line or place the module in an increased-latency state for power management, or upon a notification that a memory module has failed or been taken off-line or has had latency increased by another power management control mechanism, a hypervisor that supports multiple virtual machines checks the use of pages by each virtual machine and its guest operating system by using a reverse mapping. The hypervisor determines which virtual machines are using a particular machine memory page and may re-map the machine memory page to another available machine page, or may notify the virtual machines that the memory page has become or is becoming unavailable via a fault or other notification mechanism. Alternatively, or in the absence of a response from a virtual machine, the hypervisor can shut down the affected partition(s).