Mitigating side-channel attacks via shared cache

A method, comprising:

• provisioning, on a virtual machine manager (VMM), a plurality of co-located virtual machines (VMs), wherein the VMM executes on a host implemented by one or more hardware processors and memory, including a main memory and a shared cache for the main memory;
• maintaining, by the VMM, for each VM of the plurality of co-located VMs, a respective memory map that maps VM memory pages to respective host memory pages in the main memory;
• determining at least a subset of current host memory pages for a selected VM that are subject to a potential occurrence of a side-channel attack, wherein each current host memory page is associated with an entry in the memory map, and the determination is based at least in part on detected collisions in the shared cache between the selected VM and another co-located VM in the subset of current host memory pages;
• relocating contents of the current host memory pages to replacement host memory pages in the main memory, wherein the relocation avoids collisions in the shared cache between the selected VM and the other co-located VM for the subset of current host memory pages to hinder the potential occurrence of the side-channel attack;
• and
• modifying the associated entries in the memory map to change current host memory pages in to the replacement host memory pages.

A non-transitory computer-accessible storage medium storing program instructions that when executed on one or more processors cause the one or more processors to:

• provision, on a virtual machine manager (VMM), a plurality of co-located virtual machines (VMs), wherein the VMM executes on a host implemented by one or more hardware processors and memory, including a main memory and a shared cache for the main memory;
• maintain, by the VMM, for each VM of the plurality of co-located VMs, a respective memory map that maps VM memory pages to respective host memory pages in the main memory;
• determine at least a subset of current host memory pages for a selected VM that are subject to a potential occurrence of a side-channel attack, wherein each current host memory page is associated with an entry in the memory map, and the determination is based at least in part on detected collisions in the shared cache between the selected VM and another co-located VM for the subset of current host memory pages;
• relocate contents of the current host memory pages to replacement host memory pages in the main memory, wherein the relocation avoids collisions in the shared cache between the selected VM and the other co-located VM for the subset of current host memory pages to hinder the potential occurrence of the side-channel attack;
• and
• modify the associated entries in the memory map to change the current host memory pages to the respective replacement host memory pages.