Yes, it is. However, for VMware products as guest hypervisors, we expect it to provide little to no benefit. We already avoid many VM-exits due to VMREAD/VMWRITE by clustering these operations together (https://labs.vmware.com/academic/publications/software-techniques). For other guest hypervisors that don't arrange their VMREAD/VMWRITE operations to be virtualization-friendly, VMCS shadowing should provide some benefit. The benefits will vary depending on the number of VMREAD/VMWRITE operations per nested VM-exit. A guest hypervisor like Hyper-V, which performs very few VMREAD/VMWRITE operations per VM-exit, will see little benefit. A guest hypervisor like VirtualBox, which performs quite a few VMREAD/VMWRITE operations per VM-exit, will see a greater benefit.
