Hi,

I have been using xen hypervisor and tianocore uefi BIOS on xen to boot to ubuntu OS on virtualized disk.

and want to set a UEFI variable with UEFI runtime service SetVariable() to a value and the same wants to read from UEFI bootloader either grubx64.efi or botmgfw.efi,

So, Is it possible to use runtime services to do such an operation for OS running on VM when booted with OVMF/tianocore BIOS on VM guest? 

If so, where does this variable gets stored? is it in some virtualized disk as there is no virtualized SPIROM available to VM.