Trouble understanding how `inject_trap_pa` works. about drakvuf

[tklengyel]

The shadow page where the traps are also part of the guest memory at a magic offset. The magic offset while not advertised via e820/efi memory map would still be accessible by a guest that knows where to look. So the guard2 rwx trap is to protect the shadow page from being accessed via the magic offset and keep it only accessible through the remapped gfn.

[archercreat]

Thank you, Tamas! I now understand that the original page under current gfn will be swapped with remapped one. So the r/w trap is actually placed on remapped page.