KVM_HOST_PTE_OWNER_GUEST_GFN_MASK
WARN_ON(!FIELD_FIT(KVM_HOST_PTE_OWNER_GUEST_GFN_MASK, gfn));
FIELD_PREP(KVM_HOST_PTE_OWNER_GUEST_GFN_MASK, gfn);
*gfn = FIELD_GET(KVM_HOST_PTE_OWNER_GUEST_GFN_MASK, meta);