> For EFI runtime service in virtual mode, using direct mapping is mainly > for kexec, where EFI runtime memory area need to be mapped at same > virtual address across kexec.
I see. I didn't consider this aspect. > - Use direct mapping of kernel, clean NX bit from kernel page table > temporarily before/after EFI calling. This needs not split 2M page into > 4K pages, because the region changed is aligned with 2M. And, because > the changing is temporary, a little larger region is not a big issue. I would just do it permanently. > Aligning > EFI runtime code region with 1G seems not a good idea too. I think a > better method is adding a non-split mode to c_p_a(), where the region > changed is enlarged if necessary to avoid page allocation. This can be > used to implement early_set_memory_xx(). The early_set_memory_xx() > instead of duplicated c_p_a() variant can be used by EFI code. I attempted something like this with my advisory vs required static protections last week, but it was rejected. But yes having such a mode would make sense agreed. The easiest way (as in least amount of code) to implement it actually is to just bypass set_memory_*() and just do the lookup_address() yourself and clear NX and do a global TLB flush. For the special case of NX that is fine because you don't need to worry about fixing up any aliases. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
