On 22.08.2024 12:52, Ayan Kumar Halder wrote: > I will update the commit message as below. Let me know if this makes > sense.
Certainly better. One more question though: > ``` > xen: make VMAP support in MMU system only > > Introduce CONFIG_HAS_VMAP which is selected by the architectures that > use MMU. vm_init() does not do anything if CONFIG_HAS_VMAP is not > enabled. > > HAS_VMAP is widely used in ALTERNATIVE feature to remap a range of > memory with new memory attributes. Since this is highly dependent on > virtual address translation, we choose to fold HAS_VMAP in MMU. And > ALTERNATIVE depends on HAS_VMAP. What is "fold HAS_VMAP in MMU"? I see no folding anywhere. My only guess is that this means to describe the "select HAS_VMAP" being added to MMU. But then why the word "fold"? Jan > At the moment, the users of HARDEN_BRANCH_PREDICTOR requires to use the > vmap() to update the exceptions vectors. While it might be possible to > rework the code, it is believed that speculative attackes would be > difficult to exploit on non-MMU because the software is tightly > controlled. So for now make HARDEN_BRANCH_PREDICTOR to depend on the > MMU. > > Also took the opportunity to remove "#ifdef VMAP_VIRT_START .. endif" > from vmap.c. Instead vmap.c is compiled when HAS_VMAP is enabled. Thus, > HAS_VMAP is now enabled from x86, ppc and riscv architectures as all of > them use MMU and has VMAP_VIRT_START defined. > > ``` > > - Ayan > >> >> Acked-by: Julien Grall <[email protected]> >> >> Cheers, >>
