Re: [PATCH 2/3] x86/mm: introduce __PAGE_KERNEL_GLOBAL

[Nadav Amit]

Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> wrote:

> 
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> 
> Kernel mappings are historically _PAGE_GLOBAL.  But, with PTI, we do not
> want them to be _PAGE_GLOBAL.  We currently accomplish this by simply
> clearing _PAGE_GLOBAL from the suppotred mask which ensures it is
> cleansed from many of our PTE construction sites:
> 
>        if (!static_cpu_has(X86_FEATURE_PTI))
> 	                __supported_pte_mask |= _PAGE_GLOBAL;
> 
> But, this also means that we now get *no* opportunity to use global
> pages with PTI, even for data which is shared such as the cpu_entry_area
> and entry/exit text.


Doesnât this patch change the kernel behavior when the ânoptiâ parameter is used?