Re: [PATCH 1/3] x86/xen: Allow XEN_PV and XEN_PVH to be enabled with X86_5LEVEL

[Kirill A. Shutemov]

On Fri, Feb 16, 2018 at 06:11:10AM -0800, Matthew Wilcox wrote:
> On Fri, Feb 16, 2018 at 02:49:46PM +0300, Kirill A. Shutemov wrote:
> > @@ -38,12 +38,12 @@
> >   *
> >   */
> >  
> > +#define l4_index(x)	(((x) >> 39) & 511)
> >  #define pud_index(x)	(((x) >> PUD_SHIFT) & (PTRS_PER_PUD-1))
> 
> Shouldn't that be
> +#define p4d_index(x)	(((x) >> P4D_SHIFT) & (PTRS_PER_P4D-1))

With CONFIG_X86_5LEVEL=y, PTRS_PER_P4D is a varaible, so it won't compile.
With CONFIG_X86_5LEVEL=n, PTRS_PER_P4D is 1, so it's broken.

And I didn't want to mixin p4d here: it's actually top-level page table
in 4-level paging mode.

I guess we can do something like:

#define l4_index(x)	(((x) >> P4D_SIFT) & (PTRS_PER_PGD-1))

But to me it's more confusing than couple numbers.

-- 
 Kirill A. Shutemov