Re: [PATCH v10 12/12] xen/arm: add cache coloring support for Xen

[Jan Beulich <jbeulich@xxxxxxxx>]

On 19.11.2024 15:13, Carlo Nonato wrote:
> Add the cache coloring support for Xen physical space.
> 
> Since Xen must be relocated to a new physical space, some relocation
> functionalities must be brought back:
> - the virtual address of the new space is taken from 0c18fb76323b
>   ("xen/arm: Remove unused BOOT_RELOC_VIRT_START").
> - relocate_xen() and get_xen_paddr() are taken from f60658c6ae47
>   ("xen/arm: Stop relocating Xen").
> 
> setup_pagetables() must be adapted for coloring and for relocation. Runtime
> page tables are used to map the colored space, but they are also linked in
> boot tables so that the new space is temporarily available for relocation.
> This implies that Xen protection must happen after the copy.
> 
> Finally, since the alternative framework needs to remap the Xen text and
> inittext sections, this operation must be done in a coloring-aware way.
> The function xen_remap_colored() is introduced for that.
> 
> Signed-off-by: Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
> Signed-off-by: Marco Solieri <marco.solieri@xxxxxxxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> # common
preferably with ...

> @@ -353,6 +355,22 @@ unsigned int get_max_nr_llc_colors(void)
>      return max_nr_colors;
>  }
>  
> +mfn_t __init xen_colored_mfn(mfn_t mfn)
> +{
> +    unsigned int i, color = mfn_to_color(mfn);
> +
> +    for ( i = 0; i < xen_num_colors; i++ )
> +    {
> +        if ( color == xen_colors[i] )
> +            return mfn;
> +        else if ( color < xen_colors[i] )

... "else" dropped from here.

Jan