Re: [Xen-devel] [PATCH MM-PART2 RESEND v2 13/19] xen/arm32: mm: Avoid to zero and clean cache for CPU0 domheap

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 14 May 2019, Julien Grall wrote:
> The page-table walker is configured to use the same shareability and
> cacheability as the access performed when updating the page-tables. This
> means cleaning the cache for CPU0 domheap is unnecessary.
> 
> Furthermore, CPU0 page-tables are part of Xen binary and will already be
> zeroed before been used. So it is pointless to zero the domheap again.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Reviewed-by: Andrii Anisov <andrii_anisov@xxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>     Changes in v2:
>         - Tweak a bit the commit message
>         - Add Andrii's reviewed-by
> ---
>  xen/arch/arm/mm.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index e090afb976..cda2847d00 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -724,11 +724,6 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset)
>  #ifdef CONFIG_ARM_32
>      per_cpu(xen_pgtable, 0) = cpu0_pgtable;
>      per_cpu(xen_dommap, 0) = cpu0_dommap;
> -
> -    /* Make sure it is clear */
> -    memset(this_cpu(xen_dommap), 0, DOMHEAP_SECOND_PAGES*PAGE_SIZE);
> -    clean_dcache_va_range(this_cpu(xen_dommap),
> -                              DOMHEAP_SECOND_PAGES*PAGE_SIZE);
>  #endif
>  }
>  
> -- 
> 2.11.0
> 

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