Re: [Xen-devel] [For Xen-4.10 RFC PATCH 2/3] arm: p2m: Prevent redundant icache flushes

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 31 Mar 2017, Punit Agrawal wrote:
> When toolstack requests flushing the caches, flush_page_to_ram() is
> called for each page of the requested domain. This needs to unnecessary
> icache invalidation operations.
> 
> Let's take the responsibility of performing icache operations and use
> the recently introduced flag to prevent redundant icache operations by
> flush_page_to_ram().
> 
> Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/arm/p2m.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 76cd1c34f3..8136522ed8 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -1400,13 +1400,15 @@ int p2m_cache_flush(struct domain *d, gfn_t start, 
> unsigned long nr)
>          /* XXX: Implement preemption */
>          while ( gfn_x(start) < gfn_x(next_gfn) )
>          {
> -            flush_page_to_ram(mfn_x(mfn), true);
> +            flush_page_to_ram(mfn_x(mfn), false);
>  
>              start = gfn_add(start, 1);
>              mfn = mfn_add(mfn, 1);
>          }
>      }
>  
> +    invalidate_icache();
> +
>      p2m_read_unlock(p2m);
>  
>      return 0;
> -- 
> 2.11.0
> 

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