Re: [Minios-devel] [UNIKRAFT PATCHv3 20/25] plat/kvm: arm64: Build L3 page table for range greater than 2MB

[Sharan Santhanam <sharan.santhanam@xxxxxxxxx>]

Hello Wei Chen,

Please find the comment inline

Thanks & Regards
Sharan

On 12/13/18 10:15 AM, Wei Chen wrote:
> Current L3 table build function only supports to build L3 table for
> memory range not exceeded than 2MB. But as we mentioned in previous
> patch, the image size will be greater than 2MB. So in this case, build
> L3 table for bigger image is not convenient. We have improve the
> function of building L3 table to support bigger memory range.
>
> Signed-off-by: Wei Chen <wei.chen@xxxxxxx>
> ---
>   plat/kvm/arm/pagetable64.S | 19 ++++++++++++++++---
>   1 file changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/plat/kvm/arm/pagetable64.S b/plat/kvm/arm/pagetable64.S
> index bd473bf..212f8e0 100644
> --- a/plat/kvm/arm/pagetable64.S
> +++ b/plat/kvm/arm/pagetable64.S
> @@ -427,7 +427,13 @@ link_l2_pagetable:
>    *  x11, x12 and x13 are trashed
>    */
>   build_l3_pagetable:
> -       /* Find the table index */
> +       /* Find the first L3 table to be updated */
> +       lsr x11, x8, #L2_SHIFT
> +       and x11, x11, #Ln_ADDR_MASK
> +       lsl x11, x11, #L3_SHIFT
Why are we shifting right by L2_SHIFT and left with L3_SHIFT? Shouldn't 
it be L3_SHIFT in both cases?

> +       add x6, x11, x6
> +
> +       /* Find the first entry index in L3 table */
>         lsr x11, x8, #L3_SHIFT
>         and x11, x11, #Ln_ADDR_MASK
>   
> @@ -446,10 +452,17 @@ build_l3_pagetable:
>   
>   	/* Store the entry */
>         str x13, [x6, x11, lsl #3]
> +       add x11, x11, #1
>   
> +	/* Cross L3 Page? */
> +       and x11, x11, #Ln_ADDR_MASK
> +       cbnz x11, 2f
> +
> +       /* To next L3 table */
> +       add x6, x6, #__PAGE_SIZE
> +
> +2:     add x9, x9, #1
>         sub x10, x10, #1
> -       add x11, x11, #1
> -       add x9, x9, #1
>         cbnz x10, 1b
>   
>   	ret
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