Re: [XEN v8 5/5] xen/arm: p2m: Enable support for 32bit IPA for ARM_32

[Julien Grall <julien@xxxxxxx>]

Hi Ayan,

On 02/06/2023 13:07, Ayan Kumar Halder wrote:
> Refer ARM DDI 0406C.d ID040418, B3-1345,
>
> "A stage 2 translation with an input address range of 31-34 bits can
> start the translation either:
>
> - With a first-level lookup, accessing a first-level translation
>    table with 2-16 entries.
>
> - With a second-level lookup, accessing a set of concatenated
>    second-level translation tables"
>
> Thus, for 32 bit IPA, there will be no concatenated root level tables.
> So, the root-order is 0.
>
> Also, Refer ARM DDI 0406C.d ID040418, B3-1348
> "Determining the required first lookup level for stage 2 translations
>
> For a stage 2 translation, the output address range from the stage 1
> translations determines the required input address range for the stage 2
> translation. The permitted values of VTCR.SL0 are:
> 0b00 Stage 2 translation lookup must start at the second level.
> 0b01 Stage 2 translation lookup must start at the first level.
>
> VTCR.T0SZ must indicate the required input address range. The size of
> the input address region is 2^(32-T0SZ) bytes."
>
> Thus VTCR.SL0 = 1 (maximum value) and VTCR.T0SZ = 0 when the size of
> input address region is 2^32 bytes.
>
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall