Re: [XEN v2 11/11] xen/arm: p2m: Enable support for 32bit IPA

[Julien Grall <julien@xxxxxxx>]

Hi Ayan,

On 17/01/2023 17:43, Ayan Kumar Halder wrote:
> VTCR.T0SZ should be set as 0x20 to support 32bit IPA.
> Refer ARM DDI 0487I.a ID081822, G8-9824, G8.2.171, VTCR,
> "Virtualization Translation Control Register" for the bit descriptions.
>
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
> ---
> Changes from -
>
> v1 - New patch.
>
>   xen/arch/arm/p2m.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 948f199d84..cfdea55e71 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -2266,13 +2266,17 @@ void __init setup_virt_paging(void)
>       register_t val = VTCR_RES1|VTCR_SH0_IS|VTCR_ORGN0_WBWA|VTCR_IRGN0_WBWA;
>   
>   #ifdef CONFIG_ARM_32
> -    if ( p2m_ipa_bits < 40 )
> +    if ( p2m_ipa_bits < PADDR_BITS )
>           panic("P2M: Not able to support %u-bit IPA at the moment\n",
>                 p2m_ipa_bits);
>   
> -    printk("P2M: 40-bit IPA\n");
> -    p2m_ipa_bits = 40;
> +    printk("P2M: %u-bit IPA\n",PADDR_BITS);
> +    p2m_ipa_bits = PADDR_BITS;
> +#ifdef CONFIG_ARM_PA_32
> +    val |= VTCR_T0SZ(0x20); /* 32 bit IPA */
> +#else
>       val |= VTCR_T0SZ(0x18); /* 40 bit IPA */
> +#endif
I am wondering whether this is right time to switch to an array like the 
arm64 code? This would allow to use 32-bit IPA also when Xen support 
64-bit physical address.
Cheers,

--
Julien Grall