Re: [PATCH v7 2/7] tools/xl: Add altp2m_count parameter

[Anthony PERARD <anthony@xenproject.org>]

On Tue, Jul 01, 2025 at 07:54:24PM +0000, Petr Beneš wrote:
> diff --git a/tools/libs/light/libxl_create.c b/tools/libs/light/libxl_create.c
> index 8a85fba1cf..acf7fd9837 100644
> --- a/tools/libs/light/libxl_create.c
> +++ b/tools/libs/light/libxl_create.c
> @@ -421,6 +421,15 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
>          return -ERROR_INVAL;
>      }
>  
> +    if (b_info->altp2m_count == LIBXL_ALTP2M_COUNT_DEFAULT) {
> +        if ((libxl_defbool_val(b_info->u.hvm.altp2m) ||

This access turned out to be an issue. "hvm.altp2m" is only set to a
default value for hvm guests on x86, in
libxl__arch_domain_build_info_setdefault() in ibxl_x86.c. So trying to
create a PV guest will fail here.

It seems that altp2m_count is going to be used for the creation of all
guest, right? That is in addition to HVM, it will be also used for PV
guest and on Arm, and any other architectures that could be added. What
should be the value of altp2m_count in all this case, if altp2m is only
set on x86 HVM guest?


> +            b_info->altp2m != LIBXL_ALTP2M_MODE_DISABLED))
> +            /* Reflect the default legacy count */
> +            b_info->altp2m_count = 10;
> +        else
> +            b_info->altp2m_count = 0;

Cheers,

-- 
Anthony PERARD