Re: [XEN][PATCH] xen/dom0less: arm: fix hwdom 1:1 low memory allocation

[dmkhn@xxxxxxxxx]

On Fri, Aug 01, 2025 at 03:54:30PM +0000, Grygorii Strashko wrote:
> From: Grygorii Strashko <grygorii_strashko@xxxxxxxx>
> 
> Call stack for dom0less hwdom case (1:1) memory:
> create_domUs
> |-construct_domU
>   |-construct_hwdom()
>     |-allocate_memory_11()
> 
> And allocate_memory_11() uses "dom0_mem" as:
> min_low_order =
>   get_order_from_bytes(min_t(paddr_t, dom0_mem, MB(128)));
> 
> In case of dom0less boot the "dom0_mem" is not used and defaulted to 0,
> which causes min_low_order to get high value > order and so no allocations
> happens from low memory.
> 
> Fix it, by using kinfo->unassigned_mem instead of "dom0_mem" has correct
> memory size in both cases: regular dom0 boot and dom0less boot.
> 
> Fixes: 43afe6f030244 ("xen/common: dom0less: introduce common 
> dom0less-build.c")
> Signed-off-by: Grygorii Strashko <grygorii_strashko@xxxxxxxx>

Reviewed-by: Denis Mukhin <dmukhin@xxxxxxxx> 

> ---
>  xen/arch/arm/domain_build.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 801a09071a50..0a555d1ae0e5 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -278,7 +278,7 @@ static void __init allocate_memory_11(struct domain *d,
>                                        struct kernel_info *kinfo)
>  {
>      const unsigned int min_low_order =
> -        get_order_from_bytes(min_t(paddr_t, dom0_mem, MB(128)));
> +        get_order_from_bytes(min_t(paddr_t, kinfo->unassigned_mem, MB(128)));
>      const unsigned int min_order = get_order_from_bytes(MB(4));
>      struct membanks *mem = kernel_info_get_mem(kinfo);
>      struct page_info *pg;
> --
> 2.34.1
>