Re: [PATCH for-4.15] x86/mem_sharing: copy parent VM's hostp2m's max_mapped_pfn during forking

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.03.2021 22:36, Tamas K Lengyel wrote:
> --- a/xen/arch/x86/mm/mem_sharing.c
> +++ b/xen/arch/x86/mm/mem_sharing.c
> @@ -1761,6 +1761,7 @@ static int copy_settings(struct domain *cd, struct 
> domain *d)
>          return rc;
>  
>      copy_tsc(cd, d);
> +    p2m_get_hostp2m(cd)->max_mapped_pfn = p2m_get_hostp2m(d)->max_mapped_pfn;

Makes sense to me, yes, but then an immediate question is: What
about the somewhat similar {min,max}_remapped_gfn fields? Which
of course implies the more general question of how alternate
p2m-s (are supposed to) get treated in the first place. From my
looking at it, fork() doesn't appear to also fork those, but
also doesn't appear to refuse cloning when altp2m is in use.

Jan