Re: [PATCH v3 02/18] x86/mm: purge unneeded destroy_perdomain_mapping()

[Jan Beulich <jbeulich@suse.com>]

On 07.10.2026 12:40, George Dunlap wrote:
> --- a/xen/arch/x86/x86_64/mm.c
> +++ b/xen/arch/x86/x86_64/mm.c
> @@ -737,6 +737,11 @@ int setup_compat_arg_xlat(struct vcpu *v)
>                                      NULL, NIL(struct page_info *));
>  }
>  
> +/*
> + * Besides vCPU teardown, which free_perdomain_mappings() would cover, this
> + * serves switch_compat()'s undo path: the domain lives on as a 64-bit one
> + * there, so the translation area has to go right away.
> + */

Is it really "has to"? The xlat area is simply unused for 64-bit guests,
so it would be merely "needlessly occupying resources" if we deferred
freeing until domain destruction. Preferably with a respective adjustment
(and perhaps also the adjustment suggested by Roger):
Reviewed-by: Jan Beulich <jbeulich@suse.com>

Jan