Re: [PATCH for-4.22] XSM: guard .sysctl() and .readconsole() hooks

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 18/06/2026 12:32 pm, Jan Beulich wrote:
> Leaving the hook pointers in struct xsm_ops when !SYSCTL would lead to
> the BUG_ON() in xsm_fixup_ops() triggering for respectively configured
> hypervisors.
>
> While moving the #ifdef for the corresponding xsm_*() wrappers, also move
> those for xsm_page_offline() (where the hook pointer field already is
> suitably guarded).
>
> Fixes: c9eabaa03a68 ("xen/xsm: wrap around xsm_sysctl with CONFIG_SYSCTL")
> Fixes: bddd9af6049f ("xen/sysctl: wrap around XEN_SYSCTL_readconsole")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Ugly.  We probably ought to see about booting the RANDCONFIG hypervisor
too, which should be able to spot things like this.

This is a regression vs 4.21, so does need including.

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, although...

>
> --- a/xen/include/xsm/xsm.h
> +++ b/xen/include/xsm/xsm.h
> @@ -61,8 +61,10 @@ struct xsm_ops {
>  #endif
>      int (*set_target)(struct domain *d, struct domain *e);
>      int (*domctl)(struct domain *d, struct xen_domctl *op);
> +#ifdef CONFIG_SYSCTL
>      int (*sysctl)(int cmd);
>      int (*readconsole)(uint32_t clear);
> +#endif

... this is now the 3rd CONFIG_SYSCTL in xsm_ops.

I know it will grow the diff, but can we see about collecting them into
a single region, and in dummy_ops too?  It will shrink the overall
result, and the order of pointers in this ops structure is uninteresting.

~Andrew