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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 18.06.2026 14:13, Andrew Cooper wrote:
> 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.

Aiui it's a regression vs 4.20, i.e. will want backporting to 4.21.

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

Thanks.

>> --- 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.

I have a far more consolidating patch in the works, which is how I actually
noticed the issue. I'd prefer to keep things as simple as possible here.

Jan