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Tue, 17 Sep 2024 15:08:52 +0000 Message-ID: <7467f313-761a-42ed-ae2d-cdadfd93db90@intel.com> Date: Tue, 17 Sep 2024 08:08:50 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] x86/resctrl: Avoid overflow in MB settings in bw_validate() To: Martin Kletzander CC: Fenghua Yu , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , , "H. 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>>>       } >>> >>> -    if ((bw < r->membw.min_bw || bw > r->default_ctrl) && >>> -        !is_mba_sc(r)) { >>> +    /* Nothing else to do if software controller is enabled */ >>> +    if (is_mba_sc(r)) { >>> +        *data = bw; >>> +        return true; >> >> While this would fix the scenario tested I do not believe this fully addresses the >> overflow issue. As I understand the test wrote U32_MAX to the schemata file, >> which triggered the overflow because of the rounding and is fixed by this patch. Looks like, >> after this patch, writing "U32_MAX + 1" will still trigger the overflow. >> >> The overflow appears to result from some inconsistent type use and not using >> appropriate parsing API that is able to detect overflow. >> >> How about something like below: >> > > That makes much more sense, I have not considered changing the data type > as I wanted to keep the changes at minimum, but your solution is even > better.  Should I leave the fix up to you or do you want me to send a v3? Could you please try it out to ensure it works for you and then send a v3? Thank you very much. Reinette