Re: [PATCH V2] x86, amd_ucode: Verify max allowed patch size before apply

[Aravind Gopalakrishnan <aravind.gopalakrishnan@amd.com>]

On 4/30/2014 1:07 AM, Jan Beulich wrote:
>>>> On 30.04.14 at 01:56, <aravind.gopalakrishnan@amd.com> wrote:
>> On 4/29/2014 4:33 PM, Aravind Gopalakrishnan wrote:
>>> On 4/29/2014 3:02 AM, Jan Beulich wrote:
>>>
>>>>> @@ -123,8 +151,17 @@ static bool_t microcode_fits(const struct
>>>>> microcode_amd *mc_amd, int cpu)
>>>>>        if ( (mc_header->processor_rev_id) != equiv_cpu_id )
>>>>>            return 0;
>>>>>    +    if ( !verify_patch_size(mc_amd->mpb_size) )
>>>>> +    {
>>>>> +        printk(XENLOG_DEBUG "microcode: patch size mismatch\n");
>>>>> +        return -E2BIG;
>>>>> +    }
>>>>> +
>>>>>        if ( mc_header->patch_id <= uci->cpu_sig.rev )
>>>>> -        return 0;
>>>>> +    {
>>>>> +        printk(XENLOG_DEBUG "microcode: patch is already at
>>>>> required level or greater.\n");
>>>>> +        return -EEXIST;
>>>>> +    }
>>>>>          printk(KERN_DEBUG "microcode: CPU%d found a matching
>>>>> microcode "
>>>>>               "update with version %#x (current=%#x)\n",
>>>> Honestly I'm rather hesitant to accept further generally useless
>>>> messages, no matter that they get printed at KERN_DEBUG only. I'd
>>>> much rather see these as well as the existing ones to be converted
>>>> to pr_debug(), thus easily enabled if someone really needs to do
>>>> debugging here. That's mainly because I (and I suppose other
>>>> developers do so to) try to run with loglvl=all wherever possible,
>>>> yet already on the 2x4-core box (not to speak of the newer 2x12-
>>>> core one) I find these rather annoying.
>>> Hmm, Okay. I'll work on this and send an updated version..
>> couple of ideas about implementing this:
> Actually I'd prefer to just go the microcode_intel.c route for now, unless
> there's a compelling reason for something more involved.
>
My thought was using a command line parameter to toggle whether we need 
debug messages to be printed or not
is easier still than having to change #define pr_debug and recompile..

Anyway, I shall use microcode_intel's method then..

-Aravind.