Re: [PATCH 6/6] x86/bugs: Clean-up verw mitigations

[Daniel Sneddon]

On 10/2/24 07:20, Nikolay Borisov wrote:
>> +	if (boot_cpu_has_bug(X86_BUG_MDS)) {
>>   		mds_mitigation = MDS_MITIGATION_FULL;
>>   		mds_select_mitigation();
>> +	}  else {
>> +		mds_mitigation = MDS_MITIGATION_OFF;
>>   	}
> 
> BUt with this logic if CONFIG_MITIGATION_MDS is deselected meaning 
> mds_mitigations will have the value MDS_MITIGATION_OFF, yet now you will 
> set it to _FULL thereby overriding the compile-time value of the user. 
> So shouldn't this condition be augmented to alsoo consider 
> CONFIG_MITIGATION_MDS compile time value?

CONFIG_MITIGATION_MDS is used to set the value of the mds_mitigation variable.
Same goes for all the other mitigations touched here. Those variables are
checked in verw_mitigations_disabled() which is called just before this code. If
all of them are configured off, we return without enabling any of the mitigations.