Re: [PATCH 4/6] s390: add system call to run tasks with modified branch prediction

[Paolo Bonzini]

On 17/01/2018 11:03, Florian Weimer wrote:
> On 01/17/2018 10:48 AM, Martin Schwidefsky wrote:
>> ÂÂÂÂÂÂÂÂ rc = syscall(__NR_s390_modify_bp);
>> ÂÂÂÂÂÂÂÂ if (rc) {
>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ perror("s390_modify_bp");
>> ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ exit(EXIT_FAILURE);
>> ÂÂÂÂÂÂÂÂ }
> 
> Isn't this traditionally done through personality or prctl?
> 
> This looks like something other architectures may want as well.

Yes, Intel would want to have a prctl or similar to enable STIBP
(single-thread indirect branch predictor).

Paolo