From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 4/6] s390: add system call to run tasks with modified
 branch prediction
Date: Wed, 17 Jan 2018 11:05:30 +0100
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Cc: Heiko Carstens <heiko.carstens@de.ibm.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jon Masters <jcm@redhat.com>,
        Marcus Meissner <meissner@suse.de>,
        Jiri Kosina <jkosina@suse.cz>
To: Florian Weimer <fweimer@redhat.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org,
        kvm@vger.kernel.org
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On 17/01/2018 11:03, Florian Weimer wrote:
> On 01/17/2018 10:48 AM, Martin Schwidefsky wrote:
>>          rc = syscall(__NR_s390_modify_bp);
>>          if (rc) {
>>                  perror("s390_modify_bp");
>>                  exit(EXIT_FAILURE);
>>          }
> 
> 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