[PATCH RFC 06/10] virprocess: Core Scheduling support

[Michal Prívozník]

On 5/23/22 19:00, Daniel P. Berrangé wrote:
> On Mon, May 09, 2022 at 05:02:13PM +0200, Michal Privoznik wrote:
>> Since its 5.14 release the Linux kernel allows userspace to
>> define trusted groups of processes/threads that can run on
>> sibling Hyper Threads (HT) at the same time. This is to mitigate
>> side channel attacks like L1TF or MDS. If there are no tasks to
>> fully utilize all HTs, then a HT will idle instead of running a
>> task from another (un-)trusted group.
>>
>> On low level, this is implemented by cookies (effectively an UL
>> value): processes in the same trusted group share the same cookie
>> and cookie is unique to the group. There are four basic
>> operations:
>>
>> 1) PR_SCHED_CORE_GET -- get cookie of given PID,
>> 2) PR_SCHED_CORE_CREATE -- create a new unique cookie for PID,
>> 3) PR_SCHED_CORE_SHARE_TO -- push cookie of the caller onto
>>    another PID,
>> 4) PR_SCHED_CORE_SHARE_FROM -- pull cookie of another PID into
>>    the caller.
>>
>> Since a system where the code is built can be different to the
>> one where the code is ran let's provide declaration of some
>> values. It's not unusual for distros to ship older linux-headers
>> than the actual kernel.
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
>>  src/libvirt_private.syms |   4 ++
>>  src/util/virprocess.c    | 124 +++++++++++++++++++++++++++++++++++++++
>>  src/util/virprocess.h    |   8 +++
>>  3 files changed, 136 insertions(+)
> 
> Reviewed-by: Daniel P. Berrangé <berrange at redhat.com>
> 
> 
>> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
>> index 36d7df050a..cd4f3fc7e7 100644
>> --- a/src/util/virprocess.c
>> +++ b/src/util/virprocess.c
>> @@ -57,6 +57,10 @@
>>  # include <windows.h>
>>  #endif
>>  
>> +#if WITH_CAPNG
> 
> This feels odd - what relation has CAPNG got with prctl ?

Nothing, it's a blind copy from virutil.c O:-)
Consider changed to #ifdef __linux__

Michal