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

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(a)redhat.com&gt; > --- > 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(a)redhat.com&gt; > 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 ?