Re: [RESEND PATCH v4 03/15] x86/resctrl: Add data structures and definitions for PLZA configuration

[Moger, Babu]

Hi Reinette,

On 8/11/2026 6:51 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 8/11/26 2:10 PM, Babu Moger wrote:
> > On 8/10/26 21:58, Reinette Chatre wrote:
> > > On 7/7/26 2:50 PM, Babu Moger wrote:
> > > > Privilege Level Zero Association (PLZA) allows the kernel to use a
> > > > different CLOSID (and optionally RMID) than user mode on entry to kernel
> > > > mode. The CLOSID/RMID association is programmed per CPU via
> > >
> > > CLOSID is also optional, no? I am not able to recall now why this is not made
> > > optional in this implementation though. Could you please remind me and add
> > > it to the changelog for next time?
> >
> >
> > Yes, CLOSID is optional as well. Since PLZA was primarily focused on
> > allocation, I hadn't considered that use case initially. However,
> > there may be scenarios where a user wants to monitor kernel activity
> > without affecting or changing the existing allocation configuration.
> > That would introduce an additional operating mode(See below).
>
> ok.
>
> I think doing so will simplify supporting the different modes across systems
> that may not support allocation or monitoring.

Ack.

> > INHERIT_CTRL_AND_MON:
> > Kernel work inherits the allocation and monitoring from the user space
> > task. On x86 this means that kernel work shares the same CLOSID and
> > RMID as the user space task. This matches today's resctrl behavior.
> >
> > GLOBAL_ASSIGN_CTRL_INHERIT_MON_PER_CPU:
> > Kernel work uses a globally assigned allocation while monitoring is
> > inherited from the user space task. On x86 this means a CLOSID is
> > assigned for kernel work and the RMID is inherited from the user space
> > task. Default scope is all online CPUs; a subset may be selected via
> > the resctrl group interface. A CTRL_MON group is bound to this mode.
> >
> > GLOBAL_ASSIGN_CTRL_ASSIGN_MON_PER_CPU:
> > Kernel work uses globally assigned allocation and monitoring. On x86
> > this means both CLOSID and RMID are assigned for kernel work. Default
> > scope is all online CPUs; a subset may be selected via the resctrl
> > group interface. A CTRL_MON or MON group is bound to this mode.
> >
> > GLOBAL_INHERIT_CTRL_ASSIGN_MON_PER_CPU:   <--- New mode
> > Kernel work inherits the allocation from user task and monitoring is
> > globally assigned for kernel work. On x86 this means that kernel
> > work shares the same CLOSID as user task and kernel work user
> > globally assigned RMID. A MON group is bound to this mode.
>
> I provided comments about this text in following patch. Apart from that,
> I think a CTRL_MON or MON group could be assigned to this mode?

Yes. It can be CTRL_MON or MON group.

thanks
Babu