Re: [PATCH v6 00/18] x86,fs/resctrl: Add kernel-mode (e.g., PLZA) support to the resctrl subsystem

[Drew Fustini <fustini@kernel.org>]

On Thu, Oct 01, 2026 at 10:10:23AM -0500, Babu Moger wrote:
> 
> Hi All,
> 
> This series adds support for AMD's Privilege-Level Zero Association
> (PLZA) so kernel work can use a separate resource allocation and/or
> monitoring association from the user task, and wires it up through a
> small generic "kernel mode" (kmode) layer in fs/resctrl so future
> architectures can plug in without touching (hopefully) core resctrl.

Hi Babu,

Yunhui Cui (cc'd) recently proposed a RISC-V extension [1] with similar
functionality. It adds a new CSR with a RCID (like CLOSID) and MCID
(like RMID) to use when the cpu switches to the privilege level that the
kernel runs in (supervisor-mode in RISC-V terminology). The srmcfg_assoc
register is defined as:

    Bits      Field
    --------  --------
    11:0      RCID
    12        RCID_EN
    15:13     Reserved
    27:16     MCID
    28        MCID_EN
    30:29     Reserved
    31        ASSOC_EN

It is similar enough to PLZA that I believe that this series could work
for RISC-V. Hopefully Yunhui Cui can comment further.

Thanks,
Drew

[1] https://lists.riscv.org/g/tech-privileged/message/3088