[PATCH v4 0/2] Fix RISC-V's arch-topology reporting

[Conor.Dooley at microchip.com]

On 15/07/2022 18:51, Conor Dooley wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> From: Conor Dooley <conor.dooley at microchip.com>
> 
> Hey all,
> It's my first time messing around with arch/ code at all, let alone
> more than one arch, so forgive me if I have screwed up how to do a
> migration like this.
> 
> The goal here is the fix the incorrectly reported arch topology on
> RISC-V which seems to have been broken since it was added.
> cpu, package and thread IDs are all currently reported as -1, so tools
> like lstopo think systems have multiple threads on the same core when
> this is not true:
> https://github.com/open-mpi/hwloc/issues/536
> 
> arm64's topology code basically applies to RISC-V too, so it has been
> made generic along with the removal of MPIDR related code, which
> appears to be redudant code since '3102bc0e6ac7 ("arm64: topology: Stop
> using MPIDR for topology information")' replaced the code that actually
> interacted with MPIDR with default values.
> 
> I only built tested for arm{,64} , so hopefully it is not broken when
> used. Testing on both arm64 & !SMP RISC-V would really be appreciated!

FWIW, I pushed it to a branch for the sake of LKP testing and all
archs + randconfigs built fine.
Thanks,
Conor.

> 
> For V2, I dropped the idea of doing a RISC-V specific implementation
> followed by a move to the generic code & just went for the more straight
> forward method of moving to the shared version first. I also dropped the
> RFC.
> 
> V3 moves store_cpu_topology()'s definition down inside the arch check
> alongside the init function so that boot on 32bit arm is not broken.
> 
> V4 has moved the RISC-V boot hart's call to store_cpu_topology() later
> into the boot process it is now right before SMP is brought up (or not
> in the case of !SMP). This prevents calling detect_cache_attributes()
> while we cannot allocate memory.
> 
> V4 is also rebased on next-20220715 to get Sudeep's most recent
> arch_topology patchset.
> 
> Thanks,
> Conor
> 
> Conor Dooley (2):
>   arm64: topology: move store_cpu_topology() to shared code
>   riscv: topology: fix default topology reporting
> 
>  arch/arm64/kernel/topology.c | 40 ------------------------------------
>  arch/riscv/Kconfig           |  2 +-
>  arch/riscv/kernel/smpboot.c  |  3 ++-
>  drivers/base/arch_topology.c | 19 +++++++++++++++++
>  4 files changed, 22 insertions(+), 42 deletions(-)
> 
> 
> base-commit: 6014cfa5bf32cf8c5c58b3cfd5ee0e1542c8a825
> --
> 2.37.1
>