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

From: <Conor.Dooley@microchip.com>
To: <mail@conchuod.ie>, <paul.walmsley@sifive.com>,
	<palmer@dabbelt.com>, <palmer@rivosinc.com>,
	<aou@eecs.berkeley.edu>, <sudeep.holla@arm.com>,
	<catalin.marinas@arm.com>, <will@kernel.org>,
	<gregkh@linuxfoundation.org>, <rafael@kernel.org>
Cc: <Daire.McNamara@microchip.com>, <niklas.cassel@wdc.com>,
	<damien.lemoal@opensource.wdc.com>, <geert@linux-m68k.org>,
	<zong.li@sifive.com>, <kernel@esmil.dk>, <hahnjo@hahnjo.de>,
	<guoren@kernel.org>, <anup@brainfault.org>,
	<atishp@atishpatra.org>, <heiko@sntech.de>,
	<philipp.tomsich@vrull.eu>, <robh@kernel.org>, <maz@kernel.org>,
	<viresh.kumar@linaro.org>, <linux-riscv@lists.infradead.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>, <Brice.Goglin@inria.fr>
Subject: Re: [PATCH v4 0/2] Fix RISC-V's arch-topology reporting
Date: Sat, 16 Jul 2022 13:35:09 +0000	[thread overview]
Message-ID: <b5abb978-75d4-962b-c6de-fd75dc6cc537@microchip.com> (raw)
In-Reply-To: <20220715175155.3567243-1-mail@conchuod.ie>

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@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
> 

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