linux-kernel - Re: [RFC PATCH] powerpc/tlb: enable arch want batched unmap tlb flush

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Message-ID: <87wmj8pbte.fsf@mail.lhotse>
Date: Thu, 19 Sep 2024 13:22:21 +1000
From: Michael Ellerman <mpe@...erman.id.au>
To: Luming Yu <luming.yu@...ngroup.cn>, linuxppc-dev@...ts.ozlabs.org,
 linux-kernel@...r.kernel.org, npiggin@...il.com,
 christophe.leroy@...roup.eu, jialong.yang@...ngroup.cn,
 luming.yu@...il.com
Cc: Luming Yu <luming.yu@...ngroup.cn>
Subject: Re: [RFC PATCH] powerpc/tlb: enable arch want batched unmap tlb flush

Luming Yu <luming.yu@...ngroup.cn> writes:
> From: Yu Luming <luming.yu@...il.com>
>
> ppc always do its own tracking for batch tlb.

I don't think it does? :)

I think you're referring to the batch handling in 
arch/powerpc/include/asm/book3s/64/tlbflush-hash.h ?

But that's only used for 64-bit Book3S with the HPT MMU.

> By trivially enabling
> the ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH in ppc, ppc arch can re-use
> common code in rmap and reduce overhead and do optimization it could not
> have without a tlb flushing context at low architecture level.
>
> Signed-off-by: Luming Yu <luming.yu@...ngroup.cn>
> ---
>  arch/powerpc/Kconfig                |  1 +
>  arch/powerpc/include/asm/tlbbatch.h | 30 +++++++++++++++++++++++++++++
>  2 files changed, 31 insertions(+)
>  create mode 100644 arch/powerpc/include/asm/tlbbatch.h

This doesn't build:

  https://github.com/linuxppc/linux-snowpatch/actions/runs/10919442655

Can you please follow the instructions here:

  https://github.com/linuxppc/wiki/wiki/Testing-with-GitHub-Actions

Which describe how to fork our CI tree that has Github Actions
preconfigured, then you can apply your patches on top and push to github
and it will do some test builds for you. Notably it will do 32-bit
builds which is what broke here.

cheers