Message-ID: <CAOnJCULe_5v6cb_JcoPKf-UD3bVze1U=jaYeLTsMu7pFigde+A@mail.gmail.com>
Date:   Thu, 10 Feb 2022 14:42:35 -0800
From:   Atish Patra <atishp@...shpatra.org>
To:     Heiko Stuebner <heiko@...ech.de>
Cc:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        devicetree <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>, Wei Fu <wefu@...hat.com>,
        liush <liush@...winnertech.com>, Guo Ren <guoren@...nel.org>,
        Anup Patel <anup@...infault.org>,
        Drew Fustini <drew@...gleboard.org>,
        Christoph Hellwig <hch@....de>, Arnd Bergmann <arnd@...db.de>,
        Chen-Yu Tsai <wens@...e.org>,
        Maxime Ripard <maxime@...no.tech>,
        Greg Favor <gfavor@...tanamicro.com>,
        Andrea Mondelli <andrea.mondelli@...wei.com>,
        Jonathan Behrens <behrensj@....edu>,
        Xinhaoqu <xinhaoqu@...wei.com>,
        Bill Huffman <huffman@...ence.com>,
        Nick Kossifidis <mick@....forth.gr>,
        Allen Baum <allen.baum@...erantotech.com>,
        Josh Scheid <jscheid@...tanamicro.com>,
        Richard Trauben <rtrauben@...il.com>,
        Samuel Holland <samuel@...lland.org>,
        Christoph Muellner <cmuellner@...ux.com>,
        Philipp Tomsich <philipp.tomsich@...ll.eu>
Subject: Re: [PATCH v6 08/14] riscv: move boot alternatives to a slightly
 earlier position

On Wed, Feb 9, 2022 at 4:39 AM Heiko Stuebner <heiko@...ech.de> wrote:
>
> Move the application of boot alternatives to soc_early_init().
> This allows to catch more generic cases of code needing patches
> than doing it in smp_prepare_boot_cpu() and also makes it actually
> work if CONFIG_SMP is disabled for whatever reason.
>
> The position is chosen mainly as it is before the actual soc early
> init runs but also already allows accessing the devicetree
> via fdt_* functions.
>
> Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> ---
>  arch/riscv/kernel/head.S    | 2 ++
>  arch/riscv/kernel/smpboot.c | 2 --
>  2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index 2363b43312fc..0e1bb97f9749 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -10,6 +10,7 @@
>  #include <asm/thread_info.h>
>  #include <asm/page.h>
>  #include <asm/pgtable.h>
> +#include <asm/alternative.h>
>  #include <asm/csr.h>
>  #include <asm/cpu_ops_sbi.h>
>  #include <asm/hwcap.h>
> @@ -341,6 +342,7 @@ clear_bss_done:
>         call kasan_early_init
>  #endif
>         /* Start the kernel */
> +       call apply_boot_alternatives

Do you really need this early ?
if non-smp configuration is the only option, Can you do it in
setup_arch() after riscv_fill_hwcap() is called ?

By doing that, we can unify the cpu feature probing and you don't need
a separate DT parsing just for svpbmt.

>         call soc_early_init
>         tail start_kernel
>
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index a6d13dca1403..f1e4948a4b52 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -32,7 +32,6 @@
>  #include <asm/sections.h>
>  #include <asm/sbi.h>
>  #include <asm/smp.h>
> -#include <asm/alternative.h>
>
>  #include "head.h"
>
> @@ -41,7 +40,6 @@ static DECLARE_COMPLETION(cpu_running);
>  void __init smp_prepare_boot_cpu(void)
>  {
>         init_cpu_topology();
> -       apply_boot_alternatives();
>  }
>
>  void __init smp_prepare_cpus(unsigned int max_cpus)
> --
> 2.30.2
>
>
> _______________________________________________
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> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv



-- 
Regards,
Atish

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