linux-kernel - Re: [PATCH] riscv: Ensure isa-ext static keys are writable

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Message-ID: <20220816164950.vyo7iiiehhhasxpr@kamzik>
Date:   Tue, 16 Aug 2022 18:49:50 +0200
From:   Andrew Jones <ajones@...tanamicro.com>
To:     Conor.Dooley@...rochip.com
Cc:     linux-riscv@...ts.infradead.org, kvm-riscv@...ts.infradead.org,
        linux-kernel@...r.kernel.org, daolu@...osinc.com,
        jszhang@...nel.org, palmer@...belt.com, re@...z.net,
        apatel@...tanamicro.com
Subject: Re: [PATCH] riscv: Ensure isa-ext static keys are writable

On Tue, Aug 16, 2022 at 04:36:55PM +0000, Conor.Dooley@...rochip.com wrote:
> On 16/08/2022 17:30, Andrew Jones wrote:
> > riscv_isa_ext_keys[] is an array of static keys used in the unified
> > ISA extension framework. The keys added to this array may be used
> > anywhere, including in modules. Ensure the keys remain writable by
> > placing them in the data section.
> > 
> > The need to change riscv_isa_ext_keys[]'s section was found when the
> > kvm module started failing to load. Commit 8eb060e10185 ("arch/riscv:
> > add Zihintpause support") adds a static branch check for a newly
> > added isa-ext key to cpu_relax(), which kvm uses.
> > 
> > Fixes: c360cbec3511 ("riscv: introduce unified static key mechanism for ISA extensions")
> 
> Hey Drew,
> How about adding:
> 
> Reported-by: Ron Economos <re@...z.net>
> Reported-by: Anup Patel <apatel@...tanamicro.com>
> Reported-by: Conor Dooley <conor.dooley@...rochip.com>

Sure, should I repost or can those be picked up when/if the patch is
picked up?

Thanks,
drew

> 
> Thanks,
> Conor.
> 
> > Signed-off-by: Andrew Jones <ajones@...tanamicro.com>
> > ---
> >  arch/riscv/kernel/cpufeature.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index 553d755483ed..3b5583db9d80 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -28,7 +28,7 @@ unsigned long elf_hwcap __read_mostly;
> >  /* Host ISA bitmap */
> >  static DECLARE_BITMAP(riscv_isa, RISCV_ISA_EXT_MAX) __read_mostly;
> >  
> > -__ro_after_init DEFINE_STATIC_KEY_ARRAY_FALSE(riscv_isa_ext_keys, RISCV_ISA_EXT_KEY_MAX);
> > +DEFINE_STATIC_KEY_ARRAY_FALSE(riscv_isa_ext_keys, RISCV_ISA_EXT_KEY_MAX);
> >  EXPORT_SYMBOL(riscv_isa_ext_keys);
> >  
> >  /**