linux-kernel - Re: [PATCH v7] arm64: Add support for new control bits CTR_EL0.DIC and CTR

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Message-ID: <20180309134439.76b43chxnrw7okrw@lakrids.cambridge.arm.com>
Date:   Fri, 9 Mar 2018 13:44:40 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Shanker Donthineni <shankerd@...eaurora.org>
Cc:     Will Deacon <will.deacon@....com>,
        Robin Murphy <robin.murphy@....com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Catalin Marinas <catalin.marinas@....com>,
        kvmarm <kvmarm@...ts.cs.columbia.edu>,
        Marc Zyngier <marc.zyngier@....com>,
        Vikram Sethi <vikrams@...eaurora.org>,
        Philip Elcan <pelcan@...eaurora.org>
Subject: Re: [PATCH v7] arm64: Add support for new control bits CTR_EL0.DIC
 and CTR_EL0.IDC

On Wed, Mar 07, 2018 at 09:00:08AM -0600, Shanker Donthineni wrote:
>  static inline void __flush_icache_all(void)
>  {
> -	asm("ic	ialluis");
> -	dsb(ish);
> +	/* Instruction cache invalidation is not required for I/D coherence? */
> +	if (!cpus_have_const_cap(ARM64_HAS_CACHE_DIC)) {
> +		asm("ic	ialluis");
> +		dsb(ish);
> +	}
>  }

I don't think we need the comment here. We don't have this in the other
cases we look at the ARM64_HAS_CACHE_{IDC,DIC} caps.

This would also be slightly nicer as an early return:

static inline void __flush_icache_all(void)
{
	if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC))
		return;
	
	asm("ic ialluis");
	dsb(ish);
}

... which minimizes indentation, and the diffstat.

The rest looks fine to me, so with the above changes:

Reviewed-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.