linux-kernel - Re: [RFC PATCH v4 2/2] arm64: tlb: Use the TLBI RANGE feature in arm64

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Date:   Tue, 7 Jul 2020 18:46:12 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Zhenyu Ye <yezhenyu2@...wei.com>, will@...nel.org,
        suzuki.poulose@....com, steven.price@....com, guohanjun@...wei.com,
        olof@...om.net, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, arm@...nel.org, xiexiangyou@...wei.com,
        prime.zeng@...ilicon.com, zhangshaokun@...ilicon.com,
        kuhn.chenqun@...wei.com
Subject: Re: [RFC PATCH v4 2/2] arm64: tlb: Use the TLBI RANGE feature in
 arm64

On Tue, Jul 07, 2020 at 06:43:35PM +0100, Marc Zyngier wrote:
> On 2020-07-07 18:36, Catalin Marinas wrote:
> > On Mon, Jun 01, 2020 at 10:47:13PM +0800, Zhenyu Ye wrote:
> > > @@ -59,6 +69,47 @@
> > >  		__ta;						\
> > >  	})
> > > 
> > > +/*
> > > + * __TG defines translation granule of the system, which is decided
> > > by
> > > + * PAGE_SHIFT.  Used by TTL.
> > > + *  - 4KB	: 1
> > > + *  - 16KB	: 2
> > > + *  - 64KB	: 3
> > > + */
> > > +#define __TG	((PAGE_SHIFT - 12) / 2 + 1)
> > 
> > Nitpick: maybe something like __TLBI_TG to avoid clashes in case someone
> > else defines a __TG macro.
> 
> I have commented on this in the past, and still maintain that this
> would be better served by a switch statement similar to what is used
> for TTL already (I don't think this magic formula exists in the
> ARM ARM).

Good point, it would be cleaner indeed.

-- 
Catalin