From: Catalin Marinas <catalin.marinas@arm.com>
To: Mark Brown <broonie@kernel.org>
Cc: Will Deacon <will@kernel.org>, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2] arm64: Add initial support for E0PD
Date: Sat, 29 Jun 2019 14:21:29 +0100 [thread overview]
Message-ID: <20190629132128.fdv4f23sjpsaxypg@mbp> (raw)
In-Reply-To: <20190628173920.GA2793@sirena.org.uk>
Hi Mark,
On Fri, Jun 28, 2019 at 06:39:20PM +0100, Mark Brown wrote:
> On Fri, Jun 28, 2019 at 05:36:42PM +0100, Catalin Marinas wrote:
> > On Fri, Jun 28, 2019 at 01:30:40PM +0100, Mark Brown wrote:
>
> > > It's largely on the general theory that it's better to carry less out of
> > > tree code - there's less diff to manage, less chance of collisions with
> > > other work (in either direction), and less pending review to worry about.
> > > So long as something represents forward progress I tend to work on the
> > > basis of why not rather than why.
>
> > A reason is that once we add the support for disabling kpti based on
> > the E0PD feature, this patch may turn out to be slightly different (for
> > example, you may add a common has_e0pd() check that is called from
> > both unmap_kernel_at_el0() and the E0PD arm64_features[] entry). Given
>
> Hrm, I don't really get that - incremental patches can always be done
> (indeed they're often really helpful for people trying to understand how
> the code got to be the way it is).
Sorry, I wasn't clear enough. I'm perfectly fine to incremental patches
and encourage them as part of a series achieving an end goal. Here the
end goal (and the reason behind this architecture feature) is to be able
to safely disable KPTI in favour of a hardware-based mitigation. Your
one-patch series does not achieve this yet, so I suggest we don't merge
this until we have the other part of the series.
--
Catalin
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prev parent reply other threads:[~2019-06-29 13:21 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-27 14:15 [PATCH v2] arm64: Add initial support for E0PD Mark Brown
2019-06-28 11:04 ` Will Deacon
2019-06-28 12:30 ` Mark Brown
2019-06-28 16:36 ` Catalin Marinas
2019-06-28 17:39 ` Mark Brown
2019-06-29 13:21 ` Catalin Marinas [this message]
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