From: Mark Brown <broonie@kernel.org>
To: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v7 3/4] arm64: Don't use KPTI where we have E0PD
Date: Fri, 8 Nov 2019 14:10:17 +0000 [thread overview]
Message-ID: <20191108141017.GE5532@sirena.co.uk> (raw)
In-Reply-To: <091c5d4c-0292-0dde-043f-f5f9f0fac3af@arm.com>
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On Thu, Nov 07, 2019 at 03:03:49PM +0000, Suzuki K Poulose wrote:
> On 07/11/2019 14:37, Mark Brown wrote:
> > > Given that this gets run on all individual CPUs, via unmap_kernel_at_el0()
> > > and the decision of choosing KPTI is affected by the lack of the E0PD feature
> > > when it is helpful, having CPU local check is fine. Also this gives us the
> > > advantage of choosing an nG mapping when the boot CPU indicates the need.
> > Well, it's mainly the fact that this runs really early on in boot before
> > the cpufeature code has fully initialized so as with the existing code
> > immediately below for identifying TX1 we can't rely on the cpufeature
> > code being done.
> Yes, I acknowledge that. I was writing it down to clear why this was
> fine and why it has its own advantage. This may not be obvious for
> someone who reads it later. So having this in a comment helps to
> avoid staring at it.
Yes... my point was more about idiom and urgency, especially given that
this code is moved later in the patch series.
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next prev parent reply other threads:[~2019-11-08 14:10 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-06 13:00 [PATCH v7 0/4] E0PD support Mark Brown
2019-11-06 13:00 ` [PATCH v7 1/4] arm64: Add initial support for E0PD Mark Brown
2019-11-07 10:12 ` Suzuki K Poulose
2019-11-07 11:55 ` Mark Brown
2019-11-06 13:00 ` [PATCH v7 2/4] arm64: Factor out checks for KASLR in KPTI code into separate function Mark Brown
2019-11-06 13:00 ` [PATCH v7 3/4] arm64: Don't use KPTI where we have E0PD Mark Brown
2019-11-07 12:01 ` Suzuki K Poulose
2019-11-07 14:37 ` Mark Brown
2019-11-07 15:03 ` Suzuki K Poulose
2019-11-08 14:10 ` Mark Brown [this message]
2019-11-07 14:48 ` Mark Brown
2019-11-06 13:00 ` [PATCH v7 4/4] arm64: Use a variable to store non-global mappings decision Mark Brown
2019-11-07 11:11 ` Suzuki K Poulose
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