Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c

From	Mark Rutland <mark.rutland@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c
Date	2015-12-01 20:00 +0100
Message-ID	<qAYjE-4To-19@gated-at.bofh.it> (permalink)
References	(3 earlier) <qAVF7-3r6-5@gated-at.bofh.it> <qAW8a-3BH-17@gated-at.bofh.it> <qAX4e-4do-5@gated-at.bofh.it> <qAXnA-4kq-13@gated-at.bofh.it> <qAXGW-4Gh-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Tue, Dec 01, 2015 at 06:10:17PM +0000, Suzuki K. Poulose wrote:
> On 01/12/15 17:52, Mark Rutland wrote:
> >On Tue, Dec 01, 2015 at 05:38:54PM +0000, Suzuki K. Poulose wrote:
> >>On 01/12/15 16:31, Mark Rutland wrote:
> >
> >[...]
> >
> >>>We need stuck-in-the-kernel flag to account for CPUs which didn't manage
> >>>to turn the MMU on (which are either in the spin-table, or failed when
> >>>they were individually onlined).
> >>
> >>Did you mean to say "turn the MMU off" ?
> >
> >No, I mean CPUs which were unable to turn the MMU on in the first place.
> >Perhaps they entered the spin-table but were never individually onlined,
> >perhaps they didn't support the kernel page size, etc.
> >
> >When CPUs exit the kernel via PSCI they never switch the MMU off within
> >the kernel.
> 
> OK. So the flag will also be used for CPUs which are stuck-in-the-kernel
> with MMU turned on. e.g, a CPU (using spin-table) we try to bring down
> in kill_cpu_early(). Correct ?

Yes.

We'd also pad it such that nothing else shares the same writeback
granule, and when writing to it with the MMU off we can invalidate the
stale cached copy.

Thanks,
Mark.
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Thread

[PATCH v2 0/6] arm64: cpufeature: Add sanity check for ASIDBits "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 4/6] arm64: Add hook for checking early CPU features "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 1/6] arm64: Introduce kill_cpu_early "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
    Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 16:30 +0100
      Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 17:10 +0100
        Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 17:40 +0100
          Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 18:40 +0100
            Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 19:00 +0100
              Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-01 19:20 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-01 20:00 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-12-03 17:40 +0100
                Re: [PATCH v2 2/6] arm64: Move kill_cpu_early to smp.c Mark Rutland <mark.rutland@arm.com> - 2015-12-03 18:10 +0100
  [PATCH v2 6/6] arm64: Ensure the secondary CPUs have safe ASIDBits size "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100
  [PATCH v2 5/6] arm64: Add helper for extracting ASIDBits "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-12-01 16:20 +0100

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