Re: [PATCHv3 08/11] arm64: Check for selected granule support

From	"Suzuki K. Poulose" <Suzuki.Poulose@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCHv3 08/11] arm64: Check for selected granule support
Date	2015-10-15 11:50 +0200
Message-ID	<qjNkB-2zQ-3@gated-at.bofh.it> (permalink)
References	<qjspQ-5qz-3@gated-at.bofh.it> <qjspQ-5qz-9@gated-at.bofh.it> <qjy2f-5jz-13@gated-at.bofh.it>
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On 14/10/15 18:24, Mark Rutland wrote:

>> - * other registers depend on the function called upon completion
>> + * Other registers depend on the function called upon completion.
>> + *
>> + * Checks if the selected granule size is supported by the CPU.
>> + * If it doesn't park the CPU
>
> Nit: "If it isn't, park the CPU."

OK

>
>>    */
>> +#if	defined(CONFIG_ARM64_64K_PAGES)
>> +
>> +#define id_aa64mmfr0_tgran_shift	ID_AA64MMFR0_TGRAN64_SHIFT
>> +#define id_aa64mmfr0_tgran_on		ID_AA64MMFR0_TGRAN64_ON
>> +
>> +#else
>> +
>> +#define id_aa64mmfr0_tgran_shift	ID_AA64MMFR0_TGRAN4_SHIFT
>> +#define id_aa64mmfr0_tgran_on		ID_AA64MMFR0_TGRAN4_ON
>
> Any reason for not using upper-case names for the macros?

Nothing in particular. I had them in upper-case in the previous version,
changed it here ;) for absolutely no reason. I could switch it back.

> Given they're local you could just call them TGRAN_SHIFT and TRGRAN_ON
> to make the asm slightly nicer.

Given Jeremy's suggestion to add something to the EFI stub, I will retain
the original definition with all upper-case and define it somewhere in
a header so that we can reuse it.

>> +
>> +__no_granule_support:
>> +	wfe
>> +	b __no_granule_support
>> +ENDPROC(__no_granule_support)
>
> Other than the above, this loogs fine to me.
>
> In future it would be nice if we could somehow signal that these dead
> CPUs are trapped in the kernel -- we should have some kind of canary
> mechanism for that. That needn't block this patch, though.

Yes, we should.

Thanks for the review
Suzuki

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Thread

[PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2015-10-14 13:30 +0200
  Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-14 19:30 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-14 19:40 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 11:50 +0200
      Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 12:40 +0200
  Re: [PATCHv3 08/11] arm64: Check for selected granule support Jeremy Linton <jeremy.linton@arm.com> - 2015-10-14 23:20 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 11:50 +0200
    Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 12:50 +0200
      Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 13:30 +0200
        Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 14:40 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 15:00 +0200
            Re: [PATCHv3 08/11] arm64: Check for selected granule support Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-16 10:10 +0200
        Re: [PATCHv3 08/11] arm64: Check for selected granule support Jeremy Linton <jeremy.linton@arm.com> - 2015-10-15 16:50 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support "Suzuki K. Poulose" <Suzuki.Poulose@arm.com> - 2015-10-15 17:10 +0200
          Re: [PATCHv3 08/11] arm64: Check for selected granule support Mark Rutland <mark.rutland@arm.com> - 2015-10-15 17:20 +0200
            Re: [PATCHv3 08/11] arm64: Check for selected granule support Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-10-16 10:20 +0200

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