From: Marc Zyngier <maz@kernel.org>
To: Mark Brown <broonie@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/4] arm64: Document requirements for fine grained traps at boot
Date: Thu, 08 Apr 2021 18:00:14 +0100 [thread overview]
Message-ID: <87tuogogo1.wl-maz@kernel.org> (raw)
In-Reply-To: <20210401180942.35815-2-broonie@kernel.org>
On Thu, 01 Apr 2021 19:09:39 +0100,
Mark Brown <broonie@kernel.org> wrote:
>
> The arm64 FEAT_FGT extension introduces a set of traps to EL2 for accesses
> to small sets of registers and instructions from EL1 and EL0, access to
> which is controlled by EL3. Require access to it so that it is
> available to us in future and so that we can ensure these traps are
> disabled during boot.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> Documentation/arm64/booting.rst | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/Documentation/arm64/booting.rst b/Documentation/arm64/booting.rst
> index 7552dbc1cc54..92ec0bea1af5 100644
> --- a/Documentation/arm64/booting.rst
> +++ b/Documentation/arm64/booting.rst
> @@ -270,6 +270,12 @@ Before jumping into the kernel, the following conditions must be met:
> having 0b1 set for the corresponding bit for each of the auxiliary
> counters present.
>
> + For CPUs with the Fine Grained Traps (FEAT_FGT) extension present:
> +
> + - If EL3 is present and the kernel is entered at EL2:
> +
> + - SCR_EL3.FGTEn (bit 27) must be initialised to 0b1.
> +
> The requirements described above for CPU mode, caches, MMUs, architected
> timers, coherency and system registers apply to all CPUs. All CPUs must
> enter the kernel in the same exception level.
Acked-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
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next prev parent reply other threads:[~2021-04-08 17:02 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-01 18:09 [PATCH v2 0/4] arm64: Booting clarifications and fine grained traps setup Mark Brown
2021-04-01 18:09 ` [PATCH v2 1/4] arm64: Document requirements for fine grained traps at boot Mark Brown
2021-04-08 17:00 ` Marc Zyngier [this message]
2021-04-01 18:09 ` [PATCH v2 2/4] arm64: Disable fine grained traps on boot Mark Brown
2021-04-08 17:00 ` Marc Zyngier
2021-04-01 18:09 ` [PATCH v2 3/4] arm64: Require that system registers at all visible ELs be initialized Mark Brown
2021-04-08 17:02 ` Marc Zyngier
2021-04-01 18:09 ` [PATCH v2 4/4] arm64: Document values for system registers on boot Mark Brown
2021-04-08 17:16 ` Marc Zyngier
2021-04-08 17:33 ` Mark Brown
2021-04-08 17:59 ` (subset) [PATCH v2 0/4] arm64: Booting clarifications and fine grained traps setup Catalin Marinas
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