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Date:   Wed, 26 Jan 2022 23:19:08 +0000
From:   David Brazdil <dbrazdil@google.com>
To:     Rob Herring <robh+dt@kernel.org>
Cc:     Rob Herring <robh+dt@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Frank Rowand <frowand.list@gmail.com>,
        Will Deacon <will@kernel.org>,
        Andrew Scull <ascull@google.com>,
        Wedson Almeida Filho <wedsonaf@google.com>,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH v7 1/2] dt-bindings: reserved-memory: Open Profile for
 DICE
Message-ID: <YfHW7GcINVlB/3Ur@google.com>
References: <20220126231237.529308-1-dbrazdil@google.com>
 <20220126231237.529308-2-dbrazdil@google.com>
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Hi Rob,

On Wed, Jan 26, 2022 at 11:12:36PM +0000, David Brazdil wrote:
> Add DeviceTree bindings for Open Profile for DICE, an open protocol for
> measured boot. Firmware uses DICE to measure the hardware/software
> combination and generates Compound Device Identifier (CDI) certificates.
> These are stored in memory and the buffer is described in the DT as
> a reserved memory region compatible with 'google,open-dice'.
> 
> 'no-map' is required to ensure the memory region is never treated by
> the kernel as system memory.
> 
> Signed-off-by: David Brazdil <dbrazdil@google.com>
> ---
>  .../reserved-memory/google,open-dice.yaml     | 46 +++++++++++++++++++
>  1 file changed, 46 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reserved-memory/google,open-dice.yaml
> 
> diff --git a/Documentation/devicetree/bindings/reserved-memory/google,open-dice.yaml b/Documentation/devicetree/bindings/reserved-memory/google,open-dice.yaml
> new file mode 100644
> index 000000000000..257a0b51994a
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reserved-memory/google,open-dice.yaml
> @@ -0,0 +1,46 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/reserved-memory/google,open-dice.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Open Profile for DICE Device Tree Bindings
> +
> +description: |
> +  This binding represents a reserved memory region containing data
> +  generated by the Open Profile for DICE protocol.
> +
> +  See https://pigweed.googlesource.com/open-dice/
> +
> +maintainers:
> +  - David Brazdil <dbrazdil@google.com>
> +
> +allOf:
> +  - $ref: "reserved-memory.yaml"
> +
> +properties:
> +  compatible:
> +    const: google,open-dice
> +
> +  reg:
> +    description: page-aligned region of memory containing DICE data
> +
> +required:
> +  - compatible
> +  - reg
> +  - no-map

You already gave this a Reviewed-by in v6. Just want to mention that I
didn't pick it up because I added a required no-map here. It was always
included in our DTs but I made it required because the kernel should
never treat that region as system memory. The kernel will warn when the
driver tries to wipe the memory otherwise.

David