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Message-ID: <20220517002750.GA3638680-robh@kernel.org>
Date: Mon, 16 May 2022 19:27:50 -0500
From: Rob Herring <robh@...nel.org>
To: Oleksandr Tyshchenko <olekstysh@...il.com>
Cc: xen-devel@...ts.xenproject.org,
virtualization@...ts.linux-foundation.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Jason Wang <jasowang@...hat.com>,
Krzysztof Kozlowski <krzk+dt@...nel.org>,
Julien Grall <julien@....org>, Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
"Michael S. Tsirkin" <mst@...hat.com>,
Christoph Hellwig <hch@...radead.org>,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH V2 5/7] dt-bindings: Add xen,dev-domid property
description for xen-grant DMA ops
On Sat, May 07, 2022 at 09:19:06PM +0300, Oleksandr Tyshchenko wrote:
> From: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
>
> Introduce Xen specific binding for the virtualized device (e.g. virtio)
> to be used by Xen grant DMA-mapping layer in the subsequent commit.
>
> This binding indicates that Xen grant mappings scheme needs to be
> enabled for the device which DT node contains that property and specifies
> the ID of Xen domain where the corresponding backend resides. The ID
> (domid) is used as an argument to the grant mapping APIs.
>
> This is needed for the option to restrict memory access using Xen grant
> mappings to work which primary goal is to enable using virtio devices
> in Xen guests.
>
> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>
> ---
> Changes RFC -> V1:
> - update commit subject/description and text in description
> - move to devicetree/bindings/arm/
>
> Changes V1 -> V2:
> - update text in description
> - change the maintainer of the binding
> - fix validation issue
> - reference xen,dev-domid.yaml schema from virtio/mmio.yaml
> ---
> .../devicetree/bindings/arm/xen,dev-domid.yaml | 37 ++++++++++++++++++++++
> Documentation/devicetree/bindings/virtio/mmio.yaml | 7 ++++
> 2 files changed, 44 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/arm/xen,dev-domid.yaml
>
> diff --git a/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml b/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml
> new file mode 100644
> index 00000000..750e89e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml
> @@ -0,0 +1,37 @@
> +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/arm/xen,dev-domid.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Xen specific binding for virtualized devices (e.g. virtio)
> +
> +maintainers:
> + - Stefano Stabellini <sstabellini@...nel.org>
> +
> +select: true
Omit. No need to apply this on every single node.
> +
> +description:
> + This binding indicates that Xen grant mappings need to be enabled for
> + the device, and it specifies the ID of the domain where the corresponding
> + device (backend) resides. The property is required to restrict memory
> + access using Xen grant mappings.
> +
> +properties:
> + xen,dev-domid:
I kind of think 'dev' is redundant. Is there another kind of domid
possible? Maybe xen,backend-domid or just xen,domid? I don't know Xen
too well, so ultimately up to you all.
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + The domid (domain ID) of the domain where the device (backend) is running.
> +
> +additionalProperties: true
> +
> +examples:
> + - |
> + virtio@...0 {
> + compatible = "virtio,mmio";
> + reg = <0x3000 0x100>;
> + interrupts = <41>;
> +
> + /* The device is located in Xen domain with ID 1 */
> + xen,dev-domid = <1>;
> + };
> diff --git a/Documentation/devicetree/bindings/virtio/mmio.yaml b/Documentation/devicetree/bindings/virtio/mmio.yaml
> index 10c22b5..29a0932 100644
> --- a/Documentation/devicetree/bindings/virtio/mmio.yaml
> +++ b/Documentation/devicetree/bindings/virtio/mmio.yaml
> @@ -13,6 +13,9 @@ description:
> See https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio for
> more details.
>
> +allOf:
> + - $ref: /schemas/arm/xen,dev-domid.yaml#
> +
> properties:
> compatible:
> const: virtio,mmio
> @@ -33,6 +36,10 @@ properties:
> description: Required for devices making accesses thru an IOMMU.
> maxItems: 1
>
> + xen,dev-domid:
> + description: Required when Xen grant mappings need to be enabled for device.
> + $ref: /schemas/types.yaml#/definitions/uint32
No need to define the type again nor describe it again.
Instead, just change additionalProperties to unevaluateProperties in
this doc. The diff is the latter takes $ref's into account.
> +
> required:
> - compatible
> - reg
> --
> 2.7.4
>
>
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