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Message-ID: <fa3be245-ac3c-5637-13a1-3197e78c874d@gmail.com>
Date: Wed, 18 May 2022 17:12:35 +0300
From: Oleksandr <olekstysh@...il.com>
To: Rob Herring <robh@...nel.org>, Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>
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>,
"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 17.05.22 03:27, Rob Herring wrote:
Hello Rob, all
> 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.
ok, will do
>
>> +
>> +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?
In general, yes. It is driver(frontend) domid. But, at least for now, I
don't see why we will need an additional property for that.
> Maybe xen,backend-domid or just xen,domid? I don't know Xen
> too well, so ultimately up to you all.
xen,domid sounds ambiguous to me.
xen,backend-domid sounds perfectly fine to me, I even think it fits better.
Stefano, Juergen, would you be happy with new xen,backend-domid name?
If yes, Stefano could you please clarify, would you be OK if I retained
your R-b tags (for all patches in current series which touch that
property) after doing such renaming?
>
>> + $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.
ok, will do. Could you please clarify, shall I use?
unevaluatedProperties: false
or
unevaluatedProperties:
type: object
I am not too familiar with this stuff. Both variants seem to pass
validation.
Thank you.
>
>> +
>> required:
>> - compatible
>> - reg
>> --
>> 2.7.4
>>
>>
--
Regards,
Oleksandr Tyshchenko
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