Re: [RFC PATCH 3/6] dt-bindings: xen: Add xen,dev-domid property description for xen-virtio layer

[Oleksandr <olekstysh@xxxxxxxxx>]

On 16.04.22 01:01, Stefano Stabellini wrote:

Hello Stefano


> On Thu, 14 Apr 2022, Oleksandr Tyshchenko wrote:
> > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> >
> > Introduce Xen specific binding for the virtio-mmio device to be used
> > by Xen virtio support driver in a subsequent commit.
> >
> > This binding specifies the ID of Xen domain where the corresponding
> > device (backend) resides. This is needed for the option to restrict
> > memory access using Xen grant mappings to work.
> >
> > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > ---
> >   .../devicetree/bindings/virtio/xen,dev-domid.yaml  | 39 ++++++++++++++++++++++
> >   1 file changed, 39 insertions(+)
> >   create mode 100644 Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml 
> > b/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml
> > new file mode 100644
> > index 00000000..78be993
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/virtio/xen,dev-domid.yaml
> > @@ -0,0 +1,39 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only or BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/virtio/xen,dev-domid.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Xen specific binding for the virtio device
> > +
> > +maintainers:
> > +  - Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
> > +
> > +select: true
> > +
> > +description:
> > +  This binding specifies the ID of Xen domain where the corresponding device
> > +  (backend) resides. This is needed for the option to restrict memory access
> > +  using Xen grant mappings to work.
> > +
> > +  Note that current and generic "iommus" bindings are mutually exclusive, since
> > +  the restricted memory access model on Xen behaves as a kind of software 
> > IOMMU.
> I don't think that this last statement is necessary or fully accurate, so
> I would remove it.

ok, will remove


> Other than that, this looks good to me.

thank you


> > +properties:
> > +  xen,dev-domid:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      Should contain the ID of device's domain.
> Maybe better as:
> "The domid (domain ID) of the domain where the device (backend) is running"

ok, will change


> > +additionalProperties: true
> > +
> > +examples:
> > +  - |
> > +    virtio_block@3000 {
> > +            compatible = "virtio,mmio";
> > +            reg = <0x3000 0x100>;
> > +            interrupts = <41>;
> > +
> > +            /* The device is located in Xen domain with ID 1 */
> > +            xen,dev-domid = <1>;
> > +    };
> > --
> > 2.7.4
--
Regards,

Oleksandr Tyshchenko