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Tsirkin" , Christoph Hellwig References: <1650646263-22047-1-git-send-email-olekstysh@gmail.com> <1650646263-22047-5-git-send-email-olekstysh@gmail.com> From: Oleksandr Message-ID: Date: Tue, 3 May 2022 20:09:32 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 03.05.22 00:59, Rob Herring wrote: Hello Rob > On Fri, Apr 22, 2022 at 07:51:01PM +0300, Oleksandr Tyshchenko wrote: >> From: Oleksandr Tyshchenko >> >> 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 >> --- >> Changes RFC -> V1: >> - update commit subject/description and text in description >> - move to devicetree/bindings/arm/ >> --- >> .../devicetree/bindings/arm/xen,dev-domid.yaml | 37 ++++++++++++++++++++++ >> 1 file changed, 37 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..ef0f747 >> --- /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 the virtualized device (e.g. virtio) >> + >> +maintainers: >> + - Oleksandr Tyshchenko >> + >> +select: true > Do we really need to support this property everywhere? From my understanding - yes. As, I think, any device node describing virtulized device in the guest device tree can have this property.  Initially (in the RFC series) the "solution to restrict memory access using Xen grant mappings" was virtio-specific. Although the support of virtio is a primary target of this series, we decided to generalize this work and expand it to any device [1]. So the Xen grant mappings scheme (this property to be used for) can be theoretically used for any device emulated by the Xen backend. >> + >> +description: >> + This binding indicates that Xen grant mappings scheme needs to be enabled >> + for that device and 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. >> + >> +properties: >> + xen,dev-domid: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: >> + The domid (domain ID) of the domain where the device (backend) is running. >> + >> +additionalProperties: true >> + >> +examples: >> + - | >> + virtio_block@3000 { > virtio@3000 ok, will change > >> + compatible = "virtio,mmio"; >> + reg = <0x3000 0x100>; >> + interrupts = <41>; >> + >> + /* The device is located in Xen domain with ID 1 */ >> + xen,dev-domid = <1>; > This fails validation: > > Documentation/devicetree/bindings/arm/xen,dev-domid.example.dtb: virtio_block@3000: xen,dev-domid: [[1]] is not of type 'object' > From schema: /home/rob/proj/git/linux-dt/Documentation/devicetree/bindings/virtio/mmio.yaml Thank you for pointing this out, my fault, I haven't "properly" checked this before. I think, we need to remove "compatible = "virtio,mmio"; here diff --git a/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml b/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml index 2daa8aa..d2f2140 100644 --- a/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml +++ b/Documentation/devicetree/bindings/arm/xen,dev-domid.yaml @@ -28,7 +28,7 @@ additionalProperties: true  examples:    - |      virtio_block@3000 { -            compatible = "virtio,mmio"; +            /* ... */              reg = <0x3000 0x100>;              interrupts = <41>; > > The property has to be added to the virtio/mmio.yaml schema. If it is > not needed elsewhere, then *just* add the property there. As I described above, the property is not virtio specific and can be used for any virtualized device for which Xen grant mappings scheme needs to be enabled (xen-grant DMA-mapping layer). [1] https://lore.kernel.org/xen-devel/alpine.DEB.2.22.394.2204181202080.915916@ubuntu-linux-20-04-desktop/ > > Rob -- Regards, Oleksandr Tyshchenko