| Message ID | 20181012145917.6840-2-jean-philippe.brucker@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
| Series | Add virtio-iommu driver | expand |
On Fri, Oct 12, 2018 at 03:59:11PM +0100, Jean-Philippe Brucker wrote: > The nature of a virtio-mmio node is discovered by the virtio driver at > probe time. However the DMA relation between devices must be described > statically. When a virtio-mmio node is a virtio-iommu device, it needs an > "#iommu-cells" property as specified by bindings/iommu/iommu.txt. > > Otherwise, the virtio-mmio device may perform DMA through an IOMMU, which > requires an "iommus" property. Describe these requirements in the > device-tree bindings documentation. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> > --- > .../devicetree/bindings/virtio/mmio.txt | 30 +++++++++++++++++++ > 1 file changed, 30 insertions(+) One nit, otherwise, Reviewed-by: Rob Herring <robh@kernel.org> > > diff --git a/Documentation/devicetree/bindings/virtio/mmio.txt b/Documentation/devicetree/bindings/virtio/mmio.txt > index 5069c1b8e193..748595473b36 100644 > --- a/Documentation/devicetree/bindings/virtio/mmio.txt > +++ b/Documentation/devicetree/bindings/virtio/mmio.txt > @@ -8,10 +8,40 @@ Required properties: > - reg: control registers base address and size including configuration space > - interrupts: interrupt generated by the device > > +Required properties for virtio-iommu: > + > +- #iommu-cells: When the node corresponds to a virtio-iommu device, it is > + linked to DMA masters using the "iommus" or "iommu-map" > + properties [1][2]. #iommu-cells specifies the size of the > + "iommus" property. For virtio-iommu #iommu-cells must be > + 1, each cell describing a single endpoint ID. > + > +Optional properties: > + > +- iommus: If the device accesses memory through an IOMMU, it should > + have an "iommus" property [1]. Since virtio-iommu itself > + does not access memory through an IOMMU, the "virtio,mmio" > + node cannot have both an "#iommu-cells" and an "iommus" > + property. > + > Example: > > virtio_block@3000 { > compatible = "virtio,mmio"; > reg = <0x3000 0x100>; > interrupts = <41>; > + > + /* Device has endpoint ID 23 */ > + iommus = <&viommu 23> > } > + > + viommu: virtio_iommu@3100 { iommu@3100 > + compatible = "virtio,mmio"; > + reg = <0x3100 0x100>; > + interrupts = <42>; > + > + #iommu-cells = <1> > + } > + > +[1] Documentation/devicetree/bindings/iommu/iommu.txt > +[2] Documentation/devicetree/bindings/pci/pci-iommu.txt > -- > 2.19.1 >
Hi Jean, On 10/12/18 4:59 PM, Jean-Philippe Brucker wrote: > The nature of a virtio-mmio node is discovered by the virtio driver at > probe time. However the DMA relation between devices must be described > statically. When a virtio-mmio node is a virtio-iommu device, it needs an > "#iommu-cells" property as specified by bindings/iommu/iommu.txt. > > Otherwise, the virtio-mmio device may perform DMA through an IOMMU, which > requires an "iommus" property. Describe these requirements in the > device-tree bindings documentation. > > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> > --- > .../devicetree/bindings/virtio/mmio.txt | 30 +++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/Documentation/devicetree/bindings/virtio/mmio.txt b/Documentation/devicetree/bindings/virtio/mmio.txt > index 5069c1b8e193..748595473b36 100644 > --- a/Documentation/devicetree/bindings/virtio/mmio.txt > +++ b/Documentation/devicetree/bindings/virtio/mmio.txt > @@ -8,10 +8,40 @@ Required properties: > - reg: control registers base address and size including configuration space > - interrupts: interrupt generated by the device > > +Required properties for virtio-iommu: > + > +- #iommu-cells: When the node corresponds to a virtio-iommu device, it is > + linked to DMA masters using the "iommus" or "iommu-map" > + properties [1][2]. #iommu-cells specifies the size of the > + "iommus" property. For virtio-iommu #iommu-cells must be > + 1, each cell describing a single endpoint ID. > + > +Optional properties: > + > +- iommus: If the device accesses memory through an IOMMU, it should > + have an "iommus" property [1]. Since virtio-iommu itself > + does not access memory through an IOMMU, the "virtio,mmio" > + node cannot have both an "#iommu-cells" and an "iommus" > + property. > + > Example: > > virtio_block@3000 { > compatible = "virtio,mmio"; > reg = <0x3000 0x100>; > interrupts = <41>; > + > + /* Device has endpoint ID 23 */ > + iommus = <&viommu 23> > } > + > + viommu: virtio_iommu@3100 { > + compatible = "virtio,mmio"; > + reg = <0x3100 0x100>; > + interrupts = <42>; > + > + #iommu-cells = <1> > + } > + > +[1] Documentation/devicetree/bindings/iommu/iommu.txt > +[2] Documentation/devicetree/bindings/pci/pci-iommu.txt > Reviewed-by: Eric Auger <eric.auger@redhat.com> Thanks Eric
diff --git a/Documentation/devicetree/bindings/virtio/mmio.txt b/Documentation/devicetree/bindings/virtio/mmio.txt index 5069c1b8e193..748595473b36 100644 --- a/Documentation/devicetree/bindings/virtio/mmio.txt +++ b/Documentation/devicetree/bindings/virtio/mmio.txt @@ -8,10 +8,40 @@ Required properties: - reg: control registers base address and size including configuration space - interrupts: interrupt generated by the device +Required properties for virtio-iommu: + +- #iommu-cells: When the node corresponds to a virtio-iommu device, it is + linked to DMA masters using the "iommus" or "iommu-map" + properties [1][2]. #iommu-cells specifies the size of the + "iommus" property. For virtio-iommu #iommu-cells must be + 1, each cell describing a single endpoint ID. + +Optional properties: + +- iommus: If the device accesses memory through an IOMMU, it should + have an "iommus" property [1]. Since virtio-iommu itself + does not access memory through an IOMMU, the "virtio,mmio" + node cannot have both an "#iommu-cells" and an "iommus" + property. + Example: virtio_block@3000 { compatible = "virtio,mmio"; reg = <0x3000 0x100>; interrupts = <41>; + + /* Device has endpoint ID 23 */ + iommus = <&viommu 23> } + + viommu: virtio_iommu@3100 { + compatible = "virtio,mmio"; + reg = <0x3100 0x100>; + interrupts = <42>; + + #iommu-cells = <1> + } + +[1] Documentation/devicetree/bindings/iommu/iommu.txt +[2] Documentation/devicetree/bindings/pci/pci-iommu.txt
The nature of a virtio-mmio node is discovered by the virtio driver at probe time. However the DMA relation between devices must be described statically. When a virtio-mmio node is a virtio-iommu device, it needs an "#iommu-cells" property as specified by bindings/iommu/iommu.txt. Otherwise, the virtio-mmio device may perform DMA through an IOMMU, which requires an "iommus" property. Describe these requirements in the device-tree bindings documentation. Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com> --- .../devicetree/bindings/virtio/mmio.txt | 30 +++++++++++++++++++ 1 file changed, 30 insertions(+)