[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH V2 5/7] dt-bindings: Add xen,dev-domid property description for xen-grant DMA ops
On 18.05.22 17:32, Arnd Bergmann wrote: Hello Arnd On Sat, May 7, 2022 at 7:19 PM Oleksandr Tyshchenko <olekstysh@xxxxxxxxx> wrote: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 + required: - compatible - regSorry for joining the discussion late. Have you considered using the generic iommu binding here instead of a custom property? I have to admit - no, I haven't. I was thinking that Xen specific feature should be communicated using Xen specific DT property. This would mean having a device node for the grant-table mechanism that can be referred to using the 'iommus' phandle property, with the domid as an additional argument. I assume, you are speaking about something like the following? xen_dummy_iommu { compatible = "xen,dummy-iommu"; #iommu-cells = <1>; }; virtio@3000 { compatible = "virtio,mmio"; reg = <0x3000 0x100>; interrupts = <41>; /* The device is located in Xen domain with ID 1 */ iommus = <&xen_dummy_iommu 1>; }; It does not quite fit the model that Linux currently uses for iommus, as that has an allocator for dma_addr_t space yes (# 3/7 adds grant-table based allocator) , but it would think it's conceptually close enough that it makes sense for the binding. Interesting idea. I am wondering, do we need an extra actions for this to work in Linux guest (dummy IOMMU driver, etc)? Arnd -- Regards, Oleksandr Tyshchenko
|
![]() |
Lists.xenproject.org is hosted with RackSpace, monitoring our |