Re: [PATCH v6 5/7] xen/arm: Add XEN_DOMCTL_dt_overlay and device attachment to domains

[Julien Grall <julien@xxxxxxx>]

Hi Stefano,

On 24/05/2024 23:16, Stefano Stabellini wrote:
> From: Henry Wang <xin.wang2@xxxxxxx>
>
> In order to support the dynamic dtbo device assignment to a running
> VM, the add/remove of the DT overlay and the attach/detach of the
> device from the DT overlay should happen separately. Therefore,
> repurpose the existing XEN_SYSCTL_dt_overlay to only add the DT
> overlay to Xen device tree, instead of assigning the device to the
> hardware domain at the same time. It is OK to change the sysctl behavior
> as this feature is experimental so changing sysctl behavior and breaking
> compatibility is OK.
>
> Add the XEN_DOMCTL_dt_overlay with operations
> XEN_DOMCTL_DT_OVERLAY_ATTACH to do the device assignment to the domain.
>
> The hypervisor firstly checks the DT overlay passed from the toolstack
> is valid. Then the device nodes are retrieved from the overlay tracker
> based on the DT overlay. The attach of the device is implemented by
> mapping the IRQ and IOMMU resources. All devices in the overlay are
> assigned to a single domain.
>
> Also take the opportunity to make one coding style fix in sysctl.h.
> Introduce DT_OVERLAY_MAX_SIZE and use it to avoid repetitions of
> KB(500).
>
> xen,reg is to be used to handle non-1:1 mappings but it is currently
> unsupported. For now return errors for not-1:1 mapped domains.
>
> Signed-off-by: Henry Wang <xin.wang2@xxxxxxx>
> Signed-off-by: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
Acked-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall