Re: [PATCH 03/15] xen/arm: Always enable IOMMU

[Julien Grall <julien@xxxxxxx>]

Hi Henry,

On 24/04/2024 04:34, Henry Wang wrote:
> From: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
>
> For overlay with iommu functionality to work with running VMs, we need to enable
> IOMMU by default for the domains.
>
> Signed-off-by: Vikram Garhwal <fnu.vikram@xxxxxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>
> Signed-off-by: Henry Wang <xin.wang2@xxxxxxx>
> ---
>   xen/arch/arm/dom0less-build.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
> index fb63ec6fd1..2d1fd1e214 100644
> --- a/xen/arch/arm/dom0less-build.c
> +++ b/xen/arch/arm/dom0less-build.c
> @@ -894,7 +894,8 @@ void __init create_domUs(void)
>               panic("Missing property 'cpus' for domain %s\n",
>                     dt_node_name(node));
>   
> -        if ( dt_find_compatible_node(node, NULL, "multiboot,device-tree") &&
> +        if ( (IS_ENABLED(CONFIG_OVERLAY_DTB) ||
Similar to the first patch, building Xen with the DTB overlay doesn't 
mean the user will want to use it (think of distros that may want to 
provide a generic Xen).
Instead, we should introduce a new DT property "passthrough" that would 
indicate whether the IOMMU should be used.
To be futureproof, I would match the values used by xl.cfg (see 
docs/man/xl.cfg.5.pod.in).
> +              dt_find_compatible_node(node, NULL, "multiboot,device-tree")) &&
>                iommu_enabled )
>               d_cfg.flags |= XEN_DOMCTL_CDF_iommu;
>   
Cheers,

--
Julien Grall