Re: [RFC PATCH v3 1/7] xen/arm: add generic SCI subsystem

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.03.2025 12:16, Grygorii Strashko wrote:
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -526,6 +526,12 @@ S:       Supported
>  F:   xen/arch/arm/include/asm/tee/
>  F:   xen/arch/arm/tee/
>  
> +SCI MEDIATORS
> +M:   Oleksii Moisieiev <oleksii_moisieiev@xxxxxxxx>
> +S:   Supported
> +F:   xen/arch/arm/sci
> +F:   xen/include/asm-arm/sci
> +
>  TOOLSTACK
>  M:   Anthony PERARD <anthony.perard@xxxxxxxxxx>
>  S:   Supported

Please can you respect alphabetical sorting in this file?

> @@ -851,6 +852,18 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) 
> u_domctl)
>      case XEN_DOMCTL_deassign_device:
>      case XEN_DOMCTL_get_device_group:
>          ret = iommu_do_domctl(op, d, u_domctl);
> +
> +        if ( ret >= 0 || (ret == -EOPNOTSUPP) || (ret == -ENODEV) )
> +        {
> +            /*
> +             * TODO: RFC
> +             * This change will allow to pass DT nodes/devices to
> +             * XEN_DOMCTL_assign_device OP using xl.cfg:"dtdev" property even
> +             * if those DT nodes/devices even are not behind IOMMU (or IOMMU
> +             * is disabled) without failure.
> +             */
> +            ret = sci_do_domctl(op, d, u_domctl);
> +        }
>          break;

Despite the comment I fear I don't understand what you're trying to do here.
In any event you may not clobber the original "ret", if all you do is some
"add-on".

> --- a/xen/include/asm-generic/device.h
> +++ b/xen/include/asm-generic/device.h
> @@ -18,6 +18,7 @@ enum device_class
>      DEVICE_IOMMU,
>      DEVICE_INTERRUPT_CONTROLLER,
>      DEVICE_PCI_HOSTBRIDGE,
> +    DEVICE_ARM_SCI,
>      /* Use for error */
>      DEVICE_UNKNOWN,

This is a generic header - I don't see how anything arch-specific could
validly end up here.

> --- a/xen/include/public/arch-arm.h
> +++ b/xen/include/public/arch-arm.h
> @@ -327,6 +327,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
>  #define XEN_DOMCTL_CONFIG_TEE_OPTEE     1
>  #define XEN_DOMCTL_CONFIG_TEE_FFA       2
>  
> +#define XEN_DOMCTL_CONFIG_ARM_SCI_NONE      0
> +
>  struct xen_arch_domainconfig {
>      /* IN/OUT */
>      uint8_t gic_version;
> @@ -350,6 +352,8 @@ struct xen_arch_domainconfig {
>       *
>       */
>      uint32_t clock_frequency;
> +    /* IN */
> +    uint8_t arm_sci_type;
>  };

You're not re-using a pre-existing padding field, so I don't see how you
can get away without bumping XEN_DOMCTL_INTERFACE_VERSION.

Jan