Re: [XEN][PATCH v12 16/20] xen/arm: Implement device tree node removal functionalities

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.09.2023 03:16, Vikram Garhwal wrote:
> --- a/xen/include/public/sysctl.h
> +++ b/xen/include/public/sysctl.h
> @@ -1185,6 +1185,25 @@ typedef struct xen_sysctl_cpu_policy 
> xen_sysctl_cpu_policy_t;
>  DEFINE_XEN_GUEST_HANDLE(xen_sysctl_cpu_policy_t);
>  #endif
>  
> +#if defined(__arm__) || defined (__aarch64__)

Nit (style): Please be consistent with defined().

> +/*
> + * XEN_SYSCTL_dt_overlay
> + * Performs addition/removal of device tree nodes under parent node using 
> dtbo.
> + * This does in three steps:
> + *  - Adds/Removes the nodes from dt_host.
> + *  - Adds/Removes IRQ permission for the nodes.
> + *  - Adds/Removes MMIO accesses.
> + */
> +struct xen_sysctl_dt_overlay {
> +    XEN_GUEST_HANDLE_64(const_void) overlay_fdt;  /* IN: overlay fdt. */
> +    uint32_t overlay_fdt_size;              /* IN: Overlay dtb size. */
> +#define XEN_SYSCTL_DT_OVERLAY_ADD                   1
> +#define XEN_SYSCTL_DT_OVERLAY_REMOVE                2
> +    uint8_t overlay_op;                     /* IN: Add or remove. */
> +    uint8_t pad[3];                         /* IN: Must be zero. */
> +};
> +#endif
> +
>  struct xen_sysctl {
>      uint32_t cmd;
>  #define XEN_SYSCTL_readconsole                    1
> @@ -1215,6 +1234,7 @@ struct xen_sysctl {
>  #define XEN_SYSCTL_livepatch_op                  27
>  /* #define XEN_SYSCTL_set_parameter              28 */
>  #define XEN_SYSCTL_get_cpu_policy                29
> +#define XEN_SYSCTL_dt_overlay                    30
>      uint32_t interface_version; /* XEN_SYSCTL_INTERFACE_VERSION */
>      union {
>          struct xen_sysctl_readconsole       readconsole;
> @@ -1245,6 +1265,10 @@ struct xen_sysctl {
>  #if defined(__i386__) || defined(__x86_64__)
>          struct xen_sysctl_cpu_policy        cpu_policy;
>  #endif
> +
> +#if defined(__arm__) || defined (__aarch64__)

Same here then.

While not to be done right here, ultimately I expect we want to
have some other way of specifying whether an arch wants DT-
specific sub-ops (here or elsewhere). As per the hyperlaunch
plans aiui even x86 may gain such support ...

Jan

> +        struct xen_sysctl_dt_overlay        dt_overlay;
> +#endif
>          uint8_t                             pad[128];
>      } u;
>  };