On 23.10.2024 15:10, Juergen Gross wrote:
> Add a new domctl sub-function to get data of a domain having changed
> state (this is needed by Xenstore).
>
> The returned state just contains the domid, the domain unique id,
> and some flags (existing, shutdown, dying).
>
> In order to enable Xenstore stubdom being built for multiple Xen
> versions, make this domctl stable. For stable domctls the
> interface_version is specific to the respective domctl op and it is an
> in/out parameter: On input the caller is specifying the desired version
> of the op, while on output the hypervisor will return the used version
> (this will be at max the caller supplied version, but might be lower in
> case the hypervisor doesn't support this version).
>
> Signed-off-by: Juergen Gross <[email protected]>
> ---
> V1:
> - use a domctl subop for the new interface (Jan Beulich)
Just as a preliminary reply: With Andrew's stabilization plans I'm not
sure this, in particular including ...
> @@ -1236,7 +1237,37 @@ struct xen_domctl_dt_overlay {
> };
> #endif
>
> +/*
> + * XEN_DOMCTL_get_domain_state (stable interface)
> + *
> + * Get state information of a domain.
> + *
> + * In case domain is DOMID_INVALID, return information about a domain having
> + * changed state and reset the state change indicator for that domain. This
> + * function is usable only by a domain having registered the VIRQ_DOM_EXC
> + * event (normally Xenstore).
> + *
> + * Supported interface versions: 0x00000000
> + */
> +#define XEN_DOMCTL_GETDOMSTATE_VERS_MAX 0
> +struct xen_domctl_get_domain_state {
> + domid_t domid;
> + uint16_t state;
> +#define XEN_DOMCTL_GETDOMSTATE_STATE_EXIST 0x0001 /* Domain is
> existing. */
> +#define XEN_DOMCTL_GETDOMSTATE_STATE_SHUTDOWN 0x0002 /* Shutdown finished.
> */
> +#define XEN_DOMCTL_GETDOMSTATE_STATE_DYING 0x0004 /* Domain dying. */
> + uint32_t pad1; /* Returned as 0. */
> + uint64_t unique_id; /* Unique domain identifier. */
> + uint64_t pad2[6]; /* Returned as 0. */
> +};
> +
> struct xen_domctl {
> +/*
> + * Stable domctl ops:
> + * interface_version is per cmd, hypervisor can support multiple versions
> + * and will return used version (at max caller supplied value) in
> + * interface_version on return.
> + */
... this (ab)use of the interface version, is the way to go. I think
we want a brand new hypercall, with stability just like most other
hypercalls have it. Backwards-incompatible interface changes then
simply aren't allowed (as in: require a new sub-op instead).
Jan
