Re: [PATCH v2 25/29] tools/xenstored: map stubdom interface

[Julien Grall <julien@xxxxxxx>]

Hi Juergen,

On 10/11/2023 16:08, Juergen Gross wrote:
> When running as stubdom, map the stubdom's Xenstore ring page in order
> to support using the 9pfs frontend.
>
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> ---
>   tools/xenstored/core.c   |  2 ++
>   tools/xenstored/domain.c | 27 ++++++++++++++++++++++++++-
>   tools/xenstored/domain.h |  1 +
>   3 files changed, 29 insertions(+), 1 deletion(-)
>
> diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c
> index b9ec50b34c..4a9d874f17 100644
> --- a/tools/xenstored/core.c
> +++ b/tools/xenstored/core.c
> @@ -2991,6 +2991,8 @@ int main(int argc, char *argv[])
>                 lu_read_state();
>   #endif
>   
> +	stubdom_init();
> +
>         check_store();
>   
>   	/* Get ready to listen to the tools. */
> diff --git a/tools/xenstored/domain.c b/tools/xenstored/domain.c
> index fa17f68618..162b87b460 100644
> --- a/tools/xenstored/domain.c
> +++ b/tools/xenstored/domain.c
> @@ -37,6 +37,10 @@
>   #include <xenctrl.h>
>   #include <xen/grant_table.h>
>   
> +#ifdef __MINIOS__
> +#include <mini-os/xenbus.h>
> +#endif
> +
>   static xc_interface **xc_handle;
>   xengnttab_handle **xgt_handle;
>   static evtchn_port_t virq_port;
> @@ -500,6 +504,11 @@ static void *map_interface(domid_t domid)
>         if (domid == xenbus_master_domid())
>                 return xenbus_map();
>   
> +#ifdef __MINIOS__
> +       if (domid == stub_domid)
> +               return xenstore_buf;
> +#endif
> +
>         return xengnttab_map_grant_ref(*xgt_handle, domid,
>                                        GNTTAB_RESERVED_XENSTORE,
>                                        PROT_READ|PROT_WRITE);
> @@ -509,7 +518,7 @@ static void unmap_interface(domid_t domid, void *interface)
>   {
>         if (domid == xenbus_master_domid())
>                 unmap_xenbus(interface);
> -       else
> +       else if (domid != stub_domid)
>                 xengnttab_unmap(*xgt_handle, interface, 1);
>   }
>   
> @@ -1214,6 +1223,22 @@ void dom0_init(void)
>         xenevtchn_notify(xce_handle, dom0->port);
>   }
>   
> +void stubdom_init(void)
> +{
> +#ifdef __MINIOS__
> +       struct domain *stubdom;
> +
> +       if (stub_domid < 0)
> +               return;
> +
> +       stubdom = introduce_domain(NULL, stub_domid, xenbus_evtchn, false);
> +       if (!stubdom)
> +               barf_perror("Failed to initialize stubdom");
> +
> +       xenevtchn_notify(xce_handle, stubdom->port);
If I compare to introduce_domain(), it is not entirely clear to me why 
the notification is done unconditionally here. Can you clarify?
> +#endif
> +}
> +
>   static unsigned int domhash_fn(const void *k)
>   {
>         return *(const unsigned int *)k;
> diff --git a/tools/xenstored/domain.h b/tools/xenstored/domain.h
> index 6c00540311..49c60c56bf 100644
> --- a/tools/xenstored/domain.h
> +++ b/tools/xenstored/domain.h
> @@ -85,6 +85,7 @@ int do_reset_watches(const void *ctx, struct connection *conn,
>   void domain_static_init(void);
>   void domain_init(int evtfd);
>   void dom0_init(void);
> +void stubdom_init(void);
>   void domain_deinit(void);
>   void ignore_connection(struct connection *conn, unsigned int err);
>   
Cheers,

--
Julien Grall