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

[Juergen Gross <jgross@xxxxxxxx>]

On 13.11.23 23:04, Julien Grall wrote:
> 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?
There is no reason to do it conditionally, as we can be sure the event channel
is existing and the ring page is accessible.


Juergen

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