[PATCH v4 07/12] tools/xenstored: Auto-introduce domains

[Jason Andryuk <jason.andryuk@xxxxxxx>]

Replace dom0_init() with init_domains() which uses libxenmanage to
iterate through all existing domains, storing them in a list.  The xenstore
domain is introduced first, and then all the other domains are
introduced.  The xenstore domain needs to be introduced first to setup
structures needed for firing watches.

dom0_domid is updated with the xenstore domain, since it really
indicates the local domain.

priv_domid is set to the control domain.  This makes it limited to a
single domain.

These features let xenstore automatically connect any existing domains,
which means it doesn't need to be done manually from init-dom0less.

For a legacy dom0, the result should be unchanged.

For a late xenstore stubdom it should also be the same, but priv_domid
would be set automatically to control domain (which default to 0
normally).

Always signal the event channel for initial domains.  This gets dom0 (a
local xenstored domain) to connect.

Also always write XENSTORE_CONNECTED since we know we are connected at
this point.

To support ARM dom0less domains with xen,enhanced = "no-xenstore" a
failed introduce_domain() becomes non-fatal.  Normally,
HVM_PARAM_STORE_EVTHCN is used to identify .

Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>
---
I noticed domain_conn_reset() isn't called for the stubdom, so I added
the ifdef to special case it.  I haven't tested with a stubdom yet, and
I wanted to be conservative.  Ideally it would be dropped - the issue
would be if the stubdom queues requests before xenstore is in service.
---
 tools/xenstored/core.c   |  2 +-
 tools/xenstored/domain.c | 83 ++++++++++++++++++++++++++++------------
 tools/xenstored/domain.h |  2 +-
 3 files changed, 61 insertions(+), 26 deletions(-)

diff --git a/tools/xenstored/core.c b/tools/xenstored/core.c
index 37e4dd5a5b..c2f8d20211 100644
--- a/tools/xenstored/core.c
+++ b/tools/xenstored/core.c
@@ -2757,7 +2757,7 @@ int main(int argc, char *argv[])
        /* Listen to hypervisor. */
        if (!live_update) {
                domain_init(-1);
-               dom0_init();
+               init_domains();
        }
 
        /* redirect to /dev/null now we're ready to accept connections */
diff --git a/tools/xenstored/domain.c b/tools/xenstored/domain.c
index 1c52254ba8..e9e45ed8e8 100644
--- a/tools/xenstored/domain.c
+++ b/tools/xenstored/domain.c
@@ -1280,41 +1280,76 @@ evtchn_port_t get_domain_evtchn(domid_t domid)
        return 0;
 }
 
-void dom0_init(void)
+void init_domains(void)
 {
-       evtchn_port_t port;
-       struct domain *dom0;
+       unsigned int *domids = NULL;
+       unsigned int nr_domids = 0;
+       unsigned int domid;
+       unsigned int state;
+       unsigned int caps;
+       uint64_t unique_id;
+       int introduce_count = 0;
+
+       while (!xenmanage_poll_changed_domain(xm_handle, &domid, &state, &caps,
+                                             &unique_id)) {
+               nr_domids++;
+               domids = realloc(domids, nr_domids * sizeof(*domids));
+               if (!domids)
+                       barf_perror("Failed to reallocate domids");
+
+               domids[nr_domids - 1] = domid;
+
+               if (caps & XENMANAGE_GETDOMSTATE_CAP_XENSTORE) {
+                       memmove(&domids[1], domids, (nr_domids - 1) * 
sizeof(*domids));
+                       /*
+                        * Local domid must be first to setup structures for
+                        * firing the special watches.
+                        */
+                       domids[0] = domid;
+                       dom0_domid = domid;
+               }
 
-       port = get_domain_evtchn(xenbus_master_domid());
-       if (port == -1)
-               barf_perror("Failed to initialize dom0 port");
+               if (caps & XENMANAGE_GETDOMSTATE_CAP_CONTROL)
+                       priv_domid = domid;
+       }
 
-       dom0 = introduce_domain(NULL, xenbus_master_domid(), port, false);
-       if (!dom0)
-               barf_perror("Failed to initialize dom0");
+       for (unsigned int i = 0; i < nr_domids; i++) {
+               evtchn_port_t port;
+               struct domain *domain;
+               domid = domids[i];
 
-       xenevtchn_notify(xce_handle, dom0->port);
-}
+               port = get_domain_evtchn(domid);
+               if (port == -1)
+                       barf_perror("Failed to initialize dom%u port", domid);
+
+               domain = introduce_domain(NULL, domid, port, false);
+               if (!domain) {
+                       xprintf("Could not initialize dom%u", domid);
+                       continue;
+               }
+               introduce_count++;
 
-void stubdom_init(void)
-{
 #ifdef __MINIOS__
-       struct domain *stubdom;
-       evtchn_port_t port;
+               if (domid != stub_domid)
+#endif
+                       domain_conn_reset(domain);
 
-       if (stub_domid < 0)
-               return;
+               if (domain->interface)
+                       domain->interface->connection = XENSTORE_CONNECTED;
 
-       port = get_domain_evtchn(stub_domid);
-       if (port == -1)
-               barf_perror("Failed to initialize dom0 port");
+               /* Notify the domain that xenstore is available */
+               xenevtchn_notify(xce_handle, domain->port);
+       }
 
-       stubdom = introduce_domain(NULL, stub_domid, port, false);
-       if (!stubdom)
-               barf_perror("Failed to initialize stubdom");
+       free(domids);
 
-       xenevtchn_notify(xce_handle, stubdom->port);
+       if (introduce_count == 0)
+               barf("Did not initialize any domains");
+}
 
+void stubdom_init(void)
+{
+#ifdef __MINIOS__
        mount_9pfs();
 #endif
 }
diff --git a/tools/xenstored/domain.h b/tools/xenstored/domain.h
index 844ac11510..6a78f06935 100644
--- a/tools/xenstored/domain.h
+++ b/tools/xenstored/domain.h
@@ -84,7 +84,7 @@ int do_reset_watches(const void *ctx, struct connection *conn,
 
 void domain_early_init(void);
 void domain_init(int evtfd);
-void dom0_init(void);
+void init_domains(void);
 void stubdom_init(void);
 void domain_deinit(void);
 void ignore_connection(struct connection *conn, unsigned int err);
-- 
2.50.1