When running as stubdom, map the stubdom's Xenstore ring page in order
to support using the 9pfs frontend.

Use the same pattern as in dom0_init() when running as daemon in dom0
(introduce the own domain, then send an event to the client side to
signal Xenstore is ready to communicate).

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jason Andryuk <jandryuk@gmail.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
---
 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 3bf2ec7734..48fc787ac1 100644
--- a/tools/xenstored/core.c
+++ b/tools/xenstored/core.c
@@ -2767,6 +2767,8 @@ 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 621b415088..1a7d5e9756 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);
+#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 224c4c23e2..844ac11510 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_early_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);
 
-- 
2.35.3