[PATCH 07/28] libxl: libxl__device_model_xs_path: Add emulator_id parameter

[Ian Jackson <ian.jackson@eu.citrix.com>]

We are going to want to talk to two different qemus for some domains.
This will involve a different xenstore path for the two qemus, so
libxl__device_model_xs_path will need to take a parameter to say which.

Most call sites will want to talk to the main (device model, `DM')
emulator.  So introduce that parameter now, currently always passing
EMUID_DM, which is defined in a dummy way that ensures the actual
argument is EMUID_DM.

No functional change.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
---
v6: Largely rewritten, but in some sense (at least conceptually)
    based on a similar concept in v5.
---
 tools/libxl/libxl_device.c      |    3 ++-
 tools/libxl/libxl_dm.c          |   11 ++++++-----
 tools/libxl/libxl_dom.c         |   12 +++++++-----
 tools/libxl/libxl_dom_suspend.c |    3 ++-
 tools/libxl/libxl_internal.c    |    4 +++-
 tools/libxl/libxl_internal.h    |    9 ++++++---
 tools/libxl/libxl_pci.c         |    4 ++--
 7 files changed, 28 insertions(+), 18 deletions(-)

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index 8bb5e93..22665e4 100644
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -1183,7 +1183,8 @@ int libxl__wait_for_device_model_deprecated(libxl__gc *gc,
     char *path;
     uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
 
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+    path = libxl__device_model_xs_path(gc, dm_domid, domid,
+                                       EMUID_DM, "/state");
     return libxl__xenstore_child_wait_deprecated(gc, domid,
                                      LIBXL_DEVICE_MODEL_START_TIMEOUT,
                                      "Device Model", path, state, spawning,
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 6f5fe45..ea82e11 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1558,7 +1558,7 @@ void libxl__spawn_stub_dm(libxl__egc *egc, libxl__stub_dm_spawn_state *sdss)
 retry_transaction:
     t = xs_transaction_start(ctx->xsh);
     const char *dmpath = libxl__device_model_xs_path(gc,
-            dm_domid, guest_domid, "");
+            dm_domid, guest_domid, EMUID_DM, "");
     xs_mkdir(ctx->xsh, t, dmpath);
     xs_set_permissions(ctx->xsh, t,
                        dmpath,
@@ -1724,7 +1724,7 @@ static void stubdom_pvqemu_cb(libxl__egc *egc,
                                   dm_domid, sdss->dm.guest_domid);
     sdss->xswait.path =
         libxl__device_model_xs_path(gc, dm_domid, sdss->dm.guest_domid,
-                                    "/state");
+                                    EMUID_DM, "/state");
     sdss->xswait.timeout_ms = LIBXL_STUBDOM_START_TIMEOUT * 1000;
     sdss->xswait.callback = stubdom_xswait_cb;
     rc = libxl__xswait_start(gc, &sdss->xswait);
@@ -1831,7 +1831,8 @@ void libxl__spawn_local_dm(libxl__egc *egc, libxl__dm_spawn_state *dmss)
         free(path);
     }
 
-    path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID, domid, "");
+    path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID,
+                                       domid, EMUID_DM, "");
     xs_mkdir(ctx->xsh, XBT_NULL, path);
 
     if (b_info->type == LIBXL_DOMAIN_TYPE_HVM &&
@@ -1886,7 +1887,7 @@ retry_transaction:
 
     spawn->what = GCSPRINTF("domain %d device model", domid);
     spawn->xspath = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID,
-                                                domid, "/state");
+                                                domid, EMUID_DM, "/state");
     spawn->timeout_ms = LIBXL_DEVICE_MODEL_START_TIMEOUT * 1000;
     spawn->pidpath = GCSPRINTF("%s/image/device-model-pid", dom_path);
     spawn->midproc_cb = libxl__spawn_record_pid;
@@ -2099,7 +2100,7 @@ out:
 int libxl__destroy_device_model(libxl__gc *gc, uint32_t domid)
 {
     char *path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID,
-                                             domid, "");
+                                             domid, EMUID_DM, "");
     if (!xs_rm(CTX->xsh, XBT_NULL, path))
         LOG(ERROR, "xs_rm failed for %s", path);
     /* We should try to destroy the device model anyway. */
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 47971a9..6ded9c1 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -1103,7 +1103,8 @@ int libxl__qemu_traditional_cmd(libxl__gc *gc, uint32_t domid,
 {
     char *path = NULL;
     uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
-    path = libxl__device_model_xs_path(gc, dm_domid, domid, "/command");
+    path = libxl__device_model_xs_path(gc, dm_domid,
+                                       domid, EMUID_DM, "/command");
     return libxl__xs_printf(gc, XBT_NULL, path, "%s", cmd);
 }
 
@@ -1134,7 +1135,8 @@ int libxl__restore_emulator_xenstore_data(libxl__domain_create_state *dcs,
 
     const uint32_t domid = dcs->guest_domid;
     const uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
-    const char *xs_root = libxl__device_model_xs_path(gc, dm_domid, domid, "");
+    const char *xs_root = libxl__device_model_xs_path(gc, dm_domid,
+                                                      domid, EMUID_DM, "");
 
     while (next < end) {
         key = next;
@@ -1225,9 +1227,9 @@ static void domain_suspend_switch_qemu_xen_traditional_logdirty
     if (!lds->cmd_path) {
         uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
         lds->cmd_path = libxl__device_model_xs_path(gc, dm_domid, domid,
-                                                    "/logdirty/cmd");
+                                              EMUID_DM, "/logdirty/cmd");
         lds->ret_path = libxl__device_model_xs_path(gc, dm_domid, domid,
-                                                    "/logdirty/ret");
+                                              EMUID_DM, "/logdirty/ret");
     }
     lds->cmd = enable ? "enable" : "disable";
 
@@ -1442,7 +1444,7 @@ int libxl__save_emulator_xenstore_data(libxl__domain_suspend_state *dss,
     const uint32_t domid = dss->domid;
     const uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
 
-    xs_root = libxl__device_model_xs_path(gc, dm_domid, domid, "");
+    xs_root = libxl__device_model_xs_path(gc, dm_domid, domid, EMUID_DM, "");
 
     entries = libxl__xs_directory(gc, 0, GCSPRINTF("%s/physmap", xs_root),
                                   &nr_entries);
diff --git a/tools/libxl/libxl_dom_suspend.c b/tools/libxl/libxl_dom_suspend.c
index 3313ad1..d25fb59 100644
--- a/tools/libxl/libxl_dom_suspend.c
+++ b/tools/libxl/libxl_dom_suspend.c
@@ -383,7 +383,8 @@ int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid)
     case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL: {
         uint32_t dm_domid = libxl_get_stubdom_id(CTX, domid);
 
-        path = libxl__device_model_xs_path(gc, dm_domid, domid, "/state");
+        path = libxl__device_model_xs_path(gc, dm_domid, domid,
+                                           EMUID_DM, "/state");
         state = libxl__xs_read(gc, XBT_NULL, path);
         if (state != NULL && !strcmp(state, "paused")) {
             libxl__qemu_traditional_cmd(gc, domid, "continue");
diff --git a/tools/libxl/libxl_internal.c b/tools/libxl/libxl_internal.c
index 328046b..ec93797 100644
--- a/tools/libxl/libxl_internal.c
+++ b/tools/libxl/libxl_internal.c
@@ -554,7 +554,9 @@ void libxl__update_domain_configuration(libxl__gc *gc,
 }
 
 char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
-                                  uint32_t domid, const char *format,  ...)
+                                  uint32_t domid,
+                                  struct dummy_qemu_emulator_id emuid,
+                                  const char *format,  ...)
 {
     char *s, *fmt;
     va_list ap;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index fd6ef61..ea56cda 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1955,9 +1955,12 @@ _hidden libxl__json_object *libxl__json_parse(libxl__gc *gc_opt, const char *s);
 _hidden int libxl__device_model_version_running(libxl__gc *gc, uint32_t domid);
   /* Return the system-wide default device model */
 _hidden libxl_device_model_version libxl__default_device_model(libxl__gc *gc);
-_hidden char *libxl__device_model_xs_path(libxl__gc *gc, uint32_t dm_domid,
-                                          uint32_t domid,
-                                          const char *format, ...) PRINTF_ATTRIBUTE(4, 5);
+
+static const struct dummy_qemu_emulator_id { int x; } EMUID_DM;
+_hidden char *libxl__device_model_xs_path(libxl__gc *gc,
+        uint32_t dm_domid,
+        uint32_t domid, struct dummy_qemu_emulator_id,
+        const char *format, ...) PRINTF_ATTRIBUTE(5, 6);
 
 /*
  * Calling context and GC for event-generating functions:
diff --git a/tools/libxl/libxl_pci.c b/tools/libxl/libxl_pci.c
index 2c7a2c6..86b8cf3 100644
--- a/tools/libxl/libxl_pci.c
+++ b/tools/libxl/libxl_pci.c
@@ -967,7 +967,7 @@ static int qemu_pci_add_xenstore(libxl__gc *gc, uint32_t domid,
     uint32_t dm_domid;
 
 #define DMPATH(suffix) \
-    libxl__device_model_xs_path(gc, dm_domid, domid, (suffix))
+    libxl__device_model_xs_path(gc, dm_domid, domid, EMUID_DM, (suffix))
 
     dm_domid = libxl_get_stubdom_id(CTX, domid);
     path = DMPATH("/state");
@@ -1313,7 +1313,7 @@ static int qemu_pci_remove_xenstore(libxl__gc *gc, uint32_t domid,
     dm_domid = libxl_get_stubdom_id(CTX, domid);
 
 #define DMPATH(suffix) \
-    libxl__device_model_xs_path(gc, dm_domid, domid, suffix)
+    libxl__device_model_xs_path(gc, dm_domid, domid, EMUID_DM, suffix)
 
     path = DMPATH("/state");
     state = libxl__xs_read(gc, XBT_NULL, path);
-- 
1.7.10.4