[v2] libxl: devd: Spawn QEMU for 9pfs

Commit Message

Jason Andryuk April 7, 2024, 8:58 p.m. UTC

Add support for xl devd to support 9pfs in a domU.  devd need to spawn a
pvqemu for the domain to service 9pfs as well as qdisk backends.  Rename
num_qdisks to pvqemu_refcnt to be more generic.

Keep the qdisk-backend-pid xenstore key as well as the disk-%u log file.
They are externally visible, so the might be used by other tooling.

Signed-off-by: Jason Andryuk <[e-mail]>
Signed-off-by: Jason Andryuk <[e-mail]>
---
v2:
Retain xenstore qdisk-backend-pid and qdisk-%u logfile
---
 tools/libs/light/libxl_device.c   | 22 ++++++++++++----------
 tools/libs/light/libxl_dm.c       |  5 +++--
 tools/libs/light/libxl_internal.h |  4 ++--
 3 files changed, 17 insertions(+), 14 deletions(-)

Comments

Anthony PERARD April 9, 2024, 10:36 a.m. UTC | #1

On Sun, Apr 07, 2024 at 04:58:09PM -0400, Jason Andryuk wrote:
> Add support for xl devd to support 9pfs in a domU.  devd need to spawn a
> pvqemu for the domain to service 9pfs as well as qdisk backends.  Rename
> num_qdisks to pvqemu_refcnt to be more generic.
> 
> Keep the qdisk-backend-pid xenstore key as well as the disk-%u log file.
> They are externally visible, so the might be used by other tooling.

nit:                              ^^^ they

> 
> Signed-off-by: Jason Andryuk <[e-mail]>
> Signed-off-by: Jason Andryuk <[e-mail]>
> ---
> v2:
> Retain xenstore qdisk-backend-pid and qdisk-%u logfile

Patch looks fine otherwise:
Reviewed-by: Anthony PERARD <[e-mail]>

Thanks,

Patch

diff --git a/tools/libs/light/libxl_device.c b/tools/libs/light/libxl_device.c
index 6f0100d05e..a3d9f6f7df 100644
--- a/tools/libs/light/libxl_device.c
+++ b/tools/libs/light/libxl_device.c
@@ -1524,12 +1524,12 @@  static void device_complete(libxl__egc *egc, libxl__ao_device *aodev)
     libxl__nested_ao_free(aodev->ao);
 }
 
-static void qdisk_spawn_outcome(libxl__egc *egc, libxl__dm_spawn_state *dmss,
-                                int rc)
+static void qemu_xenpv_spawn_outcome(libxl__egc *egc,
+                                     libxl__dm_spawn_state *dmss, int rc)
 {
     STATE_AO_GC(dmss->spawn.ao);
 
-    LOGD(DEBUG, dmss->guest_domid, "qdisk backend spawn %s",
+    LOGD(DEBUG, dmss->guest_domid, "qemu xenpv backend spawn %s",
                 rc ? "failed" : "succeed");
 
     libxl__nested_ao_free(dmss->spawn.ao);
@@ -1552,7 +1552,7 @@  typedef struct libxl__ddomain_device {
  */
 typedef struct libxl__ddomain_guest {
     uint32_t domid;
-    int num_qdisks;
+    int pvqemu_refcnt;
     XEN_SLIST_HEAD(, struct libxl__ddomain_device) devices;
     XEN_SLIST_ENTRY(struct libxl__ddomain_guest) next;
 } libxl__ddomain_guest;
@@ -1646,15 +1646,16 @@  static int add_device(libxl__egc *egc, libxl__ao *ao,
 
     switch(dev->backend_kind) {
     case LIBXL__DEVICE_KIND_QDISK:
-        if (dguest->num_qdisks == 0) {
+    case LIBXL__DEVICE_KIND_9PFS:
+        if (dguest->pvqemu_refcnt == 0) {
             GCNEW(dmss);
             dmss->guest_domid = dev->domid;
             dmss->spawn.ao = ao;
-            dmss->callback = qdisk_spawn_outcome;
+            dmss->callback = qemu_xenpv_spawn_outcome;
 
-            libxl__spawn_qdisk_backend(egc, dmss);
+            libxl__spawn_qemu_xenpv_backend(egc, dmss);
         }
-        dguest->num_qdisks++;
+        dguest->pvqemu_refcnt++;
         break;
     default:
         GCNEW(aodev);
@@ -1685,8 +1686,9 @@  static int remove_device(libxl__egc *egc, libxl__ao *ao,
 
     switch(ddev->dev->backend_kind) {
     case LIBXL__DEVICE_KIND_QDISK:
-        if (--dguest->num_qdisks == 0) {
-            rc = libxl__destroy_qdisk_backend(gc, dev->domid);
+    case LIBXL__DEVICE_KIND_9PFS:
+        if (--dguest->pvqemu_refcnt == 0) {
+            rc = libxl__destroy_qemu_xenpv_backend(gc, dev->domid);
             if (rc)
                 goto out;
         }
diff --git a/tools/libs/light/libxl_dm.c b/tools/libs/light/libxl_dm.c
index 1a24e7961a..ff8ddeec9a 100644
--- a/tools/libs/light/libxl_dm.c
+++ b/tools/libs/light/libxl_dm.c
@@ -3380,7 +3380,8 @@  static void device_model_postconfig_done(libxl__egc *egc,
     dmss->callback(egc, dmss, rc);
 }
 
-void libxl__spawn_qdisk_backend(libxl__egc *egc, libxl__dm_spawn_state *dmss)
+void libxl__spawn_qemu_xenpv_backend(libxl__egc *egc,
+                                     libxl__dm_spawn_state *dmss)
 {
     STATE_AO_GC(dmss->spawn.ao);
     flexarray_t *dm_args, *dm_envs;
@@ -3470,7 +3471,7 @@  static int kill_device_model(libxl__gc *gc, const char *xs_path_pid)
 }
 
 /* Helper to destroy a Qdisk backend */
-int libxl__destroy_qdisk_backend(libxl__gc *gc, uint32_t domid)
+int libxl__destroy_qemu_xenpv_backend(libxl__gc *gc, uint32_t domid)
 {
     char *pid_path;
     int rc;
diff --git a/tools/libs/light/libxl_internal.h b/tools/libs/light/libxl_internal.h
index 094d0df9b1..dda3d15087 100644
--- a/tools/libs/light/libxl_internal.h
+++ b/tools/libs/light/libxl_internal.h
@@ -4196,9 +4196,9 @@  _hidden char *libxl__stub_dm_name(libxl__gc *gc, const char * guest_name);
 
 /* Qdisk backend launch helpers */
 
-_hidden void libxl__spawn_qdisk_backend(libxl__egc *egc,
+_hidden void libxl__spawn_qemu_xenpv_backend(libxl__egc *egc,
                                         libxl__dm_spawn_state *dmss);
-_hidden int libxl__destroy_qdisk_backend(libxl__gc *gc, uint32_t domid);
+_hidden int libxl__destroy_qemu_xenpv_backend(libxl__gc *gc, uint32_t domid);
 
 /*----- Domain creation -----*/