[Xen-devel] [PATCH 2/4] libxl: set the backend type to Qdisk for CDROM devices on DM HVM guests

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

This is needed because the cd-{insert/eject} functions are not prepared to
deal with blkback, which would be used by default if no backend was
specified.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl.c          | 24 +++++++++++++++++++-----
 tools/libxl/libxl_create.c   |  2 +-
 tools/libxl/libxl_internal.h |  3 ++-
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index d35fc33..9d785a4 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -2301,7 +2301,8 @@ int libxl_devid_to_device_vtpm(libxl_ctx *ctx,
 
 
/******************************************************************************/
 
-int libxl__device_disk_setdefault(libxl__gc *gc, libxl_device_disk *disk)
+int libxl__device_disk_setdefault(libxl__gc *gc, libxl_device_disk *disk,
+                                  uint32_t domid)
 {
     int rc;
 
@@ -2312,6 +2313,19 @@ int libxl__device_disk_setdefault(libxl__gc *gc, 
libxl_device_disk *disk)
     rc = libxl__resolve_domid(gc, disk->backend_domname, &disk->backend_domid);
     if (rc < 0) return rc;
 
+    /* Force Qdisk backend for CDROM devices of guests with a device model. */
+    if (disk->is_cdrom != 0 &&
+        libxl__domain_type(gc, domid) == LIBXL_DOMAIN_TYPE_HVM &&
+        libxl__device_model_version_running(gc, domid) !=
+        LIBXL_DEVICE_MODEL_VERSION_NONE) {
+        if (!(disk->backend == LIBXL_DISK_BACKEND_QDISK ||
+              disk->backend == LIBXL_DISK_BACKEND_UNKNOWN)) {
+            LOG(ERROR, "Backend for CD devices on HVM guests must be Qdisk");
+            return ERROR_FAIL;
+        }
+        disk->backend = LIBXL_DISK_BACKEND_QDISK;
+    }
+
     rc = libxl__device_disk_set_backend(gc, disk);
     return rc;
 }
@@ -2427,7 +2441,7 @@ static void device_disk_add(libxl__egc *egc, uint32_t 
domid,
             }
         }
 
-        rc = libxl__device_disk_setdefault(gc, disk);
+        rc = libxl__device_disk_setdefault(gc, disk, domid);
         if (rc) goto out;
 
         front = flexarray_make(gc, 16, 1);
@@ -2869,7 +2883,7 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid, 
libxl_device_disk *disk,
     disk_empty.vdev = libxl__strdup(NOGC, disk->vdev);
     disk_empty.pdev_path = libxl__strdup(NOGC, "");
     disk_empty.is_cdrom = 1;
-    libxl__device_disk_setdefault(gc, &disk_empty);
+    libxl__device_disk_setdefault(gc, &disk_empty, domid);
 
     libxl_domain_type type = libxl__domain_type(gc, domid);
     if (type == LIBXL_DOMAIN_TYPE_INVALID) {
@@ -2910,7 +2924,7 @@ int libxl_cdrom_insert(libxl_ctx *ctx, uint32_t domid, 
libxl_device_disk *disk,
         goto out;
     }
 
-    rc = libxl__device_disk_setdefault(gc, disk);
+    rc = libxl__device_disk_setdefault(gc, disk, domid);
     if (rc) goto out;
 
     if (!disk->pdev_path) {
@@ -3173,7 +3187,7 @@ void libxl__device_disk_local_initiate_attach(libxl__egc 
*egc,
             disk->script = libxl__strdup(gc, in_disk->script);
         disk->vdev = NULL;
         
-        rc = libxl__device_disk_setdefault(gc, disk);
+        rc = libxl__device_disk_setdefault(gc, disk, LIBXL_TOOLSTACK_DOMID);
         if (rc) goto out;
 
         libxl__prepare_ao_device(ao, &dls->aodev);
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 24f168b..1a57907 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -923,7 +923,7 @@ static void initiate_domain_create(libxl__egc *egc,
     store_libxl_entry(gc, domid, &d_config->b_info);
 
     for (i = 0; i < d_config->num_disks; i++) {
-        ret = libxl__device_disk_setdefault(gc, &d_config->disks[i]);
+        ret = libxl__device_disk_setdefault(gc, &d_config->disks[i], domid);
         if (ret) {
             LOG(ERROR, "Unable to set disk defaults for disk %d", i);
             goto error_out;
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 55896f8..47aca76 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1204,7 +1204,8 @@ _hidden int 
libxl__domain_create_info_setdefault(libxl__gc *gc,
 _hidden int libxl__domain_build_info_setdefault(libxl__gc *gc,
                                         libxl_domain_build_info *b_info);
 _hidden int libxl__device_disk_setdefault(libxl__gc *gc,
-                                          libxl_device_disk *disk);
+                                          libxl_device_disk *disk,
+                                          uint32_t domid);
 _hidden int libxl__device_nic_setdefault(libxl__gc *gc, libxl_device_nic *nic,
                                          uint32_t domid);
 _hidden int libxl__device_vtpm_setdefault(libxl__gc *gc, libxl_device_vtpm 
*vtpm);
-- 
2.6.4 (Apple Git-63)


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