kvm: do not try to correct disk-related parameters

The user must be aware of any mistake he did. For example, he may lose
time by not understanding why the VM does not behave as expected or by
distorting measures in benchmarks.

The only legitimate reason to automatically fix a parameter is backward
compatibility, if a value is not valid anymore. But such fallback
should only be temporary. There's no such case recently.

At last, it increased maintenance by having to keep the lists of valid
values up-to-date.

About:

  -  if disk_info['io'] == 'native':
  -    additional_disk_options += ',cache.direct=on'

These lines are redundant when cache is none.

software/kvm/buildout.hash.cfg

@@ -19,7 +19,7 @@ md5sum = 0d34ff81779115bf899f7bc752877b70
 
 [template-kvm]
 filename = instance-kvm.cfg.jinja2
-md5sum = 854ec0f379a05246f5f3761fdb634c36
+md5sum = 4f71b7616b9f4a2f968e89326a237768
 
 [template-kvm-cluster]
 filename = instance-kvm-cluster.cfg.jinja2.in
@@ -55,7 +55,7 @@ md5sum = b7e87479a289f472b634a046b44b5257
 
 [template-kvm-run]
 filename = template/template-kvm-run.in
-md5sum = a8afeb2f80199368e291621576a80ca1
+md5sum = e7b9623eabe1bbd5233e0fbfde94a67c
 
 [template-kvm-controller]
 filename = template/kvm-controller-run.in

software/kvm/instance-kvm.cfg.jinja2

@@ -932,8 +932,8 @@ disk-format = qcow2
 disk-device-path =
 
 cpu-count = 1
-disk-cache = writeback
-disk-aio = native
+disk-cache =
+disk-aio =
 auto-ballooning = True
 machine-options =
 cpu-model = host

software/kvm/template/template-kvm-run.in

@@ -20,13 +20,10 @@ import json
 import ssl
 
 # XXX: give all of this through parameter, don't use this as template, but as module
-qemu_img_path = '{{ parameter_dict.get("qemu-img-path") }}'
-qemu_path = '{{ parameter_dict.get("qemu-path") }}'
-disk_size = '{{ parameter_dict.get("disk-size") }}'
-disk_type = '{{ parameter_dict.get("disk-type") }}'
-disk_format = '{{ parameter_dict.get("disk-format", "qcow2")}}'
-disk_format = disk_format \
-              if disk_format in ['qcow2', 'raw', 'vdi', 'vmdk', 'cloop', 'qed'] else 'qcow2'
+qemu_img_path = {{ repr(parameter_dict["qemu-img-path"]) }}
+qemu_path = {{ repr(parameter_dict["qemu-path"]) }}
+disk_size = {{ repr(parameter_dict["disk-size"]) }}
+disk_type = {{ repr(parameter_dict["disk-type"]) }}
 
 socket_path = '{{ parameter_dict.get("socket-path") }}'
 nbd_list = (('{{ parameter_dict.get("nbd-host") }}',
@@ -34,7 +31,6 @@ nbd_list = (('{{ parameter_dict.get("nbd-host") }}',
             ('{{ parameter_dict.get("nbd2-host") }}',
               {{ parameter_dict.get("nbd2-port") }}))
 default_cdrom_iso = '{{ parameter_dict.get("default-cdrom-iso") }}'
-disk_path = '{{ parameter_dict.get("disk-path") }}'
 
 virtual_hard_drive_url = '{{ parameter_dict.get("virtual-hard-drive-url") }}'.strip()
 virtual_hard_drive_md5sum = '{{ parameter_dict.get("virtual-hard-drive-md5sum") }}'.strip()
@@ -56,9 +52,7 @@ init_ram_size = {{ parameter_dict.get("init-ram-size") }}
 pid_file_path = '{{ parameter_dict.get("pid-file-path") }}'
 external_disk_number = {{ parameter_dict.get("external-disk-number") }}
 external_disk_size = {{ parameter_dict.get("external-disk-size") }}
-external_disk_format = '{{ parameter_dict.get("external-disk-format", "qcow2") }}'
-external_disk_format = external_disk_format \
-              if external_disk_format in ['qcow2', 'raw', 'vdi', 'vmdk', 'cloop', 'qed'] else 'qcow2'
+external_disk_format = {{ repr(parameter_dict["external-disk-format"]) }}
 disk_storage_dict = {}
 disk_storage_list = """{{ parameter_dict.get("disk-storage-list") }}""".split('\n')
 map_storage_list = []
@@ -70,11 +64,6 @@ cluster_doc_port = {{ parameter_dict.get("cluster-doc-port") }}
 url_check_certificate = '{{ parameter_dict.get("hard-drive-url-check-certificate", "true") }}'.lower()
 auto_ballooning = '{{ parameter_dict.get("auto-ballooning") }}' in ('true', 'True', '1')
 vm_name = '{{ parameter_dict.get("name") }}'
-disk_cache = '{{ parameter_dict.get("disk-cache", "writeback") }}'.strip()
-disk_cache = disk_cache if disk_cache in ["none", "writeback", "unsafe", 
-              "directsync", "writethrough"] else "writeback"
-disk_aio = '{{ parameter_dict.get("disk-aio", "threads") }}'.strip()
-disk_aio = disk_aio if disk_aio in ["threads", "native"] else "threads"
 
 # If a device (ie.: /dev/sdb) is provided, use it instead 
 # the disk_path with disk_format
@@ -84,16 +73,18 @@ for disk_device_path in '{{ parameter_dict.get("disk-device-path", "") }}'.split
     disk_info_list.append({
       'path': disk_device_path,
       'format': "raw",
-      'io': "native",
+      'aio': "native",
       'cache': "none"
     })
 
-if len(disk_info_list) == 0:
+if not disk_info_list:
   disk_info_list.append({
-    'path': disk_path,
-    'format': disk_format,
-    'io': disk_aio,
-    'cache': disk_cache,
+{%- for k in 'path', 'format', 'aio', 'cache' %}
+{%-   set v = parameter_dict['disk-' + k] %}
+{%-   if v %}
+    {{ repr(k) }}: {{ repr(v) }},
+{%-   endif %}
+{%- endfor %}
   })
 
 smp_count = {{ parameter_dict.get("smp-count") }}
@@ -312,14 +303,14 @@ kvm_argument_list = [qemu_path,
 for disk_info in disk_info_list:
   additional_disk_options = ''
 
-  if disk_info['io'] == 'native':
-    additional_disk_options += ',cache.direct=on'
   if disk_info['format'] == "raw":
     additional_disk_options += ',discard=on'
 
   kvm_argument_list.extend([
     '-drive',
-    'file=%s,if=%s,cache=%s,aio=%s%s' % ( disk_info['path'], disk_type, disk_info['cache'], disk_info['io'], additional_disk_options)
+    'file=%s,if=%s%s%s' % (
+      disk_info['path'], disk_type, additional_disk_options,
+      ''.join(',%s=%s' % x for x in disk_info.items() if x[0] != 'path'))
   ])
 
 rgx = re.compile('^[\w*\,][\=\d+\-\,\w]*$')