Use existing nvram path in libvirt driver to support session daemon mode

When libvirtd is started as a non-root user it does not have access to
folder /var/lib/libvirt. By default, libvirtd in session daemon mode
creates a nvram file at path ~/.config/libvirt/qemu/nvram/\
[DOMAIN]_VARS[EXT] instead [0],[1].

Querying the nvram path in session daemon mode is difficult because
libvirtd does not expose it nor $HOME of the user that runs the daemon.
As a workaround, this change will let libvirtd create the nvram file
path if it has not been previously defined [2]. However, if it had been
defined earlier then the path will be changed to enforce regenerating
it from the template.

[0] 2b148748c2/src/qemu/qemu_conf.c (L203)
[1] 2b148748c2/src/qemu/qemu_firmware.c (L1124)
[2] 2b148748c2/src/qemu/qemu_firmware.c (L1065)

Change-Id: Id78101f5c1f5fdf4b365d2d270dbde8877b05dbf

sushy_tools/emulator/resources/systems/libvirtdriver.py

@@ -598,6 +598,11 @@ class LibvirtDriver(AbstractSystemsDriver):
                 boot_mode, os_arch)
             loader_path = None
 
+        nvram_element = os_element.find('nvram')
+        nvram_path = None
+        if nvram_element:
+            nvram_path = nvram_element.text
+
         # delete loader and nvram elements to rebuild from stratch
         for element in os_element.findall('loader'):
             os_element.remove(element)
@@ -617,16 +622,23 @@ class LibvirtDriver(AbstractSystemsDriver):
                 loader_element.set('secure', 'yes')
                 nvram_element.set('template', self.SECURE_BOOT_ENABLED_NVRAM)
             else:
-                nvram_suffix = '.fd'
+                nvram_suffix = '.nosecboot.fd'
                 loader_element.set('secure', 'no')
                 nvram_element.set('template', self.SECURE_BOOT_DISABLED_NVRAM)
 
             # force a different nvram path for secure vs not. This will ensure
             # it gets regenerated from the template when secure boot mode
             # changes
-            nvram_path = "/var/lib/libvirt/nvram-%s%s" % (identity,
-                                                          nvram_suffix)
-            nvram_element.text = nvram_path
+            if nvram_path:
+                nvram_file = os.path.basename(nvram_path)
+                if not nvram_file.endswith(nvram_suffix):
+                    nvram_file = nvram_file.\
+                        removesuffix('.secboot.fd').\
+                        removesuffix('.nosecboot.fd').\
+                        removesuffix('.fd') + nvram_suffix
+
+                nvram_element.text = os.path.join(os.path.dirname(nvram_path),
+                                                  nvram_file)
 
     def get_secure_boot(self, identity):
         """Get computer system secure boot state for UEFI boot mode.

sushy_tools/tests/unit/emulator/domain-q35_uefi.xml

@@ -7,7 +7,7 @@
   <os>
     <type arch="x86_64" machine="q35">hvm</type>
     <loader readonly="yes" type="pflash">/usr/share/OVMF/OVMF_CODE.fd</loader>
-    <nvram template="/usr/share/OVMF/OVMF_VARS.fd"/>
+    <nvram template="/usr/share/OVMF/OVMF_VARS.fd">/var/lib/libvirt/nvram/QEmu-fedora-i686_VARS.fd</nvram>
     <boot dev="disk"/>
   </os>
   <devices>

sushy_tools/tests/unit/emulator/domain-q35_uefi_secure.xml

@@ -7,7 +7,7 @@
   <os>
     <type arch="x86_64" machine="q35">hvm</type>
     <loader secure="yes" readonly="yes" type="pflash">/usr/share/OVMF/OVMF_CODE.secboot.fd</loader>
-    <nvram template="/usr/share/OVMF/OVMF_VARS.secboot.fd"/>
+    <nvram template="/usr/share/OVMF/OVMF_VARS.secboot.fd">/var/lib/libvirt/nvram/QEmu-fedora-i686_VARS.fd</nvram>
     <boot dev="disk"/>
   </os>
   <devices>

sushy_tools/tests/unit/emulator/resources/systems/test_libvirt.py

@@ -1203,8 +1203,8 @@ class LibvirtDriverTestCase(base.BaseTestCase):
                          loader_element.text)
         self.assertEqual('/usr/share/OVMF/OVMF_VARS.secboot.fd',
                          nvram_element.get('template'))
-        self.assertEqual('/var/lib/libvirt/nvram-%s.secboot.fd' %
-                         self.uuid, nvram_element.text)
+        self.assertEqual('/var/lib/libvirt/nvram/%s_VARS.secboot.fd' %
+                         self.name, nvram_element.text)
 
     @mock.patch('libvirt.open', autospec=True)
     @mock.patch('libvirt.openReadOnly', autospec=True)
@@ -1230,8 +1230,8 @@ class LibvirtDriverTestCase(base.BaseTestCase):
                          loader_element.text)
         self.assertEqual('/usr/share/OVMF/OVMF_VARS.fd',
                          nvram_element.get('template'))
-        self.assertEqual('/var/lib/libvirt/nvram-%s.fd' %
-                         self.uuid, nvram_element.text)
+        self.assertEqual('/var/lib/libvirt/nvram/%s_VARS.nosecboot.fd' %
+                         self.name, nvram_element.text)
 
     @mock.patch('libvirt.open', autospec=True)
     @mock.patch('libvirt.openReadOnly', autospec=True)