qemu: format 'ramfb' attribute for mediated devices

It's possible to use ramfb as the boot display of an assigned vgpu
device. This was introduced in 4b95738c, but unfortunately the attribute
was not formatted into the xml output for such a device. This patch
fixes that oversight and adds a xml2xml test to verify proper behavior.

https://bugzilla.redhat.com/show_bug.cgi?id=1847791Signed-off-by: NJonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>
Signed-off-by: NJán Tomko <jtomko@redhat.com>
Reviewed-by: NJán Tomko <jtomko@redhat.com>

src/conf/domain_conf.c

@@ -28343,6 +28343,9 @@ virDomainHostdevDefFormat(virBufferPtr buf,
             if (mdevsrc->display != VIR_TRISTATE_SWITCH_ABSENT)
                 virBufferAsprintf(buf, " display='%s'",
                                   virTristateSwitchTypeToString(mdevsrc->display));
+            if (mdevsrc->ramfb != VIR_TRISTATE_SWITCH_ABSENT)
+                virBufferAsprintf(buf, " ramfb='%s'",
+                                  virTristateSwitchTypeToString(mdevsrc->ramfb));
         }
 
     }

tests/qemuxml2xmloutdata/hostdev-mdev-display-ramfb.x86_64-latest.xml

+<domain type='qemu'>
+  <name>QEMUGuest2</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu mode='custom' match='exact' check='none'>
+    <model fallback='forbid'>qemu64</model>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i386</emulator>
+    <controller type='usb' index='0' model='piix3-uhci'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <graphics type='vnc' port='-1' autoport='yes'>
+      <listen type='address'/>
+    </graphics>
+    <video>
+      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
+    </video>
+    <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-pci' display='on' ramfb='on'>
+      <source>
+        <address uuid='53764d0e-85a0-42b4-af5c-2046b460b1dc'/>
+      </source>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </hostdev>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -529,6 +529,7 @@ mymain(void)
             QEMU_CAPS_VFIO_PCI_DISPLAY,
             QEMU_CAPS_DEVICE_VFIO_PCI,
             QEMU_CAPS_VNC);
+    DO_TEST_CAPS_LATEST("hostdev-mdev-display-ramfb");
     DO_TEST("pci-rom", NONE);
     DO_TEST("pci-rom-disabled", NONE);
     DO_TEST("pci-rom-disabled-invalid", NONE);