conf: Introduce new video type 'none'

Historically, we've always enabled an emulated video device every time we
see that graphics should be supported with a guest. With the appearance
of mediated devices which can support QEMU's vfio-display capability,
users might want to use such a device as the only video device.
Therefore introduce a new, effectively a 'disable', type for video
device.
Reviewed-by: NJán Tomko <jtomko@redhat.com>
Signed-off-by: NErik Skultety <eskultet@redhat.com>

docs/formatdomain.html.in

@@ -6688,9 +6688,18 @@ qemu-kvm -net nic,model=? /dev/null
           The <code>model</code> element has a mandatory <code>type</code>
           attribute which takes the value "vga", "cirrus", "vmvga", "xen",
           "vbox", "qxl" (<span class="since">since 0.8.6</span>),
-          "virtio" (<span class="since">since 1.3.0</span>)
-          or "gop" (<span class="since">since 3.2.0</span>)
+          "virtio" (<span class="since">since 1.3.0</span>),
+          "gop" (<span class="since">since 3.2.0</span>), or
+          "none" (<span class="since">since 4.6.0</span>)
           depending on the hypervisor features available.
+          The purpose of the type <code>none</code> is to instruct libvirt not
+          to add a default video device in the guest (see the paragraph above).
+          This legacy behaviour can be inconvenient in cases where GPU mediated
+          devices are meant to be the only rendering device within a guest and
+          so specifying another <code>video</code> device along with type
+          <code>none</code>.
+          Refer to <a id="elementsHostDev">Host device assignment</a> to see
+          how to add a mediated device into a guest.
         </p>
         <p>
           You can provide the amount of video memory in kibibytes (blocks of

docs/schemas/domaincommon.rng

@@ -3454,6 +3454,7 @@
                 <value>vbox</value>
                 <value>virtio</value>
                 <value>gop</value>
+                <value>none</value>
               </choice>
             </attribute>
             <group>

src/conf/domain_conf.c

@@ -590,7 +590,8 @@ VIR_ENUM_IMPL(virDomainVideo, VIR_DOMAIN_VIDEO_TYPE_LAST,
               "qxl",
               "parallels",
               "virtio",
-              "gop")
+              "gop",
+              "none")
 
 VIR_ENUM_IMPL(virDomainVideoVGAConf, VIR_DOMAIN_VIDEO_VGACONF_LAST,
               "io",
@@ -5096,22 +5097,30 @@ virDomainDefPostParseVideo(virDomainDefPtr def,
     if (def->nvideos == 0)
         return 0;
 
-    virDomainDeviceDef device = {
-        .type = VIR_DOMAIN_DEVICE_VIDEO,
-        .data.video = def->videos[0],
-    };
+    if (def->videos[0]->type == VIR_DOMAIN_VIDEO_TYPE_NONE) {
+        /* we don't want to format any values we automatically fill in for
+         * videos into the XML, so clear them
+         */
+        virDomainVideoDefClear(def->videos[0]);
+        def->videos[0]->type = VIR_DOMAIN_VIDEO_TYPE_NONE;
+    } else {
+        virDomainDeviceDef device = {
+            .type = VIR_DOMAIN_DEVICE_VIDEO,
+            .data.video = def->videos[0],
+        };
 
-    /* Mark the first video as primary. If the user specified
-     * primary="yes", the parser already inserted the device at
-     * def->videos[0]
-     */
-    def->videos[0]->primary = true;
+        /* Mark the first video as primary. If the user specified
+         * primary="yes", the parser already inserted the device at
+         * def->videos[0]
+         */
+        def->videos[0]->primary = true;
 
-    /* videos[0] might have been added in AddImplicitDevices, after we've
-     * done the per-device post-parse */
-    if (virDomainDefPostParseDeviceIterator(def, &device,
-                                            NULL, opaque) < 0)
-        return -1;
+        /* videos[0] might have been added in AddImplicitDevices, after we've
+         * done the per-device post-parse */
+        if (virDomainDefPostParseDeviceIterator(def, &device,
+                                                NULL, opaque) < 0)
+            return -1;
+    }
 
     return 0;
 }
@@ -5660,13 +5669,30 @@ virDomainHostdevDefValidate(const virDomainHostdevDef *hostdev)
 
 
 static int
-virDomainVideoDefValidate(const virDomainVideoDef *video)
+virDomainVideoDefValidate(const virDomainVideoDef *video,
+                          const virDomainDef *def)
 {
+    size_t i;
+
     if (video->type == VIR_DOMAIN_VIDEO_TYPE_DEFAULT) {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("missing video model and cannot determine default"));
         return -1;
     }
+
+    /* it doesn't make sense to pair video device type 'none' with any other
+     * types, there can be only a single video device in such case
+     */
+    for (i = 0; i < def->nvideos; i++) {
+        if (def->videos[i]->type == VIR_DOMAIN_VIDEO_TYPE_NONE &&
+            def->nvideos > 1) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("a '%s' video type must be the only video device "
+                             "defined for the domain"));
+            return -1;
+        }
+    }
+
     return 0;
 }
 
@@ -5728,7 +5754,7 @@ virDomainDeviceDefValidateInternal(const virDomainDeviceDef *dev,
         return virDomainHostdevDefValidate(dev->data.hostdev);
 
     case VIR_DOMAIN_DEVICE_VIDEO:
-        return virDomainVideoDefValidate(dev->data.video);
+        return virDomainVideoDefValidate(dev->data.video, def);
 
     case VIR_DOMAIN_DEVICE_MEMORY:
         return virDomainMemoryDefValidate(dev->data.memory);
@@ -15038,6 +15064,7 @@ virDomainVideoDefaultRAM(const virDomainDef *def,
     case VIR_DOMAIN_VIDEO_TYPE_PARALLELS:
     case VIR_DOMAIN_VIDEO_TYPE_VIRTIO:
     case VIR_DOMAIN_VIDEO_TYPE_GOP:
+    case VIR_DOMAIN_VIDEO_TYPE_NONE:
     case VIR_DOMAIN_VIDEO_TYPE_LAST:
     default:
         return 0;

src/conf/domain_conf.h

@@ -1424,6 +1424,7 @@ typedef enum {
     VIR_DOMAIN_VIDEO_TYPE_PARALLELS, /* pseudo device for VNC in containers */
     VIR_DOMAIN_VIDEO_TYPE_VIRTIO,
     VIR_DOMAIN_VIDEO_TYPE_GOP,
+    VIR_DOMAIN_VIDEO_TYPE_NONE,
 
     VIR_DOMAIN_VIDEO_TYPE_LAST
 } virDomainVideoType;

src/qemu/qemu_command.c

@@ -105,7 +105,8 @@ VIR_ENUM_IMPL(qemuVideo, VIR_DOMAIN_VIDEO_TYPE_LAST,
               "qxl",
               "", /* don't support parallels */
               "", /* no need for virtio */
-              "" /* don't support gop */);
+              "" /* don't support gop */,
+              "" /* 'none' doesn't make sense here */);
 
 VIR_ENUM_DECL(qemuDeviceVideo)
 
@@ -119,7 +120,8 @@ VIR_ENUM_IMPL(qemuDeviceVideo, VIR_DOMAIN_VIDEO_TYPE_LAST,
               "qxl-vga",
               "", /* don't support parallels */
               "virtio-vga",
-              "" /* don't support gop */);
+              "" /* don't support gop */,
+              "" /* 'none' doesn't make sense here */);
 
 VIR_ENUM_DECL(qemuDeviceVideoSecondary)
 
@@ -133,7 +135,8 @@ VIR_ENUM_IMPL(qemuDeviceVideoSecondary, VIR_DOMAIN_VIDEO_TYPE_LAST,
               "qxl",
               "", /* don't support parallels */
               "virtio-gpu",
-              "" /* don't support gop */);
+              "" /* don't support gop */,
+              "" /* 'none' doesn't make sense here */);
 
 VIR_ENUM_DECL(qemuSoundCodec)
 
@@ -4451,6 +4454,9 @@ qemuBuildVideoCommandLine(virCommandPtr cmd,
         char *str = NULL;
         virDomainVideoDefPtr video = def->videos[i];
 
+        if (video->type == VIR_DOMAIN_VIDEO_TYPE_NONE)
+            continue;
+
         if (video->primary) {
             if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_VIDEO_PRIMARY)) {
 

src/qemu/qemu_domain.c

@@ -4528,6 +4528,8 @@ static int
 qemuDomainDeviceDefValidateVideo(const virDomainVideoDef *video)
 {
     switch ((virDomainVideoType) video->type) {
+    case VIR_DOMAIN_VIDEO_TYPE_NONE:
+        return 0;
     case VIR_DOMAIN_VIDEO_TYPE_XEN:
     case VIR_DOMAIN_VIDEO_TYPE_VBOX:
     case VIR_DOMAIN_VIDEO_TYPE_PARALLELS:

src/qemu/qemu_domain_address.c

@@ -799,6 +799,7 @@ qemuDomainDeviceCalculatePCIConnectFlags(virDomainDeviceDefPtr dev,
 
         case VIR_DOMAIN_VIDEO_TYPE_DEFAULT:
         case VIR_DOMAIN_VIDEO_TYPE_GOP:
+        case VIR_DOMAIN_VIDEO_TYPE_NONE:
         case VIR_DOMAIN_VIDEO_TYPE_LAST:
             return 0;
         }
@@ -1510,7 +1511,8 @@ qemuDomainValidateDevicePCISlotsPIIX3(virDomainDefPtr def,
             goto cleanup;
     }
 
-    if (def->nvideos > 0) {
+    if (def->nvideos > 0 &&
+        def->videos[0]->type != VIR_DOMAIN_VIDEO_TYPE_NONE) {
         /* Because the PIIX3 integrated IDE/USB controllers are
          * already at slot 1, when qemu looks for the first free slot
          * to place the VGA controller (which is always the first
@@ -1518,6 +1520,7 @@ qemuDomainValidateDevicePCISlotsPIIX3(virDomainDefPtr def,
          * at slot 2.
          */
         virDomainVideoDefPtr primaryVideo = def->videos[0];
+
         if (virDeviceInfoPCIAddressWanted(&primaryVideo->info)) {
             memset(&tmp_addr, 0, sizeof(tmp_addr));
             tmp_addr.slot = 2;
@@ -2083,6 +2086,8 @@ qemuDomainAssignDevicePCISlots(virDomainDefPtr def,
 
     /* Video devices */
     for (i = 0; i < def->nvideos; i++) {
+        if (def->videos[i]->type == VIR_DOMAIN_VIDEO_TYPE_NONE)
+            continue;
 
         if (!virDeviceInfoPCIAddressWanted(&def->videos[i]->info))
             continue;

tests/domaincapsschemadata/full.xml

@@ -74,6 +74,7 @@
         <value>parallels</value>
         <value>virtio</value>
         <value>gop</value>
+        <value>none</value>
       </enum>
     </video>
     <hostdev supported='yes'>

tests/qemuxml2argvdata/video-invalid-multiple-devices.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static' cpuset='1-4,8-20,525'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i686</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'/>
+    <controller type='ide' index='0'/>
+    <controller type='pci' index='0' model='pci-root'/>
+    <video>
+      <model type='qxl'/>
+    </video>
+    <video>
+      <model type='none'/>
+    </video>
+    <memballoon model='virtio'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/video-none-device.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-i686 \
+-name QEMUGuest1 \
+-S \
+-machine pc,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,\
+server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot c \
+-usb \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \
+-device ide-drive,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0 \
+-vnc 127.0.0.1:0 \
+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3

tests/qemuxml2argvdata/video-none-device.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</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>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i686</emulator>
+    <disk type='block' device='disk'>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <graphics type='vnc'/>
+    <video>
+      <model type='none'/>
+    </video>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </memballoon>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1999,7 +1999,9 @@ mymain(void)
             QEMU_CAPS_DEVICE_VIRTIO_VGA,
             QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
             QEMU_CAPS_VIRTIO_GPU_MAX_OUTPUTS);
-    DO_TEST_PARSE_ERROR("video-invalid", NONE);
+    DO_TEST("video-none-device",
+            QEMU_CAPS_VNC);
+    DO_TEST_PARSE_ERROR("video-invalid-multiple-devices", NONE);
 
     DO_TEST("virtio-rng-default",
             QEMU_CAPS_DEVICE_VIRTIO_RNG,

tests/qemuxml2xmloutdata/video-none-device.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</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>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i686</emulator>
+    <disk type='block' device='disk'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='hda' bus='ide'/>
+      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
+    </disk>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <graphics type='vnc' port='-1' autoport='yes'>
+      <listen type='address'/>
+    </graphics>
+    <video>
+      <model type='none'/>
+    </video>
+    <memballoon model='virtio'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </memballoon>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -1143,6 +1143,7 @@ mymain(void)
             QEMU_CAPS_VIRTIO_GPU_MAX_OUTPUTS,
             QEMU_CAPS_VNC,
             QEMU_CAPS_DEVICE_VIRTIO_GPU_CCW);
+    DO_TEST("video-none-device", NONE);
 
     DO_TEST("intel-iommu",
             QEMU_CAPS_DEVICE_INTEL_IOMMU);