conf: Add <disk model='virtio-{non-}transitional'/>

<disk> devices lack the model= attribute which is used by
most other device types. bus= mostly acts as one, but it
serves other purposes too like determing what target=
prefix to use, and for matching against controller type=
values.

Extending bus= to handle additional virtio transitional
devices will complicate apps lives, and it isn't a clean
mapping anyways. So let's bite the bullet and add a new
<disk model=X/> attribute, and wire up common handling
for virtio and virtio-{non-}transitional
Reviewed-by: NAndrea Bolognani <abologna@redhat.com>
Signed-off-by: NCole Robinson <crobinso@redhat.com>

docs/formatdomain.html.in

@@ -2932,6 +2932,17 @@
             <span class="since">Since 0.1.4</span>
             </p>
             </dd>
+          <dt><code>model</code></dt>
+            <dd>
+            Indicates the emulated device model of the disk. Typically
+            this is indicated solely by the <code>bus</code> property but
+            for <code>bus</code> "virtio" the model can be specified further
+            with "virtio-transitional", "virtio-non-transitional", or
+            "virtio". See
+            <a href="#elementsVirtioTransitional">Virtio transitional devices</a>
+            for more details.
+            <span class="since">Since 5.2.0</span>
+            </dd>
           <dt><code>rawio</code></dt>
             <dd>
             Indicates whether the disk needs rawio capability. Valid
@@ -4084,6 +4095,45 @@
       <span class="since">Since 3.5.0</span>
     </p>
 
+    <h4><a id="elementsVirtioTransitional">Virtio transitional devices</a></h4>
+
+    <p>
+      <span class="since">Since 5.2.0</span>, some of QEMU's virtio devices,
+      when used with PCI/PCIe machine types, accept the following
+      <code>model</code> values:
+    </p>
+
+    <dl>
+      <dt><code>virtio-transitional</code></dt>
+      <dd>This device can work both with virtio 0.9 and virtio 1.0 guest
+      drivers, so it's the best choice when compatibility with older
+      guest operating systems is desired. libvirt will plug the device
+      into a conventional PCI slot.
+      </dd>
+      <dt><code>virtio-non-transitional</code></dt>
+      <dd>This device can only work with virtio 1.0 guest drivers, and it's
+      the recommended option unless compatibility with older guest
+      operating systems is necessary. libvirt will plug the device into
+      either a PCI Express slot or a conventional PCI slot based on the
+      machine type, resulting in a more optimized PCI topology.
+      </dd>
+      <dt><code>virtio</code></dt>
+      <dd>This device will work like a <code>virtio-non-transitional</code>
+      device when plugged into a PCI Express slot, and like a
+      <code>virtio-transitional</code> device otherwise; libvirt will
+      pick one or the other based on the machine type. This is the best
+      choice when compatibility with libvirt versions older than 5.1.0
+      is necessary, but it's otherwise not recommended to use it.
+      </dd>
+    </dl>
+
+    <p>
+      For more details see the
+      <a href="https://lists.gnu.org/archive/html/qemu-devel/2018-12/msg00923.html">qemu patch posting</a> and the
+      <a href="http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.html">virtio-1.0 spec</a>.
+    </p>
+
+
     <h4><a id="elementsControllers">Controllers</a></h4>
 
     <p>

docs/schemas/domaincommon.rng

@@ -1509,6 +1509,15 @@
           </interleave>
         </group>
       </choice>
+      <optional>
+        <attribute name="model">
+          <choice>
+            <value>virtio</value>
+            <value>virtio-transitional</value>
+            <value>virtio-non-transitional</value>
+          </choice>
+        </attribute>
+      </optional>
       <optional>
         <ref name="snapshot"/>
       </optional>

src/conf/domain_conf.c

@@ -991,6 +991,13 @@ VIR_ENUM_IMPL(virDomainDiskDetectZeroes, VIR_DOMAIN_DISK_DETECT_ZEROES_LAST,
               "unmap",
 );
 
+VIR_ENUM_IMPL(virDomainDiskModel, VIR_DOMAIN_DISK_MODEL_LAST,
+              "default",
+              "virtio",
+              "virtio-transitional",
+              "virtio-non-transitional",
+);
+
 VIR_ENUM_IMPL(virDomainDiskMirrorState, VIR_DOMAIN_DISK_MIRROR_STATE_LAST,
               "none",
               "yes",
@@ -5688,6 +5695,17 @@ virDomainDiskDefValidate(const virDomainDiskDef *disk)
         return -1;
     }
 
+    if (disk->bus != VIR_DOMAIN_DISK_BUS_VIRTIO &&
+        (disk->model == VIR_DOMAIN_DISK_MODEL_VIRTIO ||
+         disk->model == VIR_DOMAIN_DISK_MODEL_VIRTIO_TRANSITIONAL ||
+         disk->model == VIR_DOMAIN_DISK_MODEL_VIRTIO_NON_TRANSITIONAL)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("disk model '%s' not supported for bus '%s'"),
+                       virDomainDiskModelTypeToString(disk->model),
+                       virDomainDiskBusTypeToString(disk->bus));
+        return -1;
+    }
+
     return 0;
 }
 
@@ -9643,6 +9661,14 @@ virDomainDiskDefParseXML(virDomainXMLOptionPtr xmlopt,
     }
     VIR_FREE(tmp);
 
+    if ((tmp = virXMLPropString(node, "model")) &&
+        (def->model = virDomainDiskModelTypeFromString(tmp)) < 0) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("unknown disk model '%s'"), tmp);
+        goto error;
+    }
+    VIR_FREE(tmp);
+
     snapshot = virXMLPropString(node, "snapshot");
 
     rawio = virXMLPropString(node, "rawio");
@@ -21480,6 +21506,14 @@ virDomainDiskDefCheckABIStability(virDomainDiskDefPtr src,
         return false;
     }
 
+    if (src->model != dst->model) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target disk model %s does not match source %s"),
+                       virDomainDiskModelTypeToString(dst->model),
+                       virDomainDiskModelTypeToString(src->model));
+        return false;
+    }
+
     if (src->virtio && dst->virtio &&
         !virDomainVirtioOptionsCheckABIStability(src->virtio, dst->virtio))
         return false;
@@ -24034,6 +24068,12 @@ virDomainDiskDefFormat(virBufferPtr buf,
     virBufferAsprintf(buf,
                       "<disk type='%s' device='%s'",
                       type, device);
+
+    if (def->model) {
+        virBufferAsprintf(buf, " model='%s'",
+                          virDomainDiskModelTypeToString(def->model));
+    }
+
     if (def->rawio) {
         virBufferAsprintf(buf, " rawio='%s'",
                           virTristateBoolTypeToString(def->rawio));

src/conf/domain_conf.h

@@ -567,6 +567,15 @@ typedef enum {
     VIR_DOMAIN_DISK_DETECT_ZEROES_LAST
 } virDomainDiskDetectZeroes;
 
+typedef enum {
+    VIR_DOMAIN_DISK_MODEL_DEFAULT = 0,
+    VIR_DOMAIN_DISK_MODEL_VIRTIO,
+    VIR_DOMAIN_DISK_MODEL_VIRTIO_TRANSITIONAL,
+    VIR_DOMAIN_DISK_MODEL_VIRTIO_NON_TRANSITIONAL,
+
+    VIR_DOMAIN_DISK_MODEL_LAST
+} virDomainDiskModel;
+
 typedef struct _virDomainBlockIoTuneInfo virDomainBlockIoTuneInfo;
 struct _virDomainBlockIoTuneInfo {
     unsigned long long total_bytes_sec;
@@ -674,6 +683,7 @@ struct _virDomainDiskDef {
     int detect_zeroes; /* enum virDomainDiskDetectZeroes */
     char *domain_name; /* backend domain name */
     unsigned int queues;
+    int model; /* enum virDomainDiskModel */
     virDomainVirtioOptionsPtr virtio;
 };
 
@@ -3439,6 +3449,7 @@ VIR_ENUM_DECL(virDomainDeviceSGIO);
 VIR_ENUM_DECL(virDomainDiskTray);
 VIR_ENUM_DECL(virDomainDiskDiscard);
 VIR_ENUM_DECL(virDomainDiskDetectZeroes);
+VIR_ENUM_DECL(virDomainDiskModel);
 VIR_ENUM_DECL(virDomainDiskMirrorState);
 VIR_ENUM_DECL(virDomainController);
 VIR_ENUM_DECL(virDomainControllerModelPCI);

src/libvirt_private.syms

@@ -343,6 +343,8 @@ virDomainDiskIoTypeFromString;
 virDomainDiskIoTypeToString;
 virDomainDiskMirrorStateTypeFromString;
 virDomainDiskMirrorStateTypeToString;
+virDomainDiskModelTypeFromString;
+virDomainDiskModelTypeToString;
 virDomainDiskPathByName;
 virDomainDiskRemove;
 virDomainDiskRemoveByName;

tests/qemuxml2argvdata/virtio-non-transitional.x86_64-3.1.0.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
+-machine pc-q35-3.1,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot strict=on \
+-device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,\
+addr=0x1 \
+-device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x0,drive=drive-virtio-disk0,\
+id=virtio-disk0,bootindex=1 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxml2argvdata/virtio-non-transitional.x86_64-latest.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
+-machine q35,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot strict=on \
+-device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,\
+addr=0x1 \
+-device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x0,drive=drive-virtio-disk0,\
+id=virtio-disk0,bootindex=1 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxml2argvdata/virtio-non-transitional.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+  </os>
+  <devices>
+    <disk type='block' device='disk' model='virtio-non-transitional'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='vda' bus='virtio'/>
+    </disk>
+    <controller type='usb' model='none'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/virtio-transitional.x86_64-3.1.0.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
+-machine pc-q35-3.1,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot strict=on \
+-device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,\
+addr=0x1 \
+-device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x0,drive=drive-virtio-disk0,\
+id=virtio-disk0,bootindex=1 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxml2argvdata/virtio-transitional.x86_64-latest.args

+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object secret,id=masterKey0,format=raw,\
+file=/tmp/lib/domain--1-QEMUGuest1/master-key.aes \
+-machine q35,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server,nowait \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-boot strict=on \
+-device pcie-root-port,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,\
+addr=0x1 \
+-device pcie-root-port,port=0x9,chassis=2,id=pci.2,bus=pcie.0,addr=0x1.0x1 \
+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,scsi=off,bus=pci.1,addr=0x0,drive=drive-virtio-disk0,\
+id=virtio-disk0,bootindex=1 \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,\
+resourcecontrol=deny \
+-msg timestamp=on

tests/qemuxml2argvdata/virtio-transitional.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+  </os>
+  <devices>
+    <disk type='block' device='disk' model='virtio-transitional'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='vda' bus='virtio'/>
+    </disk>
+    <controller type='usb' model='none'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -2996,6 +2996,12 @@ mymain(void)
     DO_TEST("riscv64-virt-pci",
             QEMU_CAPS_OBJECT_GPEX);
 
+    /* Older version checks disable-legacy usage */
+    DO_TEST_CAPS_VER("virtio-transitional", "3.1.0");
+    DO_TEST_CAPS_VER("virtio-non-transitional", "3.1.0");
+    DO_TEST_CAPS_LATEST("virtio-transitional");
+    DO_TEST_CAPS_LATEST("virtio-non-transitional");
+
     /* Simple headless guests for various architectures */
     DO_TEST_CAPS_ARCH_LATEST("aarch64-virt-headless", "aarch64");
     DO_TEST_CAPS_ARCH_LATEST("ppc64-pseries-headless", "ppc64");

tests/qemuxml2xmloutdata/virtio-non-transitional.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='x86_64' machine='q35'>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-x86_64</emulator>
+    <disk type='block' device='disk' model='virtio-non-transitional'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='vda' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
+    </disk>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='1' port='0x8'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/>
+    </controller>
+    <controller type='pci' index='2' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='2' port='0x9'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmloutdata/virtio-transitional.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='x86_64' machine='q35'>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-x86_64</emulator>
+    <disk type='block' device='disk' model='virtio-transitional'>
+      <driver name='qemu' type='raw'/>
+      <source dev='/dev/HostVG/QEMUGuest1'/>
+      <target dev='vda' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
+    </disk>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='pci' index='1' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='1' port='0x8'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/>
+    </controller>
+    <controller type='pci' index='2' model='pcie-root-port'>
+      <model name='pcie-root-port'/>
+      <target chassis='2' port='0x9'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2xmltest.c

@@ -1254,6 +1254,17 @@ mymain(void)
     DO_TEST("riscv64-virt-pci",
             QEMU_CAPS_OBJECT_GPEX);
 
+    DO_TEST("virtio-transitional",
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
+            QEMU_CAPS_DEVICE_PCIE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_PCIE_ROOT_PORT,
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY);
+    DO_TEST("virtio-non-transitional",
+            QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
+            QEMU_CAPS_DEVICE_PCIE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_PCIE_ROOT_PORT,
+            QEMU_CAPS_VIRTIO_PCI_DISABLE_LEGACY);
+
     if (getenv("LIBVIRT_SKIP_CLEANUP") == NULL)
         virFileDeleteTree(fakerootdir);