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qemu: map "virtio" video model to "virt" machtype correctly (arm/aarch64)

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Most of QEMU's PCI display device models, such as:

  libvirt video/model/@type  QEMU -device
  -------------------------  ------------
  cirrus                     cirrus-vga
  vga                        VGA
  qxl                        qxl-vga
  virtio                     virtio-vga

come with a linear framebuffer (sometimes called "VGA compatibility
framebuffer"). This linear framebuffer lives in one of the PCI device's
MMIO BARs, and allows guest code (primarily: firmware drivers, and
non-accelerated OS drivers) to display graphics with direct memory access.

Due to architectural reasons on aarch64/KVM hosts, this kind of
framebuffer doesn't / can't work in

  qemu-system-(arm|aarch64) -M virt

machines. Cache coherency issues guarantee a corrupted / unusable display.
The problem has been researched by several people, including kvm-arm
maintainers, and it's been decided that the best way (practically the only
way) to have boot time graphics for such guests is to consolidate on
QEMU's "virtio-gpu-pci" device.

>From <https://bugzilla.redhat.com/show_bug.cgi?id=1195176>, libvirt
supports

  <devices>
    <video>
      <model type='virtio'/>
    </video>
  </devices>

but libvirt unconditionally maps @type='virtio' to QEMU's "virtio-vga"
device model. (See the qemuBuildDeviceVideoStr() function and the
"qemuDeviceVideo" enum impl.)

According to the above, this is not right for the "virt" machine type; the
qemu-system-(arm|aarch64) binaries don't even recognize the "virtio-vga"
device model (justifiedly). Whereas "virtio-gpu-pci", which is a pure
virtio device without a compatibility framebuffer, is available, and works
fine.

(The ArmVirtQemu ("AAVMF") platform of edk2 -- that is, the UEFI firmware
for "virt" -- supports "virtio-gpu-pci", as of upstream commit
3ef3209d3028. See
<https://tianocore.acgmultimedia.com/show_bug.cgi?id=66>.)

Override the default mapping of "virtio", from "virtio-vga" to
"virtio-gpu-pci", if qemuDomainMachineIsVirt() evaluates to true.

Cc: Andrea Bolognani <abologna@redhat.com>
Cc: Drew Jones <drjones@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Martin Kletzander <mkletzan@redhat.com>
Suggested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1372901
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Acked-by: Martin Kletzander <mkletzan@redhat.com>
This commit is contained in:
Laszlo Ersek 2016-09-16 09:30:23 +02:00 committed by Pavel Hrdina
parent b51e26f755
commit 706b5b6277
6 changed files with 121 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
src/qemu/qemu_command.c
View File

@ -4325,6 +4325,10 @@ qemuBuildDeviceVideoStr(const virDomainDef *def,
virDomainVideoTypeToString(video->type));
goto error;
}
if (video->type == VIR_DOMAIN_VIDEO_TYPE_VIRTIO &&
qemuDomainMachineIsVirt(def)) {
model = "virtio-gpu-pci";
}
} else {
if (video->type != VIR_DOMAIN_VIDEO_TYPE_QXL) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

26
tests/qemuxml2argvdata/qemuxml2argv-aarch64-video-virtio-gpu-pci.args Normal file
View File

@ -0,0 +1,26 @@
LC_ALL=C \
PATH=/bin \
HOME=/home/test \
USER=test \
LOGNAME=test \
QEMU_AUDIO_DRV=none \
/opt/qemu-installed/bin/qemu-system-aarch64 \
-name aarch64-vgpu \
-S \
-M virt \
-cpu cortex-a57 \
-m 1024 \
-smp 1,sockets=1,cores=1,threads=1 \
-uuid f3197c89-6457-44fe-b26d-897090ba6541 \
-nographic \
-nodefconfig \
-nodefaults \
-monitor unix:/tmp/lib/domain--1-aarch64-vgpu/monitor.sock,server,nowait \
-device ioh3420,port=0x8,chassis=1,id=pci.1,bus=pcie.0,multifunction=on,\
addr=0x1 \
-device ioh3420,port=0x9,chassis=2,id=pci.2,bus=pcie.0,multifunction=on,\
addr=0x1.0x1 \
-device virtio-net-pci,vlan=0,id=net0,mac=52:54:00:73:34:53,bus=pci.1,addr=0x0,\
bootindex=1 \
-net user,vlan=0,name=hostnet0 \
-device virtio-gpu-pci,id=video0,bus=pci.2,addr=0x0

36
tests/qemuxml2argvdata/qemuxml2argv-aarch64-video-virtio-gpu-pci.xml Normal file
View File

@ -0,0 +1,36 @@
<domain type='qemu'>
<name>aarch64-vgpu</name>
<uuid>f3197c89-6457-44fe-b26d-897090ba6541</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='aarch64' machine='virt'>hvm</type>
</os>
<features>
<acpi/>
</features>
<cpu mode='custom' match='exact'>
<model fallback='allow'>cortex-a57</model>
</cpu>
<devices>
<emulator>/opt/qemu-installed/bin/qemu-system-aarch64</emulator>
<controller type='pci' index='0' model='pcie-root'/>
<controller type='pci' index='1' model='pcie-root-port'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0' multifunction='on'/>
</controller>
<controller type='pci' index='2' model='pcie-root-port'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1' multifunction='on'/>
</controller>
<interface type='user'>
<mac address='52:54:00:73:34:53'/>
<model type='virtio'/>
<boot order='1'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>
<video>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
</video>
</devices>
</domain>

5
tests/qemuxml2argvtest.c
View File

@ -1872,6 +1872,11 @@ mymain(void)
QEMU_CAPS_DEVICE_VIRTIO_RNG, QEMU_CAPS_OBJECT_RNG_RANDOM,
QEMU_CAPS_OBJECT_GPEX, QEMU_CAPS_DEVICE_PCI_BRIDGE,
QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE, QEMU_CAPS_VIRTIO_SCSI);
DO_TEST("aarch64-video-virtio-gpu-pci",
QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_OBJECT_GPEX,
QEMU_CAPS_DEVICE_PCI_BRIDGE, QEMU_CAPS_DEVICE_IOH3420,
QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
QEMU_CAPS_DEVICE_VIRTIO_GPU, QEMU_CAPS_BOOTINDEX);
DO_TEST("aarch64-aavmf-virtio-mmio",
QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_DTB,
QEMU_CAPS_DEVICE_VIRTIO_MMIO,

45
tests/qemuxml2xmloutdata/qemuxml2xmlout-aarch64-video-virtio-gpu-pci.xml Normal file
View File

@ -0,0 +1,45 @@
<domain type='qemu'>
<name>aarch64-vgpu</name>
<uuid>f3197c89-6457-44fe-b26d-897090ba6541</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='aarch64' machine='virt'>hvm</type>
</os>
<features>
<acpi/>
<gic version='2'/>
</features>
<cpu mode='custom' match='exact'>
<model fallback='allow'>cortex-a57</model>
</cpu>
<clock offset='utc'/>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<devices>
<emulator>/opt/qemu-installed/bin/qemu-system-aarch64</emulator>
<controller type='pci' index='0' model='pcie-root'/>
<controller type='pci' index='1' model='pcie-root-port'>
<model name='ioh3420'/>
<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='ioh3420'/>
<target chassis='2' port='0x9'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1' multifunction='on'/>
</controller>
<interface type='user'>
<mac address='52:54:00:73:34:53'/>
<model type='virtio'/>
<boot order='1'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>
<video>
<model type='virtio' heads='1' primary='yes'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
</video>
</devices>
</domain>

5
tests/qemuxml2xmltest.c
View File

@ -831,6 +831,11 @@ mymain(void)
QEMU_CAPS_DEVICE_VIRTIO_RNG, QEMU_CAPS_OBJECT_RNG_RANDOM,
QEMU_CAPS_OBJECT_GPEX, QEMU_CAPS_DEVICE_PCI_BRIDGE,
QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE, QEMU_CAPS_VIRTIO_SCSI);
DO_TEST("aarch64-video-virtio-gpu-pci",
QEMU_CAPS_NODEFCONFIG, QEMU_CAPS_OBJECT_GPEX,
QEMU_CAPS_DEVICE_PCI_BRIDGE, QEMU_CAPS_DEVICE_IOH3420,
QEMU_CAPS_PCI_MULTIFUNCTION, QEMU_CAPS_DEVICE_VIDEO_PRIMARY,
QEMU_CAPS_DEVICE_VIRTIO_GPU, QEMU_CAPS_BOOTINDEX);
DO_TEST_FULL("aarch64-gic-none", WHEN_BOTH, GIC_NONE, NONE);
DO_TEST_FULL("aarch64-gic-none-v2", WHEN_BOTH, GIC_V2, NONE);