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qemu: require memfd memory for virtio 'blob' support 

The virtio-gpu 'blob' support was insufficiently validated. Qemu
requires a memfd memory backing in order to use udmabuf and enable blob
support. Example error:

    $ virsh start rhel9
    error: Failed to start domain 'rhel9'
    error: internal error: qemu unexpectedly closed the monitor: 2023-07-18T02:33:57.083178Z qemu-kvm: -device {"driver":"virtio-vga","id":"video0","max_outputs":1,"blob":true,"bus":"pcie.0","addr":"0x1"}: cannot enable blob resources without udmabuf

Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
This commit is contained in:
Jonathon Jongsma 2023-07-18 08:55:13 -05:00
parent ecbce92371
commit 988f8443fb
4 changed files with 21 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/qemu/qemu_validate.c
View File

@ -2598,6 +2598,7 @@ qemuValidateDomainDeviceDefHostdev(const virDomainHostdevDef *hostdev,
static int
qemuValidateDomainDeviceDefVideo(const virDomainVideoDef *video,
const virDomainDef *def,
virQEMUCaps *qemuCaps)
{
virDomainCapsDeviceVideo videoCaps = { 0 };
@ -2714,11 +2715,18 @@ qemuValidateDomainDeviceDefVideo(const virDomainVideoDef *video,
}
if (video->type == VIR_DOMAIN_VIDEO_TYPE_VIRTIO) {
if (video->blob != VIR_TRISTATE_SWITCH_ABSENT &&
!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_GPU_BLOB)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("this QEMU does not support 'blob' for virtio-gpu devices"));
return -1;
if (video->blob != VIR_TRISTATE_SWITCH_ABSENT) {
if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_GPU_BLOB)) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("this QEMU does not support 'blob' for virtio-gpu devices"));
return -1;
}
if (video->blob == VIR_TRISTATE_SWITCH_ON
&& def->mem.source != VIR_DOMAIN_MEMORY_SOURCE_MEMFD) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("'blob' support for virtio-gpu devices requires a memfd memory backend"));
return -1;
}
}
}
@ -5209,7 +5217,7 @@ qemuValidateDomainDeviceDef(const virDomainDeviceDef *dev,
qemuCaps);
case VIR_DOMAIN_DEVICE_VIDEO:
return qemuValidateDomainDeviceDefVideo(dev->data.video, qemuCaps);
return qemuValidateDomainDeviceDefVideo(dev->data.video, def, qemuCaps);
case VIR_DOMAIN_DEVICE_DISK:
return qemuValidateDomainDeviceDefDisk(dev->data.disk, def, qemuCaps);

2
tests/qemuxml2argvdata/video-virtio-blob-on.x86_64-latest.args
View File

@ -14,7 +14,7 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
-accel tcg \
-cpu qemu64 \
-m size=1048576k \
-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":1073741824}' \
-object '{"qom-type":"memory-backend-memfd","id":"pc.ram","x-use-canonical-path-for-ramblock-id":false,"size":1073741824}' \
-overcommit mem-lock=off \
-smp 1,sockets=1,cores=1,threads=1 \
-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \

3
tests/qemuxml2argvdata/video-virtio-blob-on.xml
View File

@ -3,6 +3,9 @@
<uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<memoryBacking>
<source type='memfd'/>
</memoryBacking>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='x86_64' machine='pc'>hvm</type>

3
tests/qemuxml2xmloutdata/video-virtio-blob-on.x86_64-latest.xml
View File

@ -3,6 +3,9 @@
<uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
<memory unit='KiB'>1048576</memory>
<currentMemory unit='KiB'>1048576</currentMemory>
<memoryBacking>
<source type='memfd'/>
</memoryBacking>
<vcpu placement='static'>1</vcpu>
<os>
<type arch='x86_64' machine='pc'>hvm</type>