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qemu_domain: Automagically add IOMMU if needed

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If a Q35 domain has huge number of vCPUS (over 255, currently), then
it needs IOMMU with Extended Interrupt Mode enabled (see check in
qemuValidateDomainVCpuTopology()).

Well, we already add some devices and to other tricks when
parsing new domain XML. Might as well add IOMMU device if above
condition is met.

Resolves: https://issues.redhat.com/browse/RHEL-65844
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
This commit is contained in:
Michal Privoznik 2024-11-06 12:57:21 +01:00
parent b15047ff26
commit 844d1036eb
2 changed files with 20 additions and 1 deletions
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20
src/qemu/qemu_domain.c
View File

@ -4262,6 +4262,7 @@ qemuDomainDefAddDefaultDevices(virQEMUDriver *driver,
bool addDefaultUSBMouse = false;
bool addPanicDevice = false;
bool addITCOWatchdog = false;
bool addIOMMU = false;
/* add implicit input devices */
if (qemuDomainDefAddImplicitInputDevice(def, qemuCaps) < 0)
@ -4284,6 +4285,10 @@ qemuDomainDefAddDefaultDevices(virQEMUDriver *driver,
addImplicitSATA = true;
addITCOWatchdog = true;
if (virDomainDefGetVcpusMax(def) > QEMU_MAX_VCPUS_WITHOUT_EIM) {
addIOMMU = true;
}
/* Prefer adding a USB3 controller if supported, fall back
* to USB2 if there is no USB3 available, and if that's
* unavailable don't add anything.
@ -4530,6 +4535,21 @@ qemuDomainDefAddDefaultDevices(virQEMUDriver *driver,
}
}
if (addIOMMU && !def->iommu &&
virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_INTEL_IOMMU) &&
virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_INTREMAP) &&
virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_EIM)) {
g_autoptr(virDomainIOMMUDef) iommu = NULL;
iommu = virDomainIOMMUDefNew();
iommu->model = VIR_DOMAIN_IOMMU_MODEL_INTEL;
/* eim requires intremap. */
iommu->intremap = VIR_TRISTATE_SWITCH_ON;
iommu->eim = VIR_TRISTATE_SWITCH_ON;
def->iommu = g_steal_pointer(&iommu);
}
if (qemuDomainDefAddDefaultAudioBackend(driver, def) < 0)
return -1;

1
tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
View File

@ -30,6 +30,5 @@
<audio id='1' type='none'/>
<watchdog model='itco' action='reset'/>
<memballoon model='none'/>
<iommu model='intel'/>
</devices>
</domain>