On a Thursday in 2024, Michal Privoznik wrote:
This is a follow up of my previous commits. If the number of vCPUs exceeds some arbitrary value (255) then QEMU requires IOMMU with EIM and interemap enabled. But in turn, intremap IOMMU
s/interemap/intremap/
requires split I/O APIC (per virDomainDefIOMMUValidate()). Since
after my previous commits (e.g. v10.10.0-rc1~183) IOMMU is added
automagically, the I/O APIC can be also enabled automagically.
Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
---
src/qemu/qemu_postparse.c | 7 +++++++
tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml | 3 ---
2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/src/qemu/qemu_postparse.c b/src/qemu/qemu_postparse.c
index 03b5ef825a..f48f172c37 100644
--- a/src/qemu/qemu_postparse.c
+++ b/src/qemu/qemu_postparse.c
@@ -1547,6 +1547,13 @@ qemuDomainDefEnableDefaultFeatures(virDomainDef *def,
* capabilities, we still want to enable this */
def->features[VIR_DOMAIN_FEATURE_GIC] = VIR_TRISTATE_SWITCH_ON;
}
+
+ /* IOMMU with intremap requires split I/O APIC */
The error message in hw/i386/x86-iommu.c suggests otherwise:
/* Both Intel and AMD IOMMU IR only support "kernel-irqchip={off|split}" */
if (x86_iommu_ir_supported(x86_iommu) && irq_all_kernel) {
error_setg(errp, "Interrupt Remapping cannot work with "
"kernel-irqchip=on, please use 'split|off'.");
return;
}
+ if (def->iommu &&
+ def->iommu->intremap == VIR_TRISTATE_SWITCH_ON &&
+ def->features[VIR_DOMAIN_FEATURE_IOAPIC] == VIR_DOMAIN_IOAPIC_NONE) {
+ def->features[VIR_DOMAIN_FEATURE_IOAPIC] = VIR_DOMAIN_IOAPIC_QEMU;
+ }
This should be only done if the IOMMU was auto-added, to not override it for user-specified IOMMU. (Sadly, this is one of those enums that does not distinguish between off and not specified) Jano
}
diff --git a/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
index fa3aaf0d44..5abc40e566 100644
--- a/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
+++ b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
@@ -8,9 +8,6 @@
<type arch='x86_64' machine='q35'>hvm</type>
<boot dev='hd'/>
</os>
- <features>
- <ioapic driver='qemu'/>
- </features>
<cpu mode='custom' match='exact' check='none'>
<model fallback='forbid'>qemu64</model>
</cpu>
--
2.45.2
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