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Diffstat (limited to 'releasenotes/notes/guest-iommu-device-4795c3a060aca424.yaml')
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diff --git a/releasenotes/notes/guest-iommu-device-4795c3a060aca424.yaml b/releasenotes/notes/guest-iommu-device-4795c3a060aca424.yaml new file mode 100644 index 0000000000..314c2c0ffe --- /dev/null +++ b/releasenotes/notes/guest-iommu-device-4795c3a060aca424.yaml @@ -0,0 +1,21 @@ +--- +features: + - | + The Libvirt driver can now add a virtual IOMMU device + to all created guests, when running on an x86 host and using the Q35 + machine type or on AArch64. + + To enable this, provide `hw:viommu_model` in flavor extra + spec or equivalent image metadata property `hw_viommu_model` and with the + guest CPU architecture and OS allows, we will enable viommu in Libvirt + driver. Support values intel|smmuv3|virtio|auto. Default to ``auto``. + Which ``auto`` will automatically select ``virtio`` if Libvirt supports it, + else ``intel`` on X86 (Q35) and ``smmuv3`` on AArch64. + vIOMMU config will raise invalid exception if the guest architecture is + neither X86 (Q35) or AArch64. + + Note that, enable vIOMMU might introduce significant performance overhead. + You can see performance comparision table from + `AMD vIOMMU session on KVM Forum 2021`_. + For above reason, vIOMMU should only be enable for workflow that require it. + .. _`AMD vIOMMU session on KVM Forum 2021`: https://static.sched.com/hosted_files/kvmforum2021/da/vIOMMU%20KVM%20Forum%202021%20-%20v4.pdf |