[brendank310]

Relatively common nowadays. It used to be delineated as a feature in Intel chips as part of their vPro line, but I think it’s baked in. Generally an IOMMU is needed for performant PCI passthrough to VMs, and Windows uses it for DeviceGuard which tries to prevent DMA attacks.

[wtallis]

Mainstream consumer x86 processors have had IOMMU capability for over a decade, but for the first few years it was commonly disabled on certain parts for product segmentation (eg. i5-3570K had overclocking but no IOMMU, i5-3570 had IOMMU but limited overclocking). That practice died off approximately when Thunderbolt started to catch on, because not having an IOMMU when using Thunderbolt would have been very bad.

[p_l]

Seems to me that Zen 4 has no issues at all, but bridges/switches require additional interfaces to further fan-out access controls.