On Fri, Mar 28, 2025 at 10:11:13AM +0100, Joel Granados wrote: > Custom qemu device: pci-ats-testdev > ------------------------------------- > To support IOMMU testing under qemu, the pci-ats-testdev [10] > (different from pci-testdev [11]) was used to emulate DMA transactions. > It is a full fledged pci device capable of executing emulated DMA > accesses. It was originally intended to test Linux kernel interactions > with devices that had a working Address Translation Cache (ATC) but can > become a platform capable of testing anything PCI/IOMMU related if > needed. Yes please! Maybe "pcie-testdev" rather than "pci-ats-testdev"? There are other PCIe features that are poorly tested at the moment, for example PASID and PRI. The programming model of devices that actually implement those can get too complex so we need something simpler to precisely stress the IOMMU driver infrastructure. Driver unit-tests alone aren't good enough for exercising TLB invalidation (DMA after removing a mapping must crash), tricky cleanup paths (eg. killing a process bound to a device that's issuing page requests), runtime PM, MSIs etc. I'm guessing testing newer/future features like TDISP would also benefit from a simple device. Some time back I needed a device like that to reproduce some tricky races but never got round to implementing extra PCIe features. Although this one [1] is based on virtio any programming interface should work as long as it can instruct the device to send precise DMA transactions, ideally many in parallel. Thanks, Jean [1] https://jpbrucker.net/git/linux/log/?h=virtio-dmatest/latest https://jpbrucker.net/git/qemu/log/?h=virtio-dmatest/latest
