On Fri, Oct 09, 2020 at 04:00:17PM +0200, François Ozog wrote:
we bumped into a complication of iommu group membership management if we want to have devices in a single IOVA. I don’t think it is relevant here but may be worth giving a thought just in case.
Hmm, we might not be using the same terminology here (to me IOVA is "I/O virtual address"). Do you know which system had this problem? Linux puts two devices in the same IOMMU group when it's not possible to isolate them from each other with the IOMMU. For example when they are on a conventional PCI bus where DMA transactions can be snooped by other devices. Or with hardware bugs, for example when the PCIe hierachy doesn't properly implement ACS isolation, or the IOMMU receives all DMA with RequesterID 0...
For stratos IOMMU groups would be a problem when assigning a hardware devices to a backend VM. But for virtio devices it's not a problem, the emulated bus won't have those isolation issues.
Thanks, Jean