------- Original Message ------- On Tuesday, June 7th, 2022 at 3:04 AM, Andrew Cooper <[email protected]> wrote: > But IOMMU violations are not restartable. We can't just take an IOMMU > fault, and shuffle the guests memory, because the PCIe protocol has > timeouts. These aren't generally long enough to even send an interrupt > to request software help, let alone page one part out and another part in. > > For an IOMMU mapping to exists, it must point at real RAM, because any > DMA targetting it cannot be paused and delayed for later. >
Thanks for the information! Speaking about IOMMU. Can Xen emulate virtual IOMMU? Just thinking out loud. If Xen exposes a virtual IOMMU to a guest VM, wouldn't it be possible for the hypervisor to pin VM's pages that are mapped (dynamically) by the guest virtual IOMMU? But I guess it will eliminate the performance benefits of direct device assignment.
