On Fri, Apr 12, 2024 at 08:43:48PM -0700, Nicolin Chen wrote: > The user-space support is to provide uAPIs (via IOMMUFD) for hypervisors > in user space to passthrough VCMDQs to VMs, allowing these VMs to access > the VCMDQs directly without trappings, i.e. no VM Exits. This gives huge > performance improvements: 70% to 90% reductions of TLB invalidation time > were measured by various DMA unmap tests running in a guest OS, compared > to a nested SMMU CMDQ (with trappings). So everyone is on the same page, this is the primary point of this series. The huge speed up of in-VM performance is necessary for the workloads this chip is expected to be running. This series is unique from all the rest because it runs inside a VM, often in the from of a distro release. It doesn't need the other series or it's own part 2 as it entirely stands alone on bare metal hardware or on top of commercial VM cloud instances runing who-knows-what in their hypervisors. The other parts are substantially about enabling qemu and the open ecosystem to have fully functional vSMMU3 virtualization. Jason
