[cc +qemu-devel, +peterx] On Thu, 22 Jun 2017 22:18:06 +0530 Nitin Saxena <nitin....@gmail.com> wrote:
> Hi, > > I have a PCI device connected as an endpoint to Intel host machine. > The requirement is to run dpdk like user space data path application > in VM using PCI PF passthrough (SRIOV disabled). This application > works fine on host kernel and uses VFIO to get MSIX interrupts from > PCI device. We are trying to run this existing application in VM using > PCI passthrough. This application has capability to use > VFIO_IOMMU_TYPE1 as wells as VFIO_NOIOMMU. > > On Intel host machine VT-d has been enabled and using virt-manager PCI > device PF is assigned to the VM. This makes virt-manager to implicitly > binds PCI device PF to vfio with vfio_iommu_type1. The VM LINUX kernel > was booted with intel_iommu=on as boot parameter. > > My question: Is it possible that vfio can coexist in host (by > virt-manager) as well as VM (by application)? If yes, does application > running inside VM needs to configure VFIO with iommu_type=IOMMU or > iommu_type=no-iommu. > > In VM I tried inserting vfio_iommu_type1.ko kernel module which failed > with "No such device error". Thats why I am confused whether my > requirement is legitimate or not. What could be the best solution? This is really more of a QEMU question. In order to use vfio_iommu_type1 in the guest, you need an iommu in the guest. The most recent release of QEMU supports this with an emulated VT-d device. Therefore if you create a VM with emulated VT-d and a device assigned through vfio-pci, you can expose it to userspace in the VM with physical iommu protection. Without an iommu in the VM, you'd be limited to no-iommu support for VM userspace, the physical iommu would only protect the device to the extent of VM memory, no to specific userspace mappings within the VM. Thanks, Alex
