On Mon, Oct 14, 2019 at 7:50 PM Peter Xu <pet...@redhat.com> wrote: > > On Mon, Oct 14, 2019 at 01:28:49PM -0700, Jintack Lim wrote: > > Hi, > > Hello, Jintack, > Hi Peter,
> > > > I'm trying to pass through a physical network device to a nested VM > > using virtual IOMMU. While I was able to do it successfully using KVM > > and Xen guest hypervisors running in a VM respectively, I couldn't do > > it with Hyper-V as I described below. I wonder if anyone have > > successfully used virtual IOMMU in other hypervisors other than KVM > > and Xen? (like Hyper-V or VMware) > > > > The issue I have with Hyper-V is that Hyper-V gives an error that the > > underlying hardware is not capable of doing passthrough. The exact > > error message is as follows. > > > > Windows Power-shell > (Get-VMHost).IovSupportReasons > > The chipset on the system does not do DMA remapping, without which > > SR-IOV cannot be supported. > > > > I'm pretty sure that Hyper-V recognizes virtual IOMMU, though; I have > > enabled iommu in windows boot loader[1], and I see differences when > > booing a Windows VM with and without virtual IOMMU. I also checked > > that virtual IOMMU traces are printed. > > What traces have you checked? More explicitly, have you seen DMAR > enabled and page table setup for that specific device to be > pass-throughed? Thanks for the pointers. I checked that DMAR is NOT enabled. The only registers that Windows guest accessed were Version Register, Capability Register, and Extended Capability Register. On the other hand, a Linux guest accessed other registers and enabled DMAR. Here's a link to the trace I got using QEMU 4.1.0. Do you see anything interesting there? http://paste.ubuntu.com/p/YcSyxG9Z3x/ > > > > > I have tried multiple KVM/QEMU versions including the latest ones > > (kernel v5.3, QEMU 4.1.0) as well as two different Windows servers > > (2016 and 2019), but I see the same result. [4] > > > > I'd love to hear if somebody is using virtual IOMMU in Hyper-V or > > VMware successfully, especially for passthrough. I also appreciate if > > somebody can point out any configuration errors I have. > > > > Here's the qemu command line I use, basically from the QEMU vt-d > > page[2] and Hyper-v on KVM from kvmforum [3]. > > > > ./qemu/x86_64-softmmu/qemu-system-x86_64 -device > > intel-iommu,intremap=on,caching-mode=on -smp 6 -m 24G -M > > Have you tried to use 4-level IOMMU page table (aw-bits=48 on latest > QEMU, or x-aw-bits=48 on some old ones)? IIRC we've encountered > issues when trying to pass the SVVP Windows test with this, in which > 4-level is required. I'm not sure whether whether that is required in > general usages of vIOMMU in Windows. I just tried the option you mentioned, but it didn't change anything. BTW, what version of Windows was it? > > > q35,accel=kvm,kernel-irqchip=split -cpu > > host,hv_relaxed,hv_spinlocks=0x1fff,hv_vapic,hv_time -drive > > if=none,file=/vm/guest0.img,id=vda,cache=none,format=raw -device > > virtio-blk-pci,drive=vda --nographic -qmp > > unix:/var/run/qmp,server,nowait -serial > > telnet:127.0.0.1:4444,server,nowait -netdev > > user,id=net0,hostfwd=tcp::2222-:22 -device > > virtio-net-pci,netdev=net0,mac=de:ad:be:ef:f2:12 -netdev > > tap,id=net1,vhost=on,helper=/srv/vm/qemu/qemu-bridge-helper -device > > virtio-net-pci,netdev=net1,disable-modern=off,disable-legacy=on,mac=de:ad:be:ef:f2:11 > > -device vfio-pci,host=0000:06:10.0,id=net2 -monitor stdio -usb -device > > usb-tablet -rtc base=localtime,clock=host -vnc 127.0.0.1:4 --cdrom > > win19.iso --drive file=virtio-win.iso,index=3,media=cdrom > > -- > Peter Xu >
