On Tue, 7 Feb 2017 11:46:57 -0500 Jintack Lim <jint...@cs.columbia.edu> wrote:
> Adding CC and some more information. $ ./scripts/get_maintainer.pl -f ./hw/i386/intel_iommu.c get_maintainer.pl: No maintainers found, printing recent contributors. get_maintainer.pl: Do not blindly cc: them on patches! Use common sense. "Michael S. Tsirkin" <m...@redhat.com> (commit_signer:54/35=100%) Peter Xu <pet...@redhat.com> (commit_signer:28/35=80%) Paolo Bonzini <pbonz...@redhat.com> (commit_signer:6/35=17%) Jason Wang <jasow...@redhat.com> (commit_signer:5/35=14%) "Radim Krčmář" <rkrc...@redhat.com> (commit_signer:5/35=14%) qemu-de...@nongnu.org (open list:All patches CC here) > On Tue, Feb 7, 2017 at 5:07 AM, Jintack Lim <jint...@cs.columbia.edu> wrote: > > Hi, > > > > I'm getting DMAR errors during VM booting when I enable the iommu > > emulation for the VM. I was not able to complete booting since the VM > > gets really slow and just keep printing the error message (sym0: > > unexpected disconnect) at a speed of one character per second. > > > > I have enabled the iommu emulation, but didn't assign any device to the VM. > > > > This is the kernel log from the VM > > I'm using 4.6.0-rc5+ kernel for the host and the VM. > > Here's the full kernel log from the VM. > https://paste.ubuntu.com/23948597/ > > > > > [ 6.087794] sym0: SCSI BUS has been reset. > > [ 6.087960] DMAR: DRHD: handling fault status reg 2 > > [ 6.088001] DMAR: DMAR:[DMA Read] Request device [04:03.0] fault > > addr fe281000 > > [ 6.088001] DMAR:[fault reason 06] PTE Read access is not set > > [ 6.090513] scsi host1: sym-2.2.3 > > [ 6.090567] sym0: unexpected disconnect > > [ 8.814929] sym0: unexpected disconnect > > [ 11.670251] sym0: unexpected disconnect > > > > I enabled iommu in the host (intel_iommu=on). I also enabled iommu in > > the guest AND gave this option to the qemu (-device intel-iommu). I'm > > using qemu 2.8.0 and libvirt 3.0.0. > > I used <qemu:commandline> in libvirt xml to enable iommu emulation. > > Here's the full libvirt xml. > > http://paste.ubuntu.com/23946803/ > > > > I did lspci -vvv and 04:03:0 is scsi device. Unfortunately, I lost > > that information, and can't boot the VM now. I'll add this information > > later if necessary. > > This is information about 04:03:0 > I got this from the another identical VM but not with the iommu emulation. > > root@guest0:~# lspci -vvs 04:03.0 > 04:03.0 SCSI storage controller: LSI Logic / Symbios Logic 53c895a > Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- > Stepping- SERR+ FastB2B- DisINTx- > Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- > <TAbort- <MAbort- >SERR- <PERR- INTx- > Latency: 255, Cache Line Size: 64 bytes > Interrupt: pin A routed to IRQ 23 > Region 0: I/O ports at c000 [size=256] > Region 1: Memory at fe284000 (32-bit, non-prefetchable) [size=1K] > Region 2: Memory at fe280000 (32-bit, non-prefetchable) [size=8K] > Kernel driver in use: sym53c8xx > > > > > Any thoughts why this happens and how to fix? Try a different disk controller in the VM? Running virtual VT-d can't automatically fix guest drivers that don't handle devices behind an IOMMU correctly. I don't know if that's the case, but I imagine 53c895a has probably never been tested w/ VT-d emulation. Note that when you do get to the point off assigning a device to the VM, you're going to need to build your own QEMU with patches from the mailing list, or maybe wait a few days and they might make it to the git tree. Thanks, Alex