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jaine avatar Server

Passing a raid controller to a KVM vm using PCI passthrough, CPU soft lockup

cn flag
jaine

I have a Debian 10 host server, and an Ubuntu 20.04 guest with KVM. The Ubuntu server is created with virt-install and works as intended after install. I'm trying to use PCI passthrough to pass a raid controller (Adaptec 81605Z) to the guest. With virsh edit my_vm I've added

<hostdev mode='subsystem' type='pci' managed='yes'>
  <driver name='vfio'/>
  <source>
    <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
  </source>
</hostdev>

to the configuration. Then I've used virsh nodedev-dettach pci_0000_01_00_0 to detach the raid controller from the host, after which lspci -nnv shows

01:00.0 RAID bus controller [0104]: Adaptec Series 8 12G SAS/PCIe 3 [9005:028d] (rev 01)
    Subsystem: Adaptec Series 8 12G SAS/PCIe 3 [9005:0557]
    Flags: fast devsel, IRQ 16
    Memory at a2100000 (64-bit, non-prefetchable) [size=1M]
    Memory at a2280000 (64-bit, non-prefetchable) [size=1K]
    I/O ports at 4000 [size=256]
    Expansion ROM at a2200000 [disabled] [size=512K]
    Capabilities: [80] Power Management version 3
    Capabilities: [90] MSI: Enable- Count=1/32 Maskable+ 64bit+
    Capabilities: [b0] MSI-X: Enable- Count=64 Masked-
    Capabilities: [c0] Express Endpoint, MSI 00
    Capabilities: [100] Advanced Error Reporting
    Capabilities: [300] #19
    Kernel driver in use: vfio-pci
    Kernel modules: aacraid

However, when I start my vm with virsh start my_vm --console, the console just gets stuck, nothing is printed, so something seems to be wrong as the vm doesn't boot. After a moment I start getting

kernel:[  747.764965] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [qemu-system-x86:1305]

errors and my host machine considerably slows down. I have disabled kvm from the vm as that might cause problems. My vm has 4GB of ram and 4 VCPUs allocated for it.

Is there something wrong with my configuration?

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Michael Hampton avatar
cz flag
Michael Hampton
Check `dmesg` on the host.
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jaine avatar
cn flag
jaine
I get the following messages concerning the vfio-pci: `[ 564.743353] vfio-pci 0000:01:00.0: vfio_ecap_init: hiding ecap 0x19@0x300`, after which I get a few of `[ 566.554256] vfio-pci 0000:01:00.0: not ready 1023ms after FLR; waiting` and then `[ 634.041210] vfio-pci 0000:01:00.0: not ready 65535ms after FLR; giving up`
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Zac67 avatar
ru flag
Zac67
Likely, the hardware driver doesn't support passthrough. You should consider mounting the RAID arrays on the host and just provide access to the guest.
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jaine avatar
cn flag
jaine
From other forums I've seen at least some people passing Adaptec controllers with PCI passthrough. For example [here](https://forums.servethehome.com/index.php?threads/epyc-rome-unable-to-pass-through-sata-ports-to-vm-flr-bug.28592/). How do I know if it's possible or not?
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