[Qemu-devel] [Bug 799036] Re: NIC assignment order in command line make some NIC can't work

[Alex Williamson]

It looks like the critical difference in the working vs non-working case
is the host interrupts on the 82576.  When working, both the host and
guest view of the device is using MSI-X interrupts.  When not working,
the host is using MSI but the guest still thinks it's using MSI-X.
Those are not compatible.  I'm curious if this is already fixed by qemu-
kvm.git commit 096392ef which intends to prevent an update of the
chipset irq routing registers from causing the legacy interrupt to be
re-registered (which can legally use MSI) and it's stomping on the MSI-X
setup.  Please retest with latest bits (note that I just sent a couple
patches to the mailing list that unbreak MSI-X support which you'll need
to make this work).

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https://bugs.launchpad.net/bugs/799036

Title:
  NIC assignment order in command line make some NIC can't work

Status in QEMU:
  New

Bug description:
  Environment:
  ------------
  Host OS (ia32/ia32e/IA64):All
  Guest OS (ia32/ia32e/IA64):ia32e
  Guest OS Type (Linux/Windows):Linux 
  kvm.git Commit:681fb677ace0754589792c92b8dbee9884d07158
  qemu-kvm Commit:05f1737582ab6c075476bde931c5eafbc62a9349
  Host Kernel Version:3.0.0-rc2+
  Hardware: Westmere-EP platform

  Bug detailed description:
  --------------------------
  When using qemu-system-x86_64 to create a linux guest with a 82586 NIC and a 
82572EI NIC statically assigned, the two NIC's order in command line may make 
82586 NIC can't work in guest.
  command1: qemu-system-x86_64  -m 1024 -smp 2  -device pci-assign,host=0e:00.1 
-device pci-assign,host=0c:00.0 -net none -hda qcow-rhel6.img
  command2: qemu-system-x86_64  -m 1024 -smp 2  -device pci-assign,host=0c:00.0 
-device pci-assign,host=0e:00.1 -net none -hda qcow-rhel6.img
  Using command1 to create a guest, both two NICs works well in guest.
  While using command2 to create a guest, 82576(kawela) NIC 0c:00.0 cannot get 
IP in guest.
  BDF 0c:00.0 is a 82576(kawela) NIC, while BDF 0e:00.1 is 82572EI NIC.
  The only difference of the two command lines is the order of NICs assignment. 
  And only the 82576(kawela) NIC have this problem, the other one 82572EI 
always works well.
  And sriov VF doesn't have this issue.  A VF and a 82576 PF assigned to a 
guest always work well.
  I don't know the order of NIC assignment in qemu-system-x86_64 will make this 
difference in guest. Maybe it's a qemu bug ?

  Reproduce steps:
  ----------------
  1.pci-stub the two NIC
  2.create a guest: qemu-system-x86_64  -m 1024 -smp 2  -device
  pci-assign,host=0c:00.0 -device pci-assign,host=0e:00.1 -net none -hda
  qcow-rhel6.img
  (0c:00.0 is a 82576 NIC, and 0e:00.1 is another NIC).

  
  Current result:
  ----------------
  82576 PF and the other NIC in guest will work well regardless of what the 
order of assignment is.

  Expected result:
  ----------------

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