RE: [Xen-devel] SR-IOV problems - HVM cannot access network

["Rose, Gregory V" <gregory.v.rose@xxxxxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx [mailto:xen-devel-
> bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of David White
> Sent: Tuesday, March 01, 2011 11:32 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] SR-IOV problems - HVM cannot access network
> 
> Hi all,
> 
> I am having problems getting SR-IOV functions to work in my HVMs.  My
> hardware has VT-d support, and pci passthrough works fine for physical
> functions.  In a nutshell here is the current state:
> 
> Dom0 :  NICs are 2-port 82576.  I can get full network access using
> either PF or VF interfaces.
> HVM : PCI passthrough of physical functions work -- full network access
> HVM : PCI passthrough of virtual functions fail -- can send pkts but
> cannot receive.
> 
> The best lead I have right now is evident from the qemu logs.
> 
> when PF (04:00.0) is assigned to HVM:
> 
> pt_msix_init: get MSI-X table bar base fafbc000
> pt_msix_init: table_off = 0, total_entries = 10
> pt_msix_init: errno = 2
> pt_msix_init: mapping physical MSI-X table to 7f23a03d5000
> pt_msi_setup: msi mapped with pirq 37
> pci_intx: intx=1
> register_real_device: Real physical device 04:00.0 registered successfuly!
> IRQ type = MSI-INTx
> 
> when VF (04:10.2) is assigned to HVM:
> 
> pt_msix_init: get MSI-X table bar base fae24000
> pt_msix_init: table_off = 0, total_entries = 3
> pt_msix_init: errno = 2
> pt_msix_init: mapping physical MSI-X table to 7fc918846000
> register_real_device: Real physical device 04:10.2 registered successfuly!
> IRQ type = INTx
> 
> VFs don't seem to be using MSI/MSI-X interupts.  Does this indicate a
> problem?

Yes, this is absolutely a problem.  82576 virtual functions require MSI-X 
interrupt support to function properly.  You didn't mention what your guest OS 
is but the guest OS must support MSI-X interrupts.  Even if it does have MSI-X 
support the attempt to allocate the vectors may fail for some reason.  If that 
happens then the VF will not function correctly.

- Greg Rose
LAN Access Division
Intel Corp.


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