linux-kernel - RE: VFs go missing with latest kernel

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Date:	Tue, 31 Jan 2012 22:58:39 +0000
From:	"Rose, Gregory V" <gregory.v.rose@...el.com>
To:	David Ahern <daahern@...co.com>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: RE: VFs go missing with latest kernel

> -----Original Message-----
> From: David Ahern [mailto:daahern@...co.com]
> Sent: Tuesday, January 31, 2012 2:54 PM
> To: Rose, Gregory V
> Cc: LKML
> Subject: VFs go missing with latest kernel
> 
> Hi
> 
> I built the kernel.git tree (3.3-rc1) and noticed that even numbered VFs
> go missing for the last 2 ports of a quad nic card.
> 
> This is the relevant output from lspci for the stock Fedora 14 kernel
> (2.6.35.14-106):
> 
> 07:00.0 Ethernet controller: Intel Corporation 82576 Gigabit Network
> Connection (rev 01)
> 07:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network
> Connection (rev 01)
> 08:10.0 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.1 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.2 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.3 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.4 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.5 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.6 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.7 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.0 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.1 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.2 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.3 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.4 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.5 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 
> 
> For the 3.3.0-rc1 kernel I get:
> 
> 07:00.0 Ethernet controller: Intel Corporation 82576 Gigabit Network
> Connection (rev 01)
> 07:00.1 Ethernet controller: Intel Corporation 82576 Gigabit Network
> Connection (rev 01)
> 08:10.1 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.3 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.5 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:10.7 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.1 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.3 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 08:11.5 Ethernet controller: Intel Corporation 82576 Virtual Function
> (rev 01)
> 
> Note that all of the even numbered VFs have disappeared. Accordingly,
> trying to launch the VM to which the VFs are assigned fails. git bisect
> pointed to this commit:
> 
> 0224d663063d542b3d829706f3fcbd0f640f19b3 is the first bad commit
> commit 0224d663063d542b3d829706f3fcbd0f640f19b3
> Author: Greg Rose <gregory.v.rose@...el.com>
> Date:   Fri Oct 14 02:57:14 2011 +0000
> 
>     igb: Check if subordinate VFs are assigned to virtual machines
> 
>     Kvm and the Xen pci-back driver will set a flag in the virtual
> function
>     pci device dev_flags when the VF is assigned to a guest VM.  Before
>     destroying subordinate VFs check to see if the flag is set and if so
>     skip the call to pci_disable_sriov() to avoid system crashes.
> 
>     Copy the maintainer for the Xen pci-back driver.  Also CC'ing
>     maintainers of all drivers found to call pci_disable_sriov().
> 
> 
> Sure enough reverting the patch on 3.3.0-rc1 makes the VFs visible again.
> 
> I am hitting some other problem trying to use the VF on 3.3.0-rc1 -- KVM
> fails the KVM_CAP_IOMMU check though the server has one (works fine with
> the older kernel) and it is built into the kernel. Debugging that
> problem now.

I'll see if I can reproduce that.  Is this all after a fresh boot with no unloading/reloading of the PF driver?

- Greg

> 
> David
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