Re: [dpdk-dev] [PATCH] vfio: make container open error non-fatal

[Neil Horman <nhorman@tuxdriver.com>]

On Mon, Jun 16, 2014 at 10:30:54PM +0000, Richardson, Bruce wrote:
> The below patch is the quickest fix I found to make my applications work again, but I'm not sure it's the best solution. Can anyone else offer other suggestions to improve this?
> 
> > -----Original Message-----
> > From: Richardson, Bruce
> > Sent: Monday, June 16, 2014 3:29 PM
> > To: dev@dpdk.org
> > Cc: Richardson, Bruce
> > Subject: [PATCH] vfio: make container open error non-fatal
> > 
> > When setting up an app to run using the uio driver, errors caused by
> > VFIO failures should not abruptly cause the app to fail.
> > 
> > Example: on a board with 8 ports bound to igb_uio module, and no VFIO
> > configuration, a testpmd run currently fails with:
> > 
> > EAL:   cannot open VFIO container!
> > EAL:   0000:04:00.0 cannot open VFIO container!
> > EAL: Error - exiting with code: 1
> >   Cause: Requested device 0000:04:00.0 cannot be used
> > 
> > With this patch applied, the problem with VFIO is ignored and testpmd
> > successfully starts up - with ignored errors with vfio - as below:
> > 
> > EAL: PCI device 0000:04:00.0 on NUMA socket 0
> > EAL:   probe driver: 8086:1521 rte_igb_pmd
> > EAL:   unknown IOMMU driver!
> > EAL:   0000:04:00.0 cannot open VFIO container!
> > EAL:   0000:04:00.0 not managed by UIO driver, skipping
> > <...scan results for other ports skipped...>
> > EAL: PCI device 0000:8e:00.0 on NUMA socket 1
> > EAL:   probe driver: 8086:154a rte_ixgbe_pmd
> > EAL:   unknown IOMMU driver!
> > EAL:   0000:8e:00.0 cannot open VFIO container!
> > EAL:   PCI memory mapped at 0x7ff4ff5fa000
> > EAL:   PCI memory mapped at 0x7ff4ff5f6000
> > EAL: PCI device 0000:8e:00.1 on NUMA socket 1
> > EAL:   probe driver: 8086:154a rte_ixgbe_pmd
> > EAL:   unknown IOMMU driver!
> > EAL:   0000:8e:00.1 cannot open VFIO container!
> > EAL:   PCI memory mapped at 0x7ff4ff4f6000
> > EAL:   PCI memory mapped at 0x7ff4ff4f2000
> > Interactive-mode selected
> > Configuring Port 0 (socket 0)
> > <...other 7 ports ...>
> > Checking link statuses...
> > Port 0 Link Up - speed 10000 Mbps - full-duplex
> > Port 1 Link Down
> > Port 2 Link Up - speed 10000 Mbps - full-duplex
> > Port 3 Link Down
> > Port 4 Link Up - speed 10000 Mbps - full-duplex
> > Port 5 Link Down
> > Port 6 Link Up - speed 10000 Mbps - full-duplex
> > Port 7 Link Down
> > Done
> > testpmd>
> > 
> > This issue is introduced by the VFIO patch set addition, specifically
> > commit ff0b67d1.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> >  lib/librte_eal/linuxapp/eal/eal_pci_vfio.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > index 4de6061..4af38f6 100644
> > --- a/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > +++ b/lib/librte_eal/linuxapp/eal/eal_pci_vfio.c
> > @@ -528,7 +528,7 @@ pci_vfio_map_resource(struct rte_pci_device *dev)
> >  		int vfio_container_fd = pci_vfio_get_container_fd();
> >  		if (vfio_container_fd < 0) {
> >  			RTE_LOG(ERR, EAL, "  %s cannot open VFIO
> > container!\n", pci_addr);
> > -			return -1;
> > +			return 1;
> >  		}
> > 
> >  		vfio_cfg.vfio_container_fd = vfio_container_fd;
> > --
> > 1.9.3
> 
> 

I think it would be preferable to convert the pci_vfio_get_container_fd function
to return not -1, but some -ERRNO value, so that the caller can differentiate
between fatal and non-fatal errors (for instance, not having any vfio container
seems non-fatal, but having one with an incompatible api version may be
unworkable.

Neil