[dpdk-dev] Having troubles binding an SR-IOV VF to uio_pci_generic on Amazon instance

[Michael S. Tsirkin]

On Tue, Sep 29, 2015 at 02:46:16PM -0700, Stephen Hemminger wrote:
> On Tue, 29 Sep 2015 23:54:54 +0300
> "Michael S. Tsirkin" <mst at redhat.com> wrote:
> 
> > On Tue, Sep 29, 2015 at 07:41:09PM +0300, Vlad Zolotarov wrote:
> > > The security breach motivation u brought in "[RFC PATCH] uio:
> > > uio_pci_generic: Add support for MSI interrupts" thread seems a bit weak
> > > since one u let the userland access to the bar it may do any funny thing
> > > using the DMA engine of the device. This kind of stuff should be prevented
> > > using the iommu and if it's enabled then any funny tricks using MSI/MSI-X
> > > configuration will be prevented too.
> > > 
> > > I'm about to send the patch to main Linux mailing list. Let's continue this
> > > discussion there.
> > >   
> > 
> > Basically UIO shouldn't be used with devices capable of DMA.
> > Use VFIO for that (yes, this implies an emulated or PV IOMMU).
> > I don't think this can change.
> 
> Given there is no PV IOMMU and even if there was it would be too slow for DPDK
> use, I can't accept that. 

QEMU does allow emulating an iommu.  DPDK uses static mappings, so I
doubt it's speed matters at all.

Anyway, DPDK is doing polling all the time. I don't see why does it
insist on using interrupts to detect link up events. Just poll for that
too.

-- 
MST