[dpdk-dev] [PATCH v7 7/9] linuxapp/eal_vfio: honor iova mode before mapping

[Jonas Pfefferle1]

"dev" <dev-bounces at dpdk.org> wrote on 11/02/2017 11:26:57 AM:

> From: "Jonas Pfefferle1" <JPF at zurich.ibm.com>
> To: Thomas Monjalon <thomas at monjalon.net>
> Cc: aconole at redhat.com, anatoly.burakov at intel.com,
> bruce.richardson at intel.com, dev at dpdk.org, gaetan.rivet at 6wind.com,
> hemant.agrawal at nxp.com, jerin.jacob at caviumnetworks.com,
> maxime.coquelin at redhat.com, olivier.matz at 6wind.com, Santosh Shukla
> <santosh.shukla at caviumnetworks.com>,
> sergio.gonzalez.monroy at intel.com, shreyansh.jain at nxp.com,
> stephen at networkplumber.org, "Alexey Kardashevskiy" <aik at ozlabs.ru>
> Date: 11/02/2017 11:27 AM
> Subject: Re: [dpdk-dev] [PATCH v7 7/9] linuxapp/eal_vfio: honor iova
> mode before mapping
> Sent by: "dev" <dev-bounces at dpdk.org>
>
>
> Thomas Monjalon <thomas at monjalon.net> wrote on 11/02/2017 11:17:10 AM:
>
> > From: Thomas Monjalon <thomas at monjalon.net>
> > To: Jonas Pfefferle1 <JPF at zurich.ibm.com>
> > Cc: dev at dpdk.org, Santosh Shukla
> > <santosh.shukla at caviumnetworks.com>, jerin.jacob at caviumnetworks.com,
> > hemant.agrawal at nxp.com, olivier.matz at 6wind.com,
> > maxime.coquelin at redhat.com, sergio.gonzalez.monroy at intel.com,
> > bruce.richardson at intel.com, shreyansh.jain at nxp.com,
> > gaetan.rivet at 6wind.com, anatoly.burakov at intel.com,
> > stephen at networkplumber.org, aconole at redhat.com
> > Date: 11/02/2017 11:17 AM
> > Subject: Re: [dpdk-dev] [PATCH v7 7/9] linuxapp/eal_vfio: honor iova
> > mode before mapping
> >
> > Hi
> >
> > 26/10/2017 14:57, Jonas Pfefferle1:
> > >
> > > Hi @all
> > >
> > > I just stumbled upon this patch while testing on POWER. RTE_IOVA_VA
> will
> > > not work for the sPAPR code since the dma window size is currently
> > > determined by the physical address only.
> >
> > Is it    affecting POWER8?
>
> It is.
>
> >
> > > I'm preparing a patch to address this.
> >
> > Any news?
> > Can you use virtual addresses?
>
> After a long discussion with Alexey (CC) we came to the conclusion that
> with the current sPAPR iommu driver we cannot use virtual addresses since
> the iova is restricted to lay in the DMA window which itself is
restricted
> to physical RAM addresses resp. with the current code 0 to hotplug memory
> max. However, Alexey is working on a patch to lift this restriction on
the
> DMA window size which should allow us to do VA:VA mappings in the future.
> For now we should fall back to PA in the dynamic iova mode check. I will
> send an according patch later today.

I looked into this yesterday but I'm not sure what the right solution is
here.
At the time rte_pci_get_iommu_class is called we already know which IOMMU
types are supported because vfio_get_container_fd resp.
vfio_has_supported_extensions  has been called however we do not know which
one is going to be used (Decided later in vfio_setup_device resp.
vfio_set_iommu_type). We can choose a iova mode which is supported by all
types but if the modes are exclusive to the types we have to guess which
one is going to be used. Or let the user decide?

Thanks,
Jonas

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