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From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v2] vfio: noiommu check error handling
Date: Fri, 12 Jan 2018 00:45:56 +0100
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To: Jonas Pfefferle1 <JPF@zurich.ibm.com>, anatoly.burakov@intel.com
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07/11/2017 10:50, Jonas Pfefferle1:
> Thomas Monjalon <thomas@monjalon.net> wrote on 11/07/2017 10:40:15 AM:
> 
> > From: Thomas Monjalon <thomas@monjalon.net>
> > To: Jonas Pfefferle1 <JPF@zurich.ibm.com>, anatoly.burakov@intel.com
> > Cc: dev@dpdk.org
> > Date: 11/07/2017 10:40 AM
> > Subject: Re: [dpdk-dev] [PATCH v2] vfio: noiommu check error handling
> >
> > 07/11/2017 10:05, Jonas Pfefferle1:
> > > Thomas Monjalon <thomas@monjalon.net> wrote on 11/06/2017 09:25:15 PM:
> > >
> > > > From: Thomas Monjalon <thomas@monjalon.net>
> > > > To: Jonas Pfefferle <jpf@zurich.ibm.com>, anatoly.burakov@intel.com
> > > > Cc: dev@dpdk.org
> > > > Date: 11/06/2017 09:55 PM
> > > > Subject: Re: [dpdk-dev] [PATCH v2] vfio: noiommu check error handling
> > > >
> > > > 31/10/2017 16:59, Jonas Pfefferle:
> > > > > Check and report errors on open/read in noiommu check.
> > > > >
> > > > > Signed-off-by: Jonas Pfefferle <jpf@zurich.ibm.com>
> > > >
> > > > I cannot decide to apply this patch as it does not explain what
> > > > it is fixing, and as it is not reviewed.
> > > >
> > >
> > > This patch adds error handling and logging to the noiommu check.
> > > Also, on older kernels when the noiommu_enable file does not exist it
> > > assumes noiommu is not enabled instead of returning -1.
> > > Note that in rte_pci_get_iommu_class (drivers/bus/pci/linux/pci.c)
> > > is the only usage of the function and it assumes return == 1:
> > > noiommu is enabled any other return value noiommu disabled, i.e.
> > > my code change does not change the behavior of this function.
> > > We might want to check for errors in rte_pci_get_iommu_class
> > > as well since assuming it is not enabled when we cannot open
> > > and read it might lead to iova == VA being used even if noiommu is
> > > enabled.
> > >
> > > All this comes back to what I proposed before: instead of
> > > the noiommu and PPC64 check we should decide which iova mode
> > > to use depending on the iommu types available.
> > > The type should be already available at the point where we
> > > decide on the iova type.
> > > (iommu types supported is checked by vfio_get_container_fd)
> >
> > Is there something urgent for 17.11?
> > Or can it be refined in 18.02?
> 
> Nothing urgent. We can refine this for 18.02.
> 
> > Anatoly, any thought?

Anatoly, Jonas, how do you want to proceed with this patch?