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From: Thomas Monjalon <thomas@monjalon.net>
Subject: Re: [PATCH v2] vfio: noiommu check error handling
Date: Tue, 07 Nov 2017 10:40:15 +0100
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To: Jonas Pfefferle1 <JPF@zurich.ibm.com>, anatoly.burakov@intel.com
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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?

Anatoly, any thought?