Date: Wed, 30 Nov 2016 10:37:14 +0000
From: Will Deacon <will.deacon@arm.com>
To: Auger Eric <eric.auger@redhat.com>
Cc: eric.auger.pro@gmail.com, christoffer.dall@linaro.org,
        marc.zyngier@arm.com, robin.murphy@arm.com, alex.williamson@redhat.com,
        joro@8bytes.org, tglx@linutronix.de, jason@lakedaemon.net,
        linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
        drjones@redhat.com, linux-kernel@vger.kernel.org,
        pranav.sawargaonkar@gmail.com, iommu@lists.linux-foundation.org,
        punit.agrawal@arm.com, diana.craciun@nxp.com
Subject: Re: [RFC v3 00/10] KVM PCIe/MSI passthrough on ARM/ARM64 and IOVA
 reserved regions
Message-ID: <20161130103713.GB2724@arm.com>
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On Wed, Nov 30, 2016 at 10:49:33AM +0100, Auger Eric wrote:
> On 15/11/2016 14:09, Eric Auger wrote:
> > Following LPC discussions, we now report reserved regions through
> > iommu-group sysfs reserved_regions attribute file.
> > 
> > Reserved regions are populated through the IOMMU get_resv_region callback
> > (former get_dm_regions), now implemented by amd-iommu, intel-iommu and
> > arm-smmu.
> > 
> > The intel-iommu reports the [FEE0_0000h - FEF0_000h] MSI window as an
> > IOMMU_RESV_NOMAP reserved region.
> > 
> > arm-smmu reports the MSI window (arbitrarily located at 0x8000000 and
> > 1MB large) and the PCI host bridge windows.
> > 
> > The series integrates a not officially posted patch from Robin:
> > "iommu/dma: Allow MSI-only cookies".
> > 
> > This series currently does not address IRQ safety assessment.
> 
> I will respin this series taking into account Joerg's comment. Does
> anyone have additional comments or want to put forward some conceptual
> issues with the current direction and with this implementation?
> 
> As for the IRQ safety assessment, in a first step I would propose to
> remove the IOMMU_CAP_INTR_REMAP from arm-smmus and consider the
> assignment as unsafe. Any objection?

Well, yeah, because it's perfectly safe with GICv3.

Will