linux-kernel - Re: [RFC v3 00/10] KVM PCIe/MSI passthrough on ARM/ARM64 and IOVA reserved regions

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Date:   Wed, 30 Nov 2016 10:49:33 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, christoffer.dall@...aro.org,
        marc.zyngier@....com, robin.murphy@....com,
        alex.williamson@...hat.com, will.deacon@....com, joro@...tes.org,
        tglx@...utronix.de, jason@...edaemon.net,
        linux-arm-kernel@...ts.infradead.org
Cc:     kvm@...r.kernel.org, drjones@...hat.com,
        linux-kernel@...r.kernel.org, pranav.sawargaonkar@...il.com,
        iommu@...ts.linux-foundation.org, punit.agrawal@....com,
        diana.craciun@....com
Subject: Re: [RFC v3 00/10] KVM PCIe/MSI passthrough on ARM/ARM64 and IOVA
 reserved regions

Hi,

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?

Thanks

Eric


> Best Regards
> 
> Eric
> 
> Git: complete series available at
> https://github.com/eauger/linux/tree/v4.9-rc5-reserved-rfc-v3
> 
> History:
> RFC v2 -> v3:
> - switch to an iommu-group sysfs API
> - use new dummy allocator provided by Robin
> - dummy allocator initialized by vfio-iommu-type1 after enumerating
>   the reserved regions
> - at the moment ARM MSI base address/size is left unchanged compared
>   to v2
> - we currently report reserved regions and not usable IOVA regions as
>   requested by Alex
> 
> RFC v1 -> v2:
> - fix intel_add_reserved_regions
> - add mutex lock/unlock in vfio_iommu_type1
> 
> 
> Eric Auger (10):
>   iommu/dma: Allow MSI-only cookies
>   iommu: Rename iommu_dm_regions into iommu_resv_regions
>   iommu: Add new reserved IOMMU attributes
>   iommu: iommu_alloc_resv_region
>   iommu: Do not map reserved regions
>   iommu: iommu_get_group_resv_regions
>   iommu: Implement reserved_regions iommu-group sysfs file
>   iommu/vt-d: Implement reserved region get/put callbacks
>   iommu/arm-smmu: Implement reserved region get/put callbacks
>   vfio/type1: Get MSI cookie
> 
>  drivers/iommu/amd_iommu.c       |  20 +++---
>  drivers/iommu/arm-smmu.c        |  52 +++++++++++++++
>  drivers/iommu/dma-iommu.c       | 116 ++++++++++++++++++++++++++-------
>  drivers/iommu/intel-iommu.c     |  50 ++++++++++----
>  drivers/iommu/iommu.c           | 141 ++++++++++++++++++++++++++++++++++++----
>  drivers/vfio/vfio_iommu_type1.c |  26 ++++++++
>  include/linux/dma-iommu.h       |   7 ++
>  include/linux/iommu.h           |  49 ++++++++++----
>  8 files changed, 391 insertions(+), 70 deletions(-)
>