Groups > linux.kernel > #1519698

Re: Summary of LPC guest MSI discussion in Santa Fe

From	Joerg Roedel <joro@8bytes.org>
Newsgroups	linux.kernel
Subject	Re: Summary of LPC guest MSI discussion in Santa Fe
Date	2016-11-11 12:20 +0100
Message-ID	<sCi2d-3Bo-1@gated-at.bofh.it> (permalink)
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On Thu, Nov 10, 2016 at 10:46:01AM -0700, Alex Williamson wrote:
> In the case of x86, we know that DMA mappings overlapping the MSI
> doorbells won't be translated correctly, it's not a valid mapping for
> that range, and therefore the iommu driver backing the IOMMU API
> should describe that reserved range and reject mappings to it.

The drivers actually allow mappings to the MSI region via the IOMMU-API,
and I think it should stay this way also for other reserved ranges.
Address space management is done by the IOMMU-API user already (and has
to be done there nowadays), be it a DMA-API implementation which just
reserves these regions in its address space allocator or be it VFIO with
QEMU, which don't map RAM there anyway. So there is no point of checking
this again in the IOMMU drivers and we can keep that out of the
mapping/unmapping fast-path.

> For PCI devices userspace can examine the topology of the iommu group
> and exclude MMIO ranges of peer devices based on the BARs, which are
> exposed in various places, pci-sysfs as well as /proc/iomem.  For
> non-PCI or MSI controllers... ???

Right, the hardware resources can be examined. But maybe this can be
extended to also cover RMRR ranges? Then we would be able to assign
devices with RMRR mappings to guests.

	Joerg

Thread

[RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II) Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 2/8] iommu/iova: fix __alloc_and_insert_iova_range Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 4/8] iommu: Add a list of iommu_reserved_region in iommu_domain Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 5/8] vfio/type1: Introduce RESV_IOVA_RANGE capability Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 3/8] iommu/dma: Allow MSI-only cookies Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 7/8] iommu/vt-d: Implement add_reserved_regions callback Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 1/8] vfio: fix vfio_info_cap_add/shift Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  [RFC 6/8] iommu: Handle the list of reserved regions Eric Auger <eric.auger@redhat.com> - 2016-11-03 22:50 +0100
  Re: [RFC 0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II) Alex Williamson <alex.williamson@redhat.com> - 2016-11-04 05:10 +0100
    Summary of LPC guest MSI discussion in Santa Fe (was: Re: [RFC 0/8]  KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II)) Will Deacon <will.deacon@arm.com> - 2016-11-08 03:50 +0100
      Re: Summary of LPC guest MSI discussion in Santa Fe Auger Eric <eric.auger@redhat.com> - 2016-11-08 15:30 +0100
        Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-08 19:00 +0100
          Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-08 20:10 +0100
            Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-08 20:20 +0100
            Re: Summary of LPC guest MSI discussion in Santa Fe Auger Eric <eric.auger@redhat.com> - 2016-11-09 08:50 +0100
      Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-08 17:10 +0100
      Re: Summary of LPC guest MSI discussion in Santa Fe (was: Re: [RFC  0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II)) Christoffer Dall <christoffer.dall@linaro.org> - 2016-11-08 21:30 +0100
        Re: Summary of LPC guest MSI discussion in Santa Fe (was: Re: [RFC  0/8] KVM PCIe/MSI passthrough on ARM/ARM64 (Alt II)) Alex Williamson <alex.williamson@redhat.com> - 2016-11-09 00:40 +0100
          Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-09 04:00 +0100
            Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-09 18:10 +0100
              Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-09 20:00 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Christoffer Dall <christoffer.dall@linaro.org> - 2016-11-09 20:30 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-09 21:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Joerg Roedel <joro@8bytes.org> - 2016-11-10 15:50 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-10 18:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-09 21:40 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-09 23:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-09 23:30 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-10 00:30 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-10 00:40 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-10 01:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Auger Eric <eric.auger@redhat.com> - 2016-11-10 01:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-10 02:00 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Will Deacon <will.deacon@arm.com> - 2016-11-10 03:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Auger Eric <eric.auger@redhat.com> - 2016-11-10 12:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-10 18:50 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Joerg Roedel <joro@8bytes.org> - 2016-11-11 12:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-11 17:00 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Alex Williamson <alex.williamson@redhat.com> - 2016-11-11 17:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Joerg Roedel <joro@8bytes.org> - 2016-11-14 16:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-11 17:30 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-11 17:10 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Joerg Roedel <joro@8bytes.org> - 2016-11-10 16:00 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Robin Murphy <robin.murphy@arm.com> - 2016-11-09 21:20 +0100
                Re: Summary of LPC guest MSI discussion in Santa Fe Joerg Roedel <joro@8bytes.org> - 2016-11-10 16:30 +0100
      Re: Summary of LPC guest MSI discussion in Santa Fe Jon Masters <jcm@jonmasters.org> - 2016-11-21 07:00 +0100
        Re: Summary of LPC guest MSI discussion in Santa Fe Don Dutile <ddutile@redhat.com> - 2016-11-23 21:20 +0100

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