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    SubjectRe: [PATCH v4 12/15] iommu/vt-d: Cleanup get_valid_domain_for_dev()
    On Fri, 2 Aug 2019 15:17:45 +0800
    Lu Baolu <baolu.lu@linux.intel.com> wrote:

    > Hi Alex,
    >
    > Thanks for reporting this. I will try to find a machine with a
    > pcie-to-pci bridge and get this issue fixed. I will update you
    > later.

    Further debug below...

    > On 8/2/19 9:30 AM, Alex Williamson wrote:
    > > DMAR: No ATSR found
    > > DMAR: dmar0: Using Queued invalidation
    > > DMAR: dmar1: Using Queued invalidation
    > > pci 0000:00:00.0: DMAR: Software identity mapping
    > > pci 0000:00:01.0: DMAR: Software identity mapping
    > > pci 0000:00:02.0: DMAR: Software identity mapping
    > > pci 0000:00:16.0: DMAR: Software identity mapping
    > > pci 0000:00:1a.0: DMAR: Software identity mapping
    > > pci 0000:00:1b.0: DMAR: Software identity mapping
    > > pci 0000:00:1c.0: DMAR: Software identity mapping
    > > pci 0000:00:1c.5: DMAR: Software identity mapping
    > > pci 0000:00:1c.6: DMAR: Software identity mapping
    > > pci 0000:00:1c.7: DMAR: Software identity mapping
    > > pci 0000:00:1d.0: DMAR: Software identity mapping
    > > pci 0000:00:1f.0: DMAR: Software identity mapping
    > > pci 0000:00:1f.2: DMAR: Software identity mapping
    > > pci 0000:00:1f.3: DMAR: Software identity mapping
    > > pci 0000:01:00.0: DMAR: Software identity mapping
    > > pci 0000:01:00.1: DMAR: Software identity mapping
    > > pci 0000:03:00.0: DMAR: Software identity mapping
    > > pci 0000:04:00.0: DMAR: Software identity mapping
    > > DMAR: Setting RMRR:
    > > pci 0000:00:02.0: DMAR: Setting identity map [0xbf800000 - 0xcf9fffff]
    > > pci 0000:00:1a.0: DMAR: Setting identity map [0xbe8d1000 - 0xbe8dffff]
    > > pci 0000:00:1d.0: DMAR: Setting identity map [0xbe8d1000 - 0xbe8dffff]
    > > DMAR: Prepare 0-16MiB unity mapping for LPC
    > > pci 0000:00:1f.0: DMAR: Setting identity map [0x0 - 0xffffff]
    > > pci 0000:00:00.0: Adding to iommu group 0
    > > pci 0000:00:00.0: Using iommu direct mapping
    > > pci 0000:00:01.0: Adding to iommu group 1
    > > pci 0000:00:01.0: Using iommu direct mapping
    > > pci 0000:00:02.0: Adding to iommu group 2
    > > pci 0000:00:02.0: Using iommu direct mapping
    > > pci 0000:00:16.0: Adding to iommu group 3
    > > pci 0000:00:16.0: Using iommu direct mapping
    > > pci 0000:00:1a.0: Adding to iommu group 4
    > > pci 0000:00:1a.0: Using iommu direct mapping
    > > pci 0000:00:1b.0: Adding to iommu group 5
    > > pci 0000:00:1b.0: Using iommu direct mapping
    > > pci 0000:00:1c.0: Adding to iommu group 6
    > > pci 0000:00:1c.0: Using iommu direct mapping
    > > pci 0000:00:1c.5: Adding to iommu group 7
    > > pci 0000:00:1c.5: Using iommu direct mapping
    > > pci 0000:00:1c.6: Adding to iommu group 8
    > > pci 0000:00:1c.6: Using iommu direct mapping
    > > pci 0000:00:1c.7: Adding to iommu group 9

    Note that group 9 contains device 00:1c.7

    > > pci 0000:00:1c.7: Using iommu direct mapping

    I'm booted with iommu=pt, so the domain type is IOMMU_DOMAIN_PT

    > > pci 0000:00:1d.0: Adding to iommu group 10
    > > pci 0000:00:1d.0: Using iommu direct mapping
    > > pci 0000:00:1f.0: Adding to iommu group 11
    > > pci 0000:00:1f.0: Using iommu direct mapping
    > > pci 0000:00:1f.2: Adding to iommu group 11
    > > pci 0000:00:1f.3: Adding to iommu group 11
    > > pci 0000:01:00.0: Adding to iommu group 1
    > > pci 0000:01:00.1: Adding to iommu group 1
    > > pci 0000:03:00.0: Adding to iommu group 12
    > > pci 0000:03:00.0: Using iommu direct mapping
    > > pci 0000:04:00.0: Adding to iommu group 13
    > > pci 0000:04:00.0: Using iommu direct mapping
    > > pci 0000:05:00.0: Adding to iommu group 9

    05:00.0 is downstream of 00:1c.7 and in the same group. As above, the
    domain is type IOMMU_DOMAIN_IDENTITY, so we take the following branch:

    } else {
    if (device_def_domain_type(dev) == IOMMU_DOMAIN_DMA) {

    Default domain type is IOMMU_DOMAIN_DMA because of the code block in
    device_def_domain_type() handling bridges to conventional PCI and
    conventional PCI endpoints.

    ret = iommu_request_dma_domain_for_dev(dev);

    This fails in request_default_domain_for_dev() because there's more
    than one device in the group.

    if (ret) {
    dmar_domain->flags |= DOMAIN_FLAG_LOSE_CHILDREN;
    if (!get_private_domain_for_dev(dev)) {

    With this commit, this now returns NULL because find_domain() does find
    a domain, the same one we found before this code block.

    dev_warn(dev,
    "Failed to get a private domain.\n");
    return -ENOMEM;
    }

    So the key factors are that I'm booting with iommu=pt and I have a
    PCIe-to-PCI bridge grouped with its parent root port. The bridge
    wants an IOMMU_DOMAIN_DMA, but the group domain is already of type
    IOMMU_DOMAIN_IDENTITY. A temporary workaround is to not use
    passthrough mode, but this is a regression versus previous kernels.
    Thanks,

    Alex

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