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    SubjectRe: git-latest: kernel oops in IOMMU setup
    On Thu, Jan 08, 2009 at 12:05:38PM -0800, Dirk Hohndel wrote:
    >
    > latest git from Linus. On a Thinkpad x200s with VT-d enabled (if I
    > disable VT-d, this of course goes away).
    >
    > The oops happens very early during boot in device_to_iommu (called
    > from domain_context_mapping_one).
    >
    > Looking at the code dump and the disassembled function here's where
    > the error happens:
    >
    > static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn)
    > {
    > struct dmar_drhd_unit *drhd = NULL;
    > int i;
    >
    > for_each_drhd_unit(drhd) {
    > if (drhd->ignored)
    > continue;
    >
    > for (i = 0; i < drhd->devices_cnt; i++)
    > if (drhd->devices[i]->bus->number == bus &&
    > --> drhd->devices[0] is NULL
    > drhd->devices[i]->devfn == devfn)
    > return drhd->iommu;
    >
    >
    > Given how early this happens it's a little hard to provide logs, etc. I
    > literally used delay_boot=100 and wrote things down by hand (forgot my
    > digital camera) and then added printk's to verify).
    >
    > please let me know what other data I should collect.

    If you can, a back trace. Basically just need to know which caller
    is tripping over this. But there can't be that many callers and they
    are all in this file:
    0 intel-iommu.c device_to_iommu 431 static struct intel_iommu *device_to_iommu(u8 bus, u8 devfn)
    1 intel-iommu.c domain_context_mapping_on 1471 iommu = device_to_iommu(bus, devfn);
    2 intel-iommu.c domain_context_mapped 1593 iommu = device_to_iommu(pdev->bus->number, pdev->devfn);
    3 intel-iommu.c domain_remove_dev_info 1684 iommu = device_to_iommu(info->bus, info->devfn);
    4 intel-iommu.c vm_domain_remove_one_dev_ 2773 iommu = device_to_iommu(pdev->bus->number, pdev->devfn);
    5 intel-iommu.c vm_domain_remove_one_dev_ 2803 if (device_to_iommu(info->bus, info->devfn) == iommu)
    6 intel-iommu.c vm_domain_remove_all_dev_ 2836 iommu = device_to_iommu(info->bus, info->devfn);
    7 intel-iommu.c intel_iommu_attach_device 3023 iommu = device_to_iommu(pdev->bus->number, pdev->devfn);

    so it should be possible to figure out which one is called
    before the dev is setup. It's unlikely to be anything with
    "remove" in the name. :)

    My guess is it's intel_iommu_attach_device being called "too early".

    hth,
    grant


    hth,
    grant

    >
    > The system ran fine with the 2.6.28 release kernel.
    >
    > /D
    >
    > --
    > Dirk Hohndel
    > Intel Open Source Technology Center
    > --
    > To unsubscribe from this list: send the line "unsubscribe linux-pci" in
    > the body of a message to majordomo@vger.kernel.org
    > More majordomo info at http://vger.kernel.org/majordomo-info.html


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