Re: 3.6-rc7 boot crash + bisection

From: Alex Williamson
Date: Wed Sep 26 2012 - 10:52:01 EST


On Wed, 2012-09-26 at 16:43 +0200, Roedel, Joerg wrote:
> Florian,
>
> On Wed, Sep 26, 2012 at 01:01:54AM +0200, Florian Dazinger wrote:
> > you're right, either "amd_iommu=off" or removing the audio card makes
> > the failure disappear. I will test the new BIOS rev. tomorrow.
>
> Can you please test this diff and report if it fixes the problem for
> you?
>
> Thanks.
>
> diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
> index b64502d..e89daf1 100644
> --- a/drivers/iommu/amd_iommu.c
> +++ b/drivers/iommu/amd_iommu.c
> @@ -266,7 +266,7 @@ static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
>
> static int iommu_init_device(struct device *dev)
> {
> - struct pci_dev *dma_pdev, *pdev = to_pci_dev(dev);
> + struct pci_dev *dma_pdev = NULL, *pdev = to_pci_dev(dev);
> struct iommu_dev_data *dev_data;
> struct iommu_group *group;
> u16 alias;
> @@ -293,7 +293,9 @@ static int iommu_init_device(struct device *dev)
> dev_data->alias_data = alias_data;
>
> dma_pdev = pci_get_bus_and_slot(alias >> 8, alias & 0xff);
> - } else
> + }
> +
> + if (dma_pdev == NULL)
> dma_pdev = pci_dev_get(pdev);
>
> /* Account for quirked devices */
>

Assuming this works, it may be ok as a 3.7 fix, but if there was
actually more than one device behind the alias we'd expose them as
separate iommu groups. I don't think that's what we want. Maybe it
should at least get a pr_warn. Thanks,

Alex

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