Re: [Xen-devel] dom0 as pvh boot problem

["Jan Beulich" <jbeulich@xxxxxxxx>]

>>> Elena Ufimtseva <ufimtseva@xxxxxxxxx> 01/02/15 7:32 PM >>>
>The last successful command is the reading status register of second IOMMU
>unit:
>
><snip from iommu_enable_translation() in
>./xen/drivers/passthrough/vtd/iommu.c>
>
>746:    sts = dmar_readl(iommu->reg, DMAR_GSTS_REG);
>747:    dmar_writel(iommu->reg, DMAR_GCMD_REG, sts | DMA_GCMD_TE);
>
></snip>
>
>After dmar_writel for second iommu the machine hangs.

That's rather odd - you say it doesn't even reach the IOMMU_WAIT_OP()
right after that? That would suggest a fault or other abnormal condition
raised by the translation enabling (i.e. some problem with the page tables,
albeit that should then have been a problem for the first IOMMU already).
Yet an eventual fault can't be delivered at that point due to interrupts being
disabled. Perhaps the VT-d maintainers (now Cc-ed) have some suggestion
as to what's going on or how to diagnose.

Jan


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