On Thu, 2014-04-10 at 09:19 -0700, Davidlohr Bueso wrote: > > > > > >> > > > > dmar: DMAR:[DMA Read] Request device [02:00.0] fault addr 7f61e000 > > > > That "Present bit in context entry is clear" fault means that we have > > not set up *any* mappings for this PCI device… on this IOMMU. > > > > > > Yes, specifically (finally done bisecting): > > > > > > > > commit 2e45528930388658603ea24d49cf52867b928d3e > > > > Author: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> > > > > Date: Wed Feb 19 14:07:36 2014 +0800 > > > > > > > > iommu/vt-d: Unify the way to process DMAR device scope array > > > > This commit is about how we decide which IOMMU a given PCI device is > > attached to. > > > > Thus, my first guess would be that we are quite happily setting up the > > requested DMA maps on the *wrong* IOMMU, and then taking faults when the > > device actually tries to do DMA. > > > > However, I'm not 100% convinced of that. The fault address looks > > suspiciously like a true physical address, not a virtual bus address of > > the type that we'd normally allocate for a dma_map_* operation. Those > > would start at 0xfffff000 and work downwards, typically. > > > > Do you have 'iommu=pt' on the kernel command line? > > No. > > > Can I see the full > > dmesg as this system boots, and also a copy of the DMAR table? > > Attaching a dmesg from one of the kernels that boots. It doesn't appear > to have much of the related information... It shows us that the address 0x7f61e000 is in an E820-reserved region, and that there's and RMRR covering that region for an unspecified PCI device, but that's going to be the hpsa. So if isn't just a simple case of us assigning this device to the wrong IOMMU, *perhaps* it's that we lose the RMRR when the driver takes control of the device. RMRRs are generally expected to be a boot-time thing, for things like legacy keyboard/mouse emulation via USB. Using them while the system is *active* is... horrid. We've often not quite handled that right. -- David Woodhouse Open Source Technology Centre David.Woodhouse@xxxxxxxxx Intel Corporation
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