On Fri, Nov 11, 2011 at 05:26:44PM -0700, Alex Williamson wrote: > domain_update_iommu_coherency() currently defaults to setting domains > as coherent when the domain is not attached to any iommus. This > allows for a window in domain_context_mapping_one() where such a > domain can update context entries non-coherently, and only after > update the domain capability to clear iommu_coherency. > > This can be seen using KVM device assignment on VT-d systems that > do not support coherency in the ecap register. When a device is > added to a guest, a domain is created (iommu_coherency = 0), the > device is attached, and ranges are mapped. If we then hot unplug > the device, the coherency is updated and set to the default (1) > since no iommus are attached to the domain. A subsequent attach > of a device makes use of the same dmar domain (now marked coherent) > updates context entries with coherency enabled, and only disables > coherency as the last step in the process. > > To fix this, switch domain_update_iommu_coherency() to use the > safer, non-coherent default for domains not attached to iommus. > > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > Tested-by: Donald Dutile <ddutile@xxxxxxxxxx> > Acked-by: Donald Dutile <ddutile@xxxxxxxxxx> > Acked-by: Chris Wright <chrisw@xxxxxxxxxxxx> Applied, thanks. -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
