On 11/11/16 16:27, Joerg Roedel wrote: > On Fri, Nov 11, 2016 at 04:17:37PM +0000, Robin Murphy wrote: >> In the original of_iommu_configure design, the thought was that an ops >> structure could be IOMMU-instance-specific (hence the later-removed >> "priv" member), so I suppose right now it is mostly a hangover from >> that. However, it's also what we initialise a device's fwspec with, so >> becomes important again if we're ever going to get past the limitations >> of buses-which-are-not-actually-buses[1]. > > Yeah, I discussed this with a few others at LPC. My current idea is to > tell the iommu-core which hardware-iommus exist in the system and a > seperate iommu_ops ptr for each of them. Then every struct device can > link to the iommu-instance it is translated by. Er, that sounds very much like a description of what we already have in 4.9-rc. Every struct device now has an iommu_fwspec which encapsulates both an iommu_ops pointer (which can perfectly well be per-instance if the IOMMU driver wants) and a place for the IOMMU-private data to replace the mess of archdata.iommu and driver-internal globals. > We are not there yet, but this will give you the same per-device > iommu-ops as implemented here. With those two patches I linked to, which make the bulk of the IOMMU core code per-device-ops-aware off the bat, I'd say we *are* already pretty much there. It's only iommu_domain_alloc() which needs a device-based alternative, and the non-of_xlate-based IOMMU drivers to either call iommu_fwspec_init() for themselves, or perhaps for x86 plumbing in DMAR/IVRS equivalents of the IORT parsing to the infrastructure provided by this series. Robin. -- 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
