On Wed, 15 Feb 2023 13:04:13 -0400 Jason Gunthorpe <jgg@xxxxxxxxxx> wrote: > On Wed, Feb 15, 2023 at 08:32:34AM -0700, Alex Williamson wrote: > > > We've discussed this with Paolo before and I believe the bar of proof > > is not very high. I suspect it's not a problem that the device itself > > is not yet accessible, so long as the user can prove they have the > > ability to access the device, such as access to a restricted file. In > > most cases this isn't going to turn on wbinvd anyway since DMA will be > > coherent. Thanks, > > Isn't that a second problem, we don't know if the device is coherent > until it is bound? I think this is already accounted for in the conversion to device level IOMMU ops, ie. device_iommu_capable() follows the dev->iommu->iommu_dev->ops, where for example intel_iommu_capable() is only looking at the capabilities of the IOMMU managing the device. We did some hand waving simplifications that was sufficient at some point, IIRC. Thanks, Alex
