On Thu, Aug 17, 2017 at 05:56:23PM +0100, Robin Murphy wrote: > On 17/08/17 16:41, Joerg Roedel wrote: > > Okay, so just to check I got it right: Drivers do the above to check > > whether a device is managed by an IOMMU, and that crashes now because > > the 'group == NULL' check was removed? > > Indeed - the typical context is network descriptors that don't have > space to store the CPU virtual address of the buffer, so when a packet > arrives the driver has to work backwards from the DMA address, in this > sort of pattern: > > addr = desc[idx]->addr; > domain = iommu_get_domain_for_dev(dev); > if (domain) > addr = iommu_iova_to_phys(domain, addr) > buf = phys_to_virt(addr) > > (the GIC thing is similar but in reverse, with a physical address which > may or may not need replacing with an IOVA). Unless we were to change > the interface to be iommu_get_domain_for_group(), I think it makes sense > for it to remain valid to call for any device.
Okay, we should find a better solution for this at some point, but I applied the patch for now. Joerg