On Mon, Feb 14, 2022 at 02:37:15PM +0100, Greg Kroah-Hartman wrote: > On Mon, Feb 14, 2022 at 09:18:53AM -0400, Jason Gunthorpe wrote: > > On Mon, Feb 14, 2022 at 10:59:50AM +0100, Greg Kroah-Hartman wrote: > > > > > > + if (ret && !drv->no_kernel_api_dma) > > > > + iommu_device_unuse_dma_api(dev); > > > > > > So you are now going to call this for every platform driver _unless_ > > > they set this flag? > > > > Yes, it is necessary because VFIO supports platform devices as well > > and needs to ensure security. Conflicting kernel driver attachements > > must be blocked, just like for PCI. > > A platform device shouldn't be using VFIO, but ugh, oh well, that ship > has sailed :( I don't know why you say that, but yes, this is was set long ago. > And stop it with the "security" mess, do not give people a false sense > of it here please. I'm confused by what you mean. This is all about what we tend to refer to as DMA security - meaning a device's DMA can be controled by a hostile environment and not impact the integrity of the kernel. Jason
