Hi, Jason, > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Wednesday, September 29, 2021 8:59 PM > > On Wed, Sep 29, 2021 at 12:38:35AM +0000, Tian, Kevin wrote: > > > /* If set the driver must call iommu_XX as the first action in probe() or > > * before it attempts to do DMA > > */ > > bool suppress_dma_owner:1; > > It is not "attempts to do DMA" but more "operates the physical device > in any away" > > Not having ownership means another entity could be using user space > DMA to manipulate the device state and attack the integrity of the > kernel's programming of the device. > Does suppress_kernel_dma sounds better than suppress_dma_owner? We found the latter causing some confusion when doing internal code review. Somehow this flag represents "don't claim the kernel dma ownership during driver binding". suppress_dma_owner sounds the entire ownership is disabled... Another thing is about DMA_OWNER_SHARED, which is set to indicate no dma at all. Thinking more we feel that this flag is meaningless. Its sole purpose is to show compatibility to any USER/KERNEL ownership, and essentially the same semantics as a device which is not bound to any driver. So we plan to remove it then pci-stub just needs one line change to set the suppress flag. But want to check with you first in case any oversight. Thanks Kevin
