On Sat, Aug 10, 2019 at 11:46:21PM -0700, Ram Pai wrote: > On Sun, Aug 11, 2019 at 07:56:07AM +0200, Christoph Hellwig wrote: > > sev_active() is gone now in linux-next, at least as a global API. > > > > And once again this is entirely going in the wrong direction. The only > > way using the DMA API is going to work at all is if the device is ready > > for it. So we need a flag on the virtio device, exposed by the > > hypervisor (or hardware for hw virtio devices) that says: hey, I'm real, > > don't take a shortcut. > > > > And that means on power and s390 qemu will always have to set thos if > > you want to be ready for the ultravisor and co games. It's not like we > > haven't been through this a few times before, have we? > > > We have been through this so many times, but I dont think, we ever > understood each other. I have a fundamental question, the answer to > which was never clear. Here it is... > > If the hypervisor (hardware for hw virtio devices) does not mandate a > DMA API, why is it illegal for the driver to request, special handling > of its i/o buffers? Why are we associating this special handling to > always mean, some DMA address translation? Can't there be > any other kind of special handling needs, that has nothing to do with > DMA address translation?
I think the answer to that is, extend the DMA API to cover that special need then. And that's exactly what dma_addr_is_phys_addr is trying to do. > > -- > Ram Pai
