On Thu, 16 May 2019 15:42:45 +0200 Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > On Thu, 16 May 2019 08:32:28 +0200 > Cornelia Huck <cohuck@xxxxxxxxxx> wrote: > > > On Wed, 15 May 2019 23:08:17 +0200 > > Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > > > > > On Tue, 14 May 2019 10:47:34 -0400 > > > "Jason J. Herne" <jjherne@xxxxxxxxxxxxx> wrote: > > > > > > Are we > > > > worried that virtio data structures are going to be a burden on the 31-bit address space? > > > > > > > > > > > > > > That is a good question I can not answer. Since it is currently at least > > > a page per queue (because we use dma direct, right Mimu?), I am concerned > > > about this. > > > > > > Connie, what is your opinion? > > > > Yes, running into problems there was one of my motivations for my > > question. I guess it depends on the number of devices and how many > > queues they use. The problem is that it affects not only protected virt > > guests, but all guests. > > > > Unless things are about to change only devices that have > VIRTIO_F_IOMMU_PLATFORM are affected. So it does not necessarily affect > not protected virt guests. (With prot virt we have to use > VIRTIO_F_IOMMU_PLATFORM.) > > If it were not like this, I would be much more worried. If we go forward with this approach, documenting this side effect of VIRTIO_F_IOMMU_PLATFORM is something that needs to happen. > > @Mimu: Could you please discuss this problem with the team? It might be > worth considering to go back to the design of the RFC (i.e. cio/ccw stuff > allocated from a common cio dma pool which gives you 31 bit addressable > memory, and 64 bit dma mask for a ccw device of a virtio device). > > Regards, > Halil >
