On Wed, 20 Mar 2019 18:42:02 +0200 Maxim Levitsky <mlevitsk@xxxxxxxxxx> wrote: > On Wed, 2019-03-20 at 08:28 -0700, Bart Van Assche wrote: > > On Tue, 2019-03-19 at 16:41 +0200, Maxim Levitsky wrote: > > > * All guest memory is mapped into the physical nvme device > > > but not 1:1 as vfio-pci would do this. > > > This allows very efficient DMA. > > > To support this, patch 2 adds ability for a mdev device to listen on > > > guest's memory map events. > > > Any such memory is immediately pinned and then DMA mapped. > > > (Support for fabric drivers where this is not possible exits too, > > > in which case the fabric driver will do its own DMA mapping) > > > > Does this mean that all guest memory is pinned all the time? If so, are you > > sure that's acceptable? > I think so. The VFIO pci passthrough also pins all the guest memory. > SPDK also does this (pins and dma maps) all the guest memory. > > I agree that this is not an ideal solution but this is a fastest and simplest > solution possible. FWIW, the pinned memory request up through the vfio iommu driver count against the user's locked memory limits, if that's the concern. Thanks, Alex
