On Fri, 4 Dec 2020 16:44:14 +1100 David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> wrote: > The default behaviour for virtio devices is not to use the platforms normal > DMA paths, but instead to use the fact that it's running in a hypervisor > to directly access guest memory. That doesn't work if the guest's memory > is protected from hypervisor access, such as with AMD's SEV or POWER's PEF. > > So, if a securable guest memory mechanism is enabled, then apply the > iommu_platform=on option so it will go through normal DMA mechanisms. > Those will presumably have some way of marking memory as shared with > the hypervisor or hardware so that DMA will work. > > Signed-off-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx> > Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx> > --- > hw/core/machine.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
