On 28/06/2017 21:52, Graham Neville wrote: > Although not related to graphics card performance, there is definitely > another issue with regards to running KVM nested L2 guests when npt=1. > > Thought I'd mention this in case it helps with identifying performance > issues with NPT. > > I'm unable to start any L2 guests with KVM acceleration (--enable-kvm). > As soon as it attempts to bring up the L2 guest the L1 host crashes, L0 > host remains online. Nothing is printed in either L1 or L0's dmesg. > > My L0 is running Arch with 4.11.0-rc6, with qemu 2.8.0. I've tried > different L1 hosts (Ubuntu,Arch) and different kernels right to 4.12-rc5 > kernel, along with different qemu versions. > > This used to work fine with my Intel i7-4770s setup. > > With npt=0, L2 guests can start but performance is dier. Nested AMD needs some care. It's known, but time has been lacking... Paolo
