On 20.09.2016 16:04, Cédric Le Goater wrote: > On 09/20/2016 02:24 PM, Cédric Le Goater wrote: >> On 09/20/2016 01:44 PM, Thomas Huth wrote: >>> Hi, >>> >>> when I try to run my guest in KVM-PR mode, current QEMU refuses to start: >>> >>> $ sudo qemu-system-ppc64 -M pseries,accel=kvm,kvm-type=PR \ >>> -nographic -vga none -cpu POWER8 >>> qemu: fatal: Unknown MMU model 851972 >>> >>> ... followed by a useless register dump. I've bisected the issue, and it >>> seems like the problem has been introduced by this commit here: >>> >>> commit 4322e8ced5aaac7191958f09622d199fe61e2d87 >>> ppc: Fix 64K pages support in full emulation >>> >>> Seems like KVM PR is using the "degraded" ISA variants (without the 1TB >>> segments), but the new POWERPC_MMU_64K flag has not been added to those. >>> Has this been done on purpose, or was this just by accident? >> >> The "degraded" architecture support has some history behind it : >> >> commit 126a79300971 added it >> commit aa4bb5875231 removed it. >> commit ba3ecda05e93 readded it. >> commit 4322e8ced5aa forgot about it again >> >>> I can make KVM PR working again with the following patch: >> >> I think this is correct. Let's wait for Ben to chime in :) > > So I confirm the bug and the fix. > > There are other issues after in the guest (kernel crashing). But I think > these are related to TM which is not supported in KVM-PR. I am not sure > where we are on that point.
There was a patch some months ago: https://lists.gnu.org/archive/html/qemu-ppc/2016-04/msg00046.html ... but I think it has never been included, as far as I can see. Thomas