On Tue, Feb 26, 2013 at 11:43 AM, Jan Kiszka <jan.kiszka@xxxxxx> wrote: > On 2013-02-26 15:11, Nadav Har'El wrote: >> On Thu, Feb 14, 2013, Nakajima, Jun wrote about "Re: [Bug 53611] New: nVMX: Add nested EPT": >>> We have started looking at the pataches first. But I couldn't >>> reproduce the results by simply applying the original patches to v3.6: >>> - L2 Ubuntu 12.04 (64-bit) (smp 2) >>> - L1 Ubuntu 12.04 (64-bit) KVM (smp 2) >>> - L0 Ubuntu 12.04 (64-bit)-based. kernel/KVM is v3.6 + patches (the >>> ones in nept-v2.tgz). >>> https://bugzilla.kernel.org/attachment.cgi?id=93101 >>> >>> Without the patches, the L2 guest works. With it, it hangs at boot >>> time (just black screen): >>> - EPT was detected by L1 KVM. >>> - UP L2 didn't help. >>> - Looks like it's looping at EPT_walk_add_generic at the same address in L0. >>> >>> Will take a closer look. It would be helpful if the test configuration >>> (e.g kernel/commit id used, L1/L2 guests) was documented as well. >> >> I sent the patches in August 1st, and they applied to commit >> ade38c311a0ad8c32e902fe1d0ae74d0d44bc71e from a week earlier. >> >> In most of my tests, L1 and L2 were old images - L1 had Linux 2.6.33, >> while L2 had Linux 2.6.28. In most of my tests both L1 and L2 were UP. >> >> I've heard another report of my patch not working with newer L1/L2 - >> the report said that L2 failed to boot (like you reported), and also >> that L1 became unstable (running anything in it gave a memory fault). >> So it is very likely that this code still has bugs - but since I already >> know of errors and holes that need to be plugged (see the announcement file >> together with the patches), it's not very surprising :( These patches >> definitely need some lovin', but it's easier than starting from scratch. > > FWIW, I'm playing with them on top of kvm-3.6-2 (second pull request for > 3.6) for a while. They work OK for my use case (static mapping) but > apparently lock up L2 when starting KVM on KVM, just as reported. I > didn't look into any details there, still busy with fixing other issues > like CR0/CR4 handling (which I came across while adding unrestricted > guest support on top of EPT). I have some updates on this. We rebased the patched to the latest KVM (L0). It turned out that the version of L1 KVM/Linux matters. At that time, actually I used v3.7 kernel for L1, and the L2 didn't work as I described above. If I use v3.5 or older for L1, L2 works with the EPT patches. So, I guess some changes made to v3.6 might have exposed a bug with the nested EPT patches or somewhere. We are looking at the changes to root-cause it. > > Given that I'm porting now patches between that branch and "next" back > and forth (I depend on EPT), it would be really great if someone > familiar with the KVM MMU (or enough time) could port the series to the > current git head. That would not solve remaining bugs but could trigger > more development, maybe also help me jumping into this. > > Thanks, > Jan > -- Jun Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
