Am Mittwoch, 11. April 2012, 17:38:14 schrieb Nadav Har'El: > On Wed, Apr 11, 2012, Guido Winkelmann wrote about "Nested virtualization on > Intel does not work - second level freezes when third level is starting": > > Nested virtualization on Intel does not work for me with qemu-kvm. As soon > > as the third layer OS (second virtualised) is starting the Linux kernel, > > the entire second layer freezes up. The last thing I can see console of > > the third > Hi, > > From your description, I understand that "ordinary" (2-level) nested > virtualization working for you (host, guest and 2nd-level guest), and it's > the third nesting level (guest's guest's guest) which is broken?
No, even 2-level nesting is broken. I can run Host->Guest, but not Host->Guest->2nd Level Guest. I haven't even tried with a third virtualized level. I suppose the misunderstanding happened because, in my original mail, I was counting the host as one level. > This is the second report of this nature in a week (see the previous > report in https://bugzilla.kernel.org/show_bug.cgi?id=43068 - the > details there are different), so I guess I'll need to find the time > to give this issue some attention. L3 did work for me when the nested > VMX patches were included in KVM, so either something broke since, or > (perhaps more likely) your slightly different setups have features that > my setup didn't. > > But in any case, like I explain in the aforementioned URL, even if L3 would > work, in the current implementation it would be extremenly slow - perhaps to > the point of being unusable (I think you saw this with grub performance in > L3). So I wonder if you'd really want to use it, even if it worked... Just > curious, what were you thinking of doing with L3? I was trying to test network setups that involve migrating VMs between hosts a lot, and I was hoping to be able to use only one physical server for that. As I said, I really only need one level of nesting for that (i.e. two levels of virtualization, three levels of OSes when counting the host). Guido -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
