Messages in this thread | | | Date | Wed, 16 Aug 2023 14:16:58 +0000 | Subject | Re: 5.10.189 and 5.10.190 breaks nested virtualization | From | Sean Christopherson <> |
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On Wed, Aug 16, 2023, Dr. David Alan Gilbert wrote: > * Blair Strater (strater@protonmail.com) wrote: > > Per the request at https://lwn.net/Articles/940798/, I'm reaching out to > > let you know that this patch breaks nested virtualization on AMD > > processors. > > > > I've tested 5.10.189 and 5.10.190 on the "outer" virtual host, and both > > Debian 12 running libvirt, and Proxmox 7 as "inner" hosts. For Debian, the > > nested VM fails to start at all, and consumes the entirety of one CPU core. > > For Proxmox, 100-200MB/second of memory is allocated and never released, > > and also the guest fails to start. The problems go away when taking the > > outer host back to 5.10.188. > > > > The processor in question is a Ryzen 7 2700. The kernel revision for > > Proxmox is 5.15.108-1-pve, and the kernel revision for Debian 12 is > > 6.1.0-11-amd64. I've run into another person who can confirm that this bug > > also occurs in the 6.4 series, "somewhere between 6.4.3 and 6.4.9", 6.4.9 > > being the likely culprit. > > > > Please let me know if you need any other information. > > > > I apologize for bothering an entire mailing list, Greg's email bot told me to. > > cc'd in Vitaly (who I notice was working another regression bug in > the recent stables), and Sean (who I notice has an L2 patch in the > 5.10.189..190 set).
Does running with "spec_rstack_overflow=off" fix things for you? If so, can you then try testing the fix for the guest RFLAGS corruption[1]? It's a bit of a long shot, but I'm hoping we'll get lucky and all of these nested SVM errors[2] are just weird symptoms of branches going awry.
[1] https://lore.kernel.org/all/20230811155255.250835-1-seanjc@google.com [2] https://bugzilla.kernel.org/show_bug.cgi?id=217796
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