On Tue, 2022-05-03 at 20:04 +0700, Suravee Suthikulpanit wrote: > Maxim, > > On 5/3/22 12:13 AM, Maxim Levitsky wrote: > > > In the kvm/queue branch, I found a regression on nested SVM guest, where L2 guest cannot > > > launch. The bad commit is: > > > > > > commit a4cfff3f0f8c07f1f7873a82bdeb3995807dac8c (bisect) > > > Merge: 42dcbe7d8bac 8d5678a76689 > > > Author: Paolo Bonzini<pbonzini@xxxxxxxxxx> > > > Date: Fri Apr 8 12:43:40 2022 -0400 > > > > > > Merge branch 'kvm-older-features' into HEAD > > > > > > Merge branch for features that did not make it into 5.18: > > > > > > * New ioctls to get/set TSC frequency for a whole VM > > > > > > * Allow userspace to opt out of hypercall patching > > > > > > Nested virtualization improvements for AMD: > > > > > > * Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE, > > > nested vGIF) > > > > > > * Allow AVIC to co-exist with a nested guest running > > > > > > * Fixes for LBR virtualizations when a nested guest is running, > > > and nested LBR virtualization support > > > > > > * PAUSE filtering for nested hypervisors > > > > > > Guest support: > > > > > > * Decoupling of vcpu_is_preempted from PV spinlocks > > > > > > Signed-off-by: Paolo Bonzini<pbonzini@xxxxxxxxxx> > > > > > > I am still working on the bisect into the merge commits. > > > > > > Regards, > > > Suravee > > > > > What happens when the guest can't launch? It sure works for me for kvm/queue > > from yesterday. > > > > I'll test again tomorrow. > > I have bisected it to this commit: > > commit 74fd41ed16fd71725e69e2cb90b755505326c2e6 > Author: Maxim Levitsky <mlevitsk@xxxxxxxxxx> > Date: Tue Mar 22 19:40:47 2022 +0200 > > KVM: x86: nSVM: support PAUSE filtering when L0 doesn't intercept PAUSE > > Expose the pause filtering and threshold in the guest CPUID > and support PAUSE filtering when possible: > > - If the L0 doesn't intercept PAUSE (cpu_pm=on), then allow L1 to > have full control over PAUSE filtering. > > - if the L1 doesn't intercept PAUSE, use host values and update > the adaptive count/threshold even when running nested. > > - Otherwise always exit to L1; it is not really possible to merge > the fields correctly. It is expected that in this case, userspace > will not enable this feature in the guest CPUID, to avoid having the > guest update both fields pointlessly. > > Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> > Message-Id: <20220322174050.241850-4-mlevitsk@xxxxxxxxxx> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > I can revert this one or specify pause_filter_count=0 pause_filter_thresh=0, > and then I can boot the L2 guest. > > Regards, > Suravee > This is really wierd. Could you share the qemu command line for L1 and L2 guest, and as much as possible info on what happens when you boot L2? I tested latest kvm/queue and I don't see any issues with booting nested guest. Which hardware you test on? I test on Zen2 (3970X) mostly. How many vCPUs L2 has? Could you do a kvm trace of the L2, from L1, to see what it does prior to hang? Best regards, Maxim Levitsky
