Debugging VM-Enter failures has been the bane of my existence for years. Seeing KVM's VMCS dump format pop up on a console triggers a Pavlovian response of swear words and sighs. As KVM's coverage of VM-Enter checks improve, so too do the odds of being able to triage/debug a KVM (or any other hypervisor) bug by running the bad KVM build as an L1 guest. Improve support for using KVM to debug a buggy VMM by adding tracepoints to capture the basic gist of a VM-Enter failure so that extracting said information from KVM doesn't require attaching a debugger or modifying L0 KVM to manually log failures. The captured information is by no means complete or perfect, e.g. I'd love to capture *exactly* why a consistency check failed, but logging that level of detail would require invasive code changes and might even act as a deterrent to adding more checks in KVM. v2: Rebase to kvm/queue. Sean Christopherson (2): KVM: nVMX: add tracepoint for failed nested VM-Enter KVM: nVMX: trace nested VM-Enter failures detected by H/W arch/x86/include/asm/vmx.h | 14 ++ arch/x86/kvm/trace.h | 22 +++ arch/x86/kvm/vmx/nested.c | 271 +++++++++++++++++++------------------ arch/x86/kvm/x86.c | 1 + 4 files changed, 180 insertions(+), 128 deletions(-) -- 2.22.0
