[PATCH 0/2] KVM: nVMX: Fix another case where KVM overrides VMX MSRs

From: Sean Christopherson
Date: Wed Nov 09 2022 - 19:57:52 EST


Fix another case where KVM overrides the VMX MSRs (well, just the one MSR)
during KVM_SET_CPUID. Similar to somewhat recent reverts

8805875aa473 ("Revert "KVM: nVMX: Do not expose MPX VMX controls when guest MPX disabled"")
9389d5774aca ("Revert "KVM: nVMX: Expose load IA32_PERF_GLOBAL_CTRL VM-{Entry,Exit} control"")

undo misguided KVM behavior where KVM overrides allowed-1 settings in the
secondary execution controls in response to changes to the guest's CPUID
model. To avoid breaking userspace that doesn't take ownership of the
VMX MSRs, go hands off if and only if userpace sets the MSR in question

Sean Christopherson (2):
KVM: nVMX: Don't muck with allowed sec exec controls on CPUID changes
KVM: selftests: Test KVM's handling of VMX's sec exec MSR on
KVM_SET_CPUID

arch/x86/kvm/vmx/capabilities.h | 1 +
arch/x86/kvm/vmx/nested.c | 3 +
arch/x86/kvm/vmx/vmx.c | 2 +-
.../selftests/kvm/include/x86_64/processor.h | 1 +
.../selftests/kvm/include/x86_64/vmx.h | 4 +-
.../selftests/kvm/x86_64/vmx_msrs_test.c | 92 +++++++++++++++++++
6 files changed, 100 insertions(+), 3 deletions(-)


base-commit: d663b8a285986072428a6a145e5994bc275df994
--
2.38.1.431.g37b22c650d-goog