While usually, restoring the smm state makes the KVM enter the nested guest thus a different vmcb (vmcb02 vs vmcb01), KVM should still mark it as dirty, since hardware can in theory cache multiple vmcbs.

Failure to do so, combined with lack of setting the nested_run_pending (which is fixed in the next patch), might make KVM re-enter vmcb01, which was just exited from, with completely different set of guest state registers (SMM vs non SMM) and without proper dirty bits set, which results in the CPU reusing stale IDTR pointer which leads to a guest shutdown on any interrupt.

On the real hardware this usually doesn't happen, but when running nested, L0's KVM does check and honour few dirty bits, causing this issue to happen.

This patch fixes boot of hyperv and SMM enabled windows VM running nested on KVM.

Signed-off-by: Maxim Levitsky mlevitsk@redhat.com Cc: stable@vger.kernel.org --- arch/x86/kvm/svm/svm.c | 2 ++ 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 995c203a62fd9..3f1d11e652123 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4267,6 +4267,8 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate) * Enter the nested guest now */

+ vmcb_mark_all_dirty(svm->vmcb01.ptr); + vmcb12 = map.hva; nested_copy_vmcb_control_to_cache(svm, &vmcb12->control); nested_copy_vmcb_save_to_cache(svm, &vmcb12->save);