The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From a3535be731c2a343912578465021f50937f7b099 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini pbonzini@redhat.com Date: Sat, 16 May 2020 09:19:06 -0400 Subject: [PATCH] KVM: nSVM: fix condition for filtering async PF
Async page faults have to be trapped in the host (L1 in this case), since the APF reason was passed from L0 to L1 and stored in the L1 APF data page. This was completely reversed: the page faults were passed to the guest, a L2 hypervisor.
Cc: stable@vger.kernel.org Reviewed-by: Sean Christopherson sean.j.christopherson@intel.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index a89a166d1cb8..f4cd2d0cc360 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -880,8 +880,8 @@ int nested_svm_exit_special(struct vcpu_svm *svm) return NESTED_EXIT_HOST; break; case SVM_EXIT_EXCP_BASE + PF_VECTOR: - /* When we're shadowing, trap PFs, but not async PF */ - if (!npt_enabled && svm->vcpu.arch.apf.host_apf_reason == 0) + /* Trap async PF even if not shadowing */ + if (!npt_enabled || svm->vcpu.arch.apf.host_apf_reason) return NESTED_EXIT_HOST; break; default: