From 4020da3b9f0c7e403b654c43da989f8c0bb05b57 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Thu, 1 Apr 2021 17:38:14 +0300 Subject: [PATCH] KVM: x86: pending exceptions must not be blocked by an injected event Injected interrupts/nmi should not block a pending exception, but rather be either lost if nested hypervisor doesn't intercept the pending exception (as in stock x86), or be delivered in exitintinfo/IDT_VECTORING_INFO field, as a part of a VMexit that corresponds to the pending exception. The only reason for an exception to be blocked is when nested run is pending (and that can't really happen currently but still worth checking for). Signed-off-by: Maxim Levitsky Message-Id: <20210401143817.1030695-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/nested.c | 8 +++++++- arch/x86/kvm/vmx/nested.c | 10 ++++++++-- 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index fb46f90..8453c89 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -1062,7 +1062,13 @@ static int svm_check_nested_events(struct kvm_vcpu *vcpu) } if (vcpu->arch.exception.pending) { - if (block_nested_events) + /* + * Only a pending nested run can block a pending exception. + * Otherwise an injected NMI/interrupt should either be + * lost or delivered to the nested hypervisor in the EXITINTINFO + * vmcb field, while delivering the pending exception. + */ + if (svm->nested.nested_run_pending) return -EBUSY; if (!nested_exit_on_exception(svm)) return 0; diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c index fd334e4..c3ba842 100644 --- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -3806,9 +3806,15 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu) /* * Process any exceptions that are not debug traps before MTF. + * + * Note that only a pending nested run can block a pending exception. + * Otherwise an injected NMI/interrupt should either be + * lost or delivered to the nested hypervisor in the IDT_VECTORING_INFO, + * while delivering the pending exception. */ + if (vcpu->arch.exception.pending && !vmx_pending_dbg_trap(vcpu)) { - if (block_nested_events) + if (vmx->nested.nested_run_pending) return -EBUSY; if (!nested_vmx_check_exception(vcpu, &exit_qual)) goto no_vmexit; @@ -3825,7 +3831,7 @@ static int vmx_check_nested_events(struct kvm_vcpu *vcpu) } if (vcpu->arch.exception.pending) { - if (block_nested_events) + if (vmx->nested.nested_run_pending) return -EBUSY; if (!nested_vmx_check_exception(vcpu, &exit_qual)) goto no_vmexit; -- 2.7.4