[5.19,161/717] KVM: nVMX: Unconditionally purge queued/injected events on nested "exit"
Commit Message
Greg KH
Oct. 22, 2022, 7:20 a.m. UTC
From: Sean Christopherson <seanjc@google.com> commit d953540430c5af57f5de97ea9e36253908204027 upstream. Drop pending exceptions and events queued for re-injection when leaving nested guest mode, even if the "exit" is due to VM-Fail, SMI, or forced by host userspace. Failure to purge events could result in an event belonging to L2 being injected into L1. This _should_ never happen for VM-Fail as all events should be blocked by nested_run_pending, but it's possible if KVM, not the L1 hypervisor, is the source of VM-Fail when running vmcs02. SMI is a nop (barring unknown bugs) as recognition of SMI and thus entry to SMM is blocked by pending exceptions and re-injected events. Forced exit is definitely buggy, but has likely gone unnoticed because userspace probably follows the forced exit with KVM_SET_VCPU_EVENTS (or some other ioctl() that purges the queue). Fixes: 4f350c6dbcb9 ("kvm: nVMX: Handle deferred early VMLAUNCH/VMRESUME failure properly") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Jim Mattson <jmattson@google.com> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> Link: https://lore.kernel.org/r/20220830231614.3580124-2-seanjc@google.com Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/kvm/vmx/nested.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)
--- a/arch/x86/kvm/vmx/nested.c +++ b/arch/x86/kvm/vmx/nested.c @@ -4264,14 +4264,6 @@ static void prepare_vmcs12(struct kvm_vc nested_vmx_abort(vcpu, VMX_ABORT_SAVE_GUEST_MSR_FAIL); } - - /* - * Drop what we picked up for L2 via vmx_complete_interrupts. It is - * preserved above and would only end up incorrectly in L1. - */ - vcpu->arch.nmi_injected = false; - kvm_clear_exception_queue(vcpu); - kvm_clear_interrupt_queue(vcpu); } /* @@ -4611,6 +4603,17 @@ void nested_vmx_vmexit(struct kvm_vcpu * WARN_ON_ONCE(nested_early_check); } + /* + * Drop events/exceptions that were queued for re-injection to L2 + * (picked up via vmx_complete_interrupts()), as well as exceptions + * that were pending for L2. Note, this must NOT be hoisted above + * prepare_vmcs12(), events/exceptions queued for re-injection need to + * be captured in vmcs12 (see vmcs12_save_pending_event()). + */ + vcpu->arch.nmi_injected = false; + kvm_clear_exception_queue(vcpu); + kvm_clear_interrupt_queue(vcpu); + vmx_switch_vmcs(vcpu, &vmx->vmcs01); /* Update any VMCS fields that might have changed while L2 ran */