KVM: nVMX: Support direct APIC access from L2

It's a pathological case, but still a valid one: If L1 disables APIC
virtualization and also allows L2 to directly write to the APIC page, we
have to forcibly enable APIC virtualization while in L2 if the in-kernel
APIC is in use.

This allows to run the direct interrupt test case in the vmx unit test
without x2APIC.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f90320b204a917c61fcbb16178d3d21287eccc2d..31eb5776d854e7dcecc4e0fb7255ce44e19b0432 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -7763,6 +7763,11 @@ static void prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12)
                        else
                                vmcs_write64(APIC_ACCESS_ADDR,
                                  page_to_phys(vmx->nested.apic_access_page));
+               } else if (vm_need_virtualize_apic_accesses(vmx->vcpu.kvm)) {
+                       exec_control |=
+                               SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+                       vmcs_write64(APIC_ACCESS_ADDR,
+                               page_to_phys(vcpu->kvm->arch.apic_access_page));
                }
 
                vmcs_write32(SECONDARY_VM_EXEC_CONTROL, exec_control);