KVM: VMX: Provide support for user space injected NMIs

This patch adds the required bits to the VMX side for user space
injected NMIs. As with the preexisting in-kernel irqchip support, the
CPU must provide the "virtual NMI" feature for proper tracking of the
NMI blocking state.

Based on the original patch by Sheng Yang.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 38d1385..f16a62c 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2360,6 +2360,7 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+       ++vcpu->stat.nmi_injections;
        if (vcpu->arch.rmode.active) {
                vmx->rmode.irq.pending = true;
                vmx->rmode.irq.vector = NMI_VECTOR;
@@ -2428,6 +2429,30 @@ static void do_interrupt_requests(struct kvm_vcpu *vcpu,
 {
        vmx_update_window_states(vcpu);
 
+       if (cpu_has_virtual_nmis()) {
+               if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
+                       if (vcpu->arch.nmi_window_open) {
+                               vcpu->arch.nmi_pending = false;
+                               vcpu->arch.nmi_injected = true;
+                       } else {
+                               enable_nmi_window(vcpu);
+                               return;
+                       }
+               }
+               if (vcpu->arch.nmi_injected) {
+                       vmx_inject_nmi(vcpu);
+                       if (vcpu->arch.nmi_pending
+                           || kvm_run->request_nmi_window)
+                               enable_nmi_window(vcpu);
+                       else if (vcpu->arch.irq_summary
+                                || kvm_run->request_interrupt_window)
+                               enable_irq_window(vcpu);
+                       return;
+               }
+               if (!vcpu->arch.nmi_window_open || kvm_run->request_nmi_window)
+                       enable_nmi_window(vcpu);
+       }
+
        if (vcpu->arch.interrupt_window_open) {
                if (vcpu->arch.irq_summary && !vcpu->arch.interrupt.pending)
                        kvm_do_inject_irq(vcpu);
@@ -2959,6 +2984,14 @@ static int handle_nmi_window(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
        ++vcpu->stat.nmi_window_exits;
 
+       /*
+        * If the user space waits to inject a NMI, exit as soon as possible
+        */
+       if (kvm_run->request_nmi_window && !vcpu->arch.nmi_pending) {
+               kvm_run->exit_reason = KVM_EXIT_NMI_WINDOW_OPEN;
+               return 0;
+       }
+
        return 1;
 }