KVM: VMX: refactor/fix IRQ and NMI injectability determination

There are currently two ways in VMX to check if an IRQ or NMI can be
injected:
 - vmx_{nmi|irq}_enabled and
 - vcpu.arch.{nmi|interrupt}_window_open.
Even worse, one test (at the end of vmx_vcpu_run) uses an inconsistent,
likely incorrect logic.

This patch consolidates and unifies the tests over
{nmi|interrupt}_window_open as cache + vmx_update_window_states
for updating the cache content.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 21 insertions, 25 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8d0fc68fd4ec..f0866e1d20ee 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2362,6 +2362,21 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
                         INTR_TYPE_NMI_INTR | INTR_INFO_VALID_MASK | NMI_VECTOR);
 }
 
+static void vmx_update_window_states(struct kvm_vcpu *vcpu)
+{
+        u32 guest_intr = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
+
+        vcpu->arch.nmi_window_open =
+                !(guest_intr & (GUEST_INTR_STATE_STI |
+                                GUEST_INTR_STATE_MOV_SS |
+                                GUEST_INTR_STATE_NMI));
+
+        vcpu->arch.interrupt_window_open =
+                ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
+                 !(guest_intr & (GUEST_INTR_STATE_STI |
+                                 GUEST_INTR_STATE_MOV_SS)));
+}
+
 static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
 {
         int word_index = __ffs(vcpu->arch.irq_summary);
@@ -2374,15 +2389,12 @@ static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
         kvm_queue_interrupt(vcpu, irq);
 }
 
-
 static void do_interrupt_requests(struct kvm_vcpu *vcpu,
                                        struct kvm_run *kvm_run)
 {
         u32 cpu_based_vm_exec_control;
 
-        vcpu->arch.interrupt_window_open =
-                ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
-                 (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & 3) == 0);
+        vmx_update_window_states(vcpu);
 
         if (vcpu->arch.interrupt_window_open &&
             vcpu->arch.irq_summary && !vcpu->arch.interrupt.pending)
@@ -3075,22 +3087,6 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu)
         vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
 }
 
-static int vmx_nmi_enabled(struct kvm_vcpu *vcpu)
-{
-        u32 guest_intr = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
-        return !(guest_intr & (GUEST_INTR_STATE_NMI |
-                               GUEST_INTR_STATE_MOV_SS |
-                               GUEST_INTR_STATE_STI));
-}
-
-static int vmx_irq_enabled(struct kvm_vcpu *vcpu)
-{
-        u32 guest_intr = vmcs_read32(GUEST_INTERRUPTIBILITY_INFO);
-        return (!(guest_intr & (GUEST_INTR_STATE_MOV_SS |
-                               GUEST_INTR_STATE_STI)) &&
-                (vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF));
-}
-
 static void enable_intr_window(struct kvm_vcpu *vcpu)
 {
         if (vcpu->arch.nmi_pending)
@@ -3159,11 +3155,13 @@ static void vmx_intr_assist(struct kvm_vcpu *vcpu)
 {
         update_tpr_threshold(vcpu);
 
+        vmx_update_window_states(vcpu);
+
         if (cpu_has_virtual_nmis()) {
                 if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
                         if (vcpu->arch.interrupt.pending) {
                                 enable_nmi_window(vcpu);
-                        } else if (vmx_nmi_enabled(vcpu)) {
+                        } else if (vcpu->arch.nmi_window_open) {
                                 vcpu->arch.nmi_pending = false;
                                 vcpu->arch.nmi_injected = true;
                         } else {
@@ -3178,7 +3176,7 @@ static void vmx_intr_assist(struct kvm_vcpu *vcpu)
                 }
         }
         if (!vcpu->arch.interrupt.pending && kvm_cpu_has_interrupt(vcpu)) {
-                if (vmx_irq_enabled(vcpu))
+                if (vcpu->arch.interrupt_window_open)
                         kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu));
                 else
                         enable_irq_window(vcpu);
@@ -3339,9 +3337,7 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         if (vmx->rmode.irq.pending)
                 fixup_rmode_irq(vmx);
 
-        vcpu->arch.interrupt_window_open =
-                (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) &
-                 (GUEST_INTR_STATE_STI | GUEST_INTR_STATE_MOV_SS)) == 0;
+        vmx_update_window_states(vcpu);
 
         asm("mov %0, %%ds; mov %0, %%es" : : "r"(__USER_DS));
         vmx->launched = 1;