KVM: x86: Account for failing enable_irq_window for NMI window request

With VMX, enable_irq_window can now return -EBUSY, in which case an
immediate exit shall be requested before entering the guest. Account for
this also in enable_nmi_window which uses enable_irq_window in absence
of vnmi support, e.g.

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

4 files changed, 13 insertions, 13 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ec14b7245a4e..3741c653767c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -695,7 +695,7 @@ struct kvm_x86_ops {
         int (*nmi_allowed)(struct kvm_vcpu *vcpu);
         bool (*get_nmi_mask)(struct kvm_vcpu *vcpu);
         void (*set_nmi_mask)(struct kvm_vcpu *vcpu, bool masked);
-        void (*enable_nmi_window)(struct kvm_vcpu *vcpu);
+        int (*enable_nmi_window)(struct kvm_vcpu *vcpu);
         int (*enable_irq_window)(struct kvm_vcpu *vcpu);
         void (*update_cr8_intercept)(struct kvm_vcpu *vcpu, int tpr, int irr);
         int (*vm_has_apicv)(struct kvm *kvm);
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 7f896cbe717f..3421d5a92c06 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3649,13 +3649,13 @@ static int enable_irq_window(struct kvm_vcpu *vcpu)
         return 0;
 }
 
-static void enable_nmi_window(struct kvm_vcpu *vcpu)
+static int enable_nmi_window(struct kvm_vcpu *vcpu)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
 
         if ((svm->vcpu.arch.hflags & (HF_NMI_MASK | HF_IRET_MASK))
             == HF_NMI_MASK)
-                return; /* IRET will cause a vm exit */
+                return 0; /* IRET will cause a vm exit */
 
         /*
          * Something prevents NMI from been injected. Single step over possible
@@ -3664,6 +3664,7 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu)
         svm->nmi_singlestep = true;
         svm->vmcb->save.rflags |= (X86_EFLAGS_TF | X86_EFLAGS_RF);
         update_db_bp_intercept(vcpu);
+        return 0;
 }
 
 static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index e10217e99d2c..e53a5f7aa8a9 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4417,22 +4417,20 @@ static int enable_irq_window(struct kvm_vcpu *vcpu)
         return 0;
 }
 
-static void enable_nmi_window(struct kvm_vcpu *vcpu)
+static int enable_nmi_window(struct kvm_vcpu *vcpu)
 {
         u32 cpu_based_vm_exec_control;
 
-        if (!cpu_has_virtual_nmis()) {
-                enable_irq_window(vcpu);
-                return;
-        }
+        if (!cpu_has_virtual_nmis())
+                return enable_irq_window(vcpu);
+
+        if (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI)
+                return enable_irq_window(vcpu);
 
-        if (vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
-                enable_irq_window(vcpu);
-                return;
-        }
         cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
         cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_NMI_PENDING;
         vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
+        return 0;
 }
 
 static void vmx_inject_irq(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 96f914e828d4..94f35d22c5fb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5756,7 +5756,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 
                 /* enable NMI/IRQ window open exits if needed */
                 if (vcpu->arch.nmi_pending)
-                        kvm_x86_ops->enable_nmi_window(vcpu);
+                        req_immediate_exit =
+                                kvm_x86_ops->enable_nmi_window(vcpu) != 0;
                 else if (kvm_cpu_has_injectable_intr(vcpu) || req_int_win)
                         req_immediate_exit =
                                 kvm_x86_ops->enable_irq_window(vcpu) != 0;