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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ec14b72..3741c65 100644 (file)
--- 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 7f896cb..3421d5a 100644 (file)
--- 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 e10217e..e53a5f7 100644 (file)
--- 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 96f914e..94f35d2 100644 (file)
--- 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;