KVM: Do not re-execute INTn instruction.

Re-inject event instead. This is what Intel suggest. Also use correct
instruction length when re-injecting soft fault/interrupt.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

4 files changed, 43 insertions, 17 deletions

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 1315ce025e57..377c4f17d170 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2310,13 +2310,13 @@ static void svm_queue_irq(struct kvm_vcpu *vcpu, unsigned nr)
                 SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_INTR;
 }
 
-static void svm_set_irq(struct kvm_vcpu *vcpu, int irq)
+static void svm_set_irq(struct kvm_vcpu *vcpu)
 {
         struct vcpu_svm *svm = to_svm(vcpu);
 
         nested_svm_intr(svm);
 
-        svm_queue_irq(vcpu, irq);
+        svm_queue_irq(vcpu, vcpu->arch.interrupt.nr);
 }
 
 static void update_cr8_intercept(struct kvm_vcpu *vcpu, int tpr, int irr)
@@ -2418,7 +2418,7 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
         case SVM_EXITINTINFO_TYPE_EXEPT:
                 /* In case of software exception do not reinject an exception
                    vector, but re-execute and instruction instead */
-                if (vector == BP_VECTOR || vector == OF_VECTOR)
+                if (kvm_exception_is_soft(vector))
                         break;
                 if (exitintinfo & SVM_EXITINTINFO_VALID_ERR) {
                         u32 err = svm->vmcb->control.exit_int_info_err;
@@ -2428,7 +2428,7 @@ static void svm_complete_interrupts(struct vcpu_svm *svm)
                         kvm_queue_exception(&svm->vcpu, vector);
                 break;
         case SVM_EXITINTINFO_TYPE_INTR:
-                kvm_queue_interrupt(&svm->vcpu, vector);
+                kvm_queue_interrupt(&svm->vcpu, vector, false);
                 break;
         default:
                 break;
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8981654ad061..29b49f09a019 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -801,8 +801,9 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu, unsigned nr,
                 return;
         }
 
-        if (nr == BP_VECTOR || nr == OF_VECTOR) {
-                vmcs_write32(VM_ENTRY_INSTRUCTION_LEN, 1);
+        if (kvm_exception_is_soft(nr)) {
+                vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
+                             vmx->vcpu.arch.event_exit_inst_len);
                 intr_info |= INTR_TYPE_SOFT_EXCEPTION;
         } else
                 intr_info |= INTR_TYPE_HARD_EXCEPTION;
@@ -2445,9 +2446,11 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu)
         vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
 }
 
-static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
+static void vmx_inject_irq(struct kvm_vcpu *vcpu)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
+        uint32_t intr;
+        int irq = vcpu->arch.interrupt.nr;
 
         KVMTRACE_1D(INJ_VIRQ, vcpu, (u32)irq, handler);
 
@@ -2462,8 +2465,14 @@ static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
                 kvm_rip_write(vcpu, vmx->rmode.irq.rip - 1);
                 return;
         }
-        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD,
-                        irq | INTR_TYPE_EXT_INTR | INTR_INFO_VALID_MASK);
+        intr = irq | INTR_INFO_VALID_MASK;
+        if (vcpu->arch.interrupt.soft) {
+                intr |= INTR_TYPE_SOFT_INTR;
+                vmcs_write32(VM_ENTRY_INSTRUCTION_LEN,
+                             vmx->vcpu.arch.event_exit_inst_len);
+        } else
+                intr |= INTR_TYPE_EXT_INTR;
+        vmcs_write32(VM_ENTRY_INTR_INFO_FIELD, intr);
 }
 
 static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
@@ -3024,6 +3033,7 @@ static int handle_task_switch(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                                               GUEST_INTR_STATE_NMI);
                         break;
                 case INTR_TYPE_EXT_INTR:
+                case INTR_TYPE_SOFT_INTR:
                         kvm_clear_interrupt_queue(vcpu);
                         break;
                 case INTR_TYPE_HARD_EXCEPTION:
@@ -3295,16 +3305,24 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
                 vmcs_clear_bits(GUEST_INTERRUPTIBILITY_INFO,
                                 GUEST_INTR_STATE_NMI);
                 break;
-        case INTR_TYPE_HARD_EXCEPTION:
         case INTR_TYPE_SOFT_EXCEPTION:
+                vmx->vcpu.arch.event_exit_inst_len =
+                        vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+                /* fall through */
+        case INTR_TYPE_HARD_EXCEPTION:
                 if (idt_vectoring_info & VECTORING_INFO_DELIVER_CODE_MASK) {
                         u32 err = vmcs_read32(IDT_VECTORING_ERROR_CODE);
                         kvm_queue_exception_e(&vmx->vcpu, vector, err);
                 } else
                         kvm_queue_exception(&vmx->vcpu, vector);
                 break;
+        case INTR_TYPE_SOFT_INTR:
+                vmx->vcpu.arch.event_exit_inst_len =
+                        vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+                /* fall through */
         case INTR_TYPE_EXT_INTR:
-                kvm_queue_interrupt(&vmx->vcpu, vector);
+                kvm_queue_interrupt(&vmx->vcpu, vector,
+                        type == INTR_TYPE_SOFT_INTR);
                 break;
         default:
                 break;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 54eec3565485..73cfe87fba10 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1441,7 +1441,7 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
                 return -ENXIO;
         vcpu_load(vcpu);
 
-        kvm_queue_interrupt(vcpu, irq->irq);
+        kvm_queue_interrupt(vcpu, irq->irq, false);
 
         vcpu_put(vcpu);
 
@@ -3161,7 +3161,7 @@ static void inject_irq(struct kvm_vcpu *vcpu)
         }
 
         if (vcpu->arch.interrupt.pending) {
-                kvm_x86_ops->set_irq(vcpu, vcpu->arch.interrupt.nr);
+                kvm_x86_ops->set_irq(vcpu);
                 return;
         }
 
@@ -3174,8 +3174,9 @@ static void inject_irq(struct kvm_vcpu *vcpu)
                 }
         } else if (kvm_cpu_has_interrupt(vcpu)) {
                 if (kvm_x86_ops->interrupt_allowed(vcpu)) {
-                        kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu));
-                        kvm_x86_ops->set_irq(vcpu, vcpu->arch.interrupt.nr);
+                        kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu),
+                                            false);
+                        kvm_x86_ops->set_irq(vcpu);
                 }
         }
 }
@@ -4098,7 +4099,7 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
         pending_vec = find_first_bit(
                 (const unsigned long *)sregs->interrupt_bitmap, max_bits);
         if (pending_vec < max_bits) {
-                kvm_queue_interrupt(vcpu, pending_vec);
+                kvm_queue_interrupt(vcpu, pending_vec, false);
                 pr_debug("Set back pending irq %d\n", pending_vec);
                 if (irqchip_in_kernel(vcpu->kvm))
                         kvm_pic_clear_isr_ack(vcpu->kvm);
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index c1f1a8ceba64..4c8e10af78e8 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -8,9 +8,11 @@ static inline void kvm_clear_exception_queue(struct kvm_vcpu *vcpu)
         vcpu->arch.exception.pending = false;
 }
 
-static inline void kvm_queue_interrupt(struct kvm_vcpu *vcpu, u8 vector)
+static inline void kvm_queue_interrupt(struct kvm_vcpu *vcpu, u8 vector,
+        bool soft)
 {
         vcpu->arch.interrupt.pending = true;
+        vcpu->arch.interrupt.soft = soft;
         vcpu->arch.interrupt.nr = vector;
 }
 
@@ -24,4 +26,9 @@ static inline bool kvm_event_needs_reinjection(struct kvm_vcpu *vcpu)
         return vcpu->arch.exception.pending || vcpu->arch.interrupt.pending ||
                 vcpu->arch.nmi_injected;
 }
+
+static inline bool kvm_exception_is_soft(unsigned int nr)
+{
+        return (nr == BP_VECTOR) || (nr == OF_VECTOR);
+}
 #endif