KVM: prevent spurious exit to userspace during task switch emulation.

[safe/jmp/linux-2.6] / arch / x86 / kvm / svm.c

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 87b36fb..ab78eb8 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2222,6 +2222,8 @@ static int task_switch_interception(struct vcpu_svm *svm)
                svm->vmcb->control.exit_int_info & SVM_EXITINTINFO_TYPE_MASK;
        uint32_t idt_v =
                svm->vmcb->control.exit_int_info & SVM_EXITINTINFO_VALID;
+       bool has_error_code = false;
+       u32 error_code = 0;
 
        tss_selector = (u16)svm->vmcb->control.exit_info_1;
 
@@ -2242,6 +2244,12 @@ static int task_switch_interception(struct vcpu_svm *svm)
                        svm->vcpu.arch.nmi_injected = false;
                        break;
                case SVM_EXITINTINFO_TYPE_EXEPT:
+                       if (svm->vmcb->control.exit_info_2 &
+                           (1ULL << SVM_EXITINFOSHIFT_TS_HAS_ERROR_CODE)) {
+                               has_error_code = true;
+                               error_code =
+                                       (u32)svm->vmcb->control.exit_info_2;
+                       }
                        kvm_clear_exception_queue(&svm->vcpu);
                        break;
                case SVM_EXITINTINFO_TYPE_INTR:
@@ -2258,7 +2266,14 @@ static int task_switch_interception(struct vcpu_svm *svm)
             (int_vec == OF_VECTOR || int_vec == BP_VECTOR)))
                skip_emulated_instruction(&svm->vcpu);
 
-       return kvm_task_switch(&svm->vcpu, tss_selector, reason);
+       if (kvm_task_switch(&svm->vcpu, tss_selector, reason,
+                               has_error_code, error_code) == EMULATE_FAIL) {
+               svm->vcpu.run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+               svm->vcpu.run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+               svm->vcpu.run->internal.ndata = 0;
+               return 0;
+       }
+       return 1;
 }
 
 static int cpuid_interception(struct vcpu_svm *svm)