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 78af522..ab78eb8 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2266,8 +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,
-                              has_error_code, error_code);
+       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)