KVM: x86: Handle emulation failure directly in kvm_task_switch()

Consolidate the reporting of emulation failure into kvm_task_switch()
so that it can return EMULATE_USER_EXIT.  This helps pave the way for
removing EMULATE_FAIL altogether.

This also fixes a theoretical bug where task switch interception could
suppress an EMULATE_USER_EXIT return.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index fc40052..69e53aa 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3892,17 +3892,10 @@ static int task_switch_interception(struct vcpu_svm *svm)
        if (int_type != SVM_EXITINTINFO_TYPE_SOFT)
                int_vec = -1;
 
-       if (kvm_task_switch(&svm->vcpu, tss_selector, int_vec, reason,
-                               has_error_code, error_code) == EMULATE_FAIL)
-               goto fail;
 
-       return 1;
 
-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 kvm_task_switch(&svm->vcpu, tss_selector, int_vec, reason,
+                              has_error_code, error_code) != EMULATE_USER_EXIT;
 }
 
 static int cpuid_interception(struct vcpu_svm *svm)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d437159..498270c 100644 (file)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5074,21 +5074,13 @@ static int handle_task_switch(struct kvm_vcpu *vcpu)
                       type != INTR_TYPE_NMI_INTR))
                skip_emulated_instruction(vcpu);
 
-       if (kvm_task_switch(vcpu, tss_selector,
-                           type == INTR_TYPE_SOFT_INTR ? idt_index : -1, reason,
-                           has_error_code, error_code) == EMULATE_FAIL) {
-               vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-               vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
-               vcpu->run->internal.ndata = 0;
-               return 0;
-       }
-
        /*
         * TODO: What about debug traps on tss switch?
         *       Are we supposed to inject them and update dr6?
         */
-
-       return 1;
+       return kvm_task_switch(vcpu, tss_selector,
+                              type == INTR_TYPE_SOFT_INTR ? idt_index : -1,
+                              reason, has_error_code, error_code) != EMULATE_USER_EXIT;
 }
 
 static int handle_ept_violation(struct kvm_vcpu *vcpu)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 802dfb9..bdee7e3 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8693,9 +8693,12 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index,
 
        ret = emulator_task_switch(ctxt, tss_selector, idt_index, reason,
                                   has_error_code, error_code);
-
-       if (ret)
-               return EMULATE_FAIL;
+       if (ret) {
+               vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+               vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+               vcpu->run->internal.ndata = 0;
+               return EMULATE_USER_EXIT;
+       }
 
        kvm_rip_write(vcpu, ctxt->eip);
        kvm_set_rflags(vcpu, ctxt->eflags);