diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index 358707f60d99..0ffaa3156a4e 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -373,6 +373,7 @@ enum vmcs_field {
 #define GUEST_INTR_STATE_MOV_SS		0x00000002
 #define GUEST_INTR_STATE_SMI		0x00000004
 #define GUEST_INTR_STATE_NMI		0x00000008
+#define GUEST_INTR_STATE_ENCLAVE_INTR	0x00000010
 
 /* GUEST_ACTIVITY_STATE flags */
 #define GUEST_ACTIVITY_ACTIVE		0
diff --git a/arch/x86/include/uapi/asm/vmx.h b/arch/x86/include/uapi/asm/vmx.h
index b8e650a985e3..946d761adbd3 100644
--- a/arch/x86/include/uapi/asm/vmx.h
+++ b/arch/x86/include/uapi/asm/vmx.h
@@ -27,6 +27,7 @@
 
 
 #define VMX_EXIT_REASONS_FAILED_VMENTRY         0x80000000
+#define VMX_EXIT_REASONS_SGX_ENCLAVE_MODE	0x08000000
 
 #define EXIT_REASON_EXCEPTION_NMI       0
 #define EXIT_REASON_EXTERNAL_INTERRUPT  1
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index e02ebc28270e..baaea9bbb8e5 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4111,6 +4111,8 @@ static void prepare_vmcs12(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12,
 {
 	/* update exit information fields: */
 	vmcs12->vm_exit_reason = vm_exit_reason;
+	if (to_vmx(vcpu)->exit_reason.enclave_mode)
+		vmcs12->vm_exit_reason |= VMX_EXIT_REASONS_SGX_ENCLAVE_MODE;
 	vmcs12->exit_qualification = exit_qualification;
 	vmcs12->vm_exit_intr_info = exit_intr_info;
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c05e6e2854b5..09f2c9ec4468 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1588,12 +1588,25 @@ static int vmx_rtit_ctl_check(struct kvm_vcpu *vcpu, u64 data)
 
 static bool vmx_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int insn_len)
 {
+	/*
+	 * Emulation of instructions in SGX enclaves is impossible as RIP does
+	 * not point  tthe failing instruction, and even if it did, the code
+	 * stream is inaccessible.  Inject #UD instead of exiting to userspace
+	 * so that guest userspace can't DoS the guest simply by triggering
+	 * emulation (enclaves are CPL3 only).
+	 */
+	if (to_vmx(vcpu)->exit_reason.enclave_mode) {
+		kvm_queue_exception(vcpu, UD_VECTOR);
+		return false;
+	}
 	return true;
 }
 
 static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
 {
+	union vmx_exit_reason exit_reason = to_vmx(vcpu)->exit_reason;
 	unsigned long rip, orig_rip;
+	u32 instr_len;
 
 	/*
 	 * Using VMCS.VM_EXIT_INSTRUCTION_LEN on EPT misconfig depends on
@@ -1604,9 +1617,33 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
 	 * i.e. we end up advancing IP with some random value.
 	 */
 	if (!static_cpu_has(X86_FEATURE_HYPERVISOR) ||
-	    to_vmx(vcpu)->exit_reason.basic != EXIT_REASON_EPT_MISCONFIG) {
+	    exit_reason.basic != EXIT_REASON_EPT_MISCONFIG) {
+		instr_len = vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+
+		/*
+		 * Emulating an enclave's instructions isn't supported as KVM
+		 * cannot access the enclave's memory or its true RIP, e.g. the
+		 * vmcs.GUEST_RIP points at the exit point of the enclave, not
+		 * the RIP that actually triggered the VM-Exit.  But, because
+		 * most instructions that cause VM-Exit will #UD in an enclave,
+		 * most instruction-based VM-Exits simply do not occur.
+		 *
+		 * There are a few exceptions, notably the debug instructions
+		 * INT1ICEBRK and INT3, as they are allowed in debug enclaves
+		 * and generate #DB/#BP as expected, which KVM might intercept.
+		 * But again, the CPU does the dirty work and saves an instr
+		 * length of zero so VMMs don't shoot themselves in the foot.
+		 * WARN if KVM tries to skip a non-zero length instruction on
+		 * a VM-Exit from an enclave.
+		 */
+		if (!instr_len)
+			goto rip_updated;
+
+		WARN(exit_reason.enclave_mode,
+		     "KVM: skipping instruction after SGX enclave VM-Exit");
+
 		orig_rip = kvm_rip_read(vcpu);
-		rip = orig_rip + vmcs_read32(VM_EXIT_INSTRUCTION_LEN);
+		rip = orig_rip + instr_len;
 #ifdef CONFIG_X86_64
 		/*
 		 * We need to mask out the high 32 bits of RIP if not in 64-bit
@@ -1622,6 +1659,7 @@ static int skip_emulated_instruction(struct kvm_vcpu *vcpu)
 			return 0;
 	}
 
+rip_updated:
 	/* skipping an emulated instruction also counts */
 	vmx_set_interrupt_shadow(vcpu, 0);
 
@@ -5353,6 +5391,9 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 {
 	gpa_t gpa;
 
+	if (!vmx_can_emulate_instruction(vcpu, NULL, 0))
+		return 1;
+
 	/*
 	 * A nested guest cannot optimize MMIO vmexits, because we have an
 	 * nGPA here instead of the required GPA.
