KVM: x86: Unexport x86_emulate_instruction()

Allowing x86_emulate_instruction() to be called directly has led to
subtle bugs being introduced, e.g. not setting EMULTYPE_NO_REEXECUTE
in the emulation type.  While most of the blame lies on re-execute
being opt-out, exporting x86_emulate_instruction() also exposes its
cr2 parameter, which may have contributed to commit d391f120
("x86/kvm/vmx: do not use vm-exit instruction length for fast MMIO
when running nested") using x86_emulate_instruction() instead of
emulate_instruction() because "hey, I have a cr2!", which in turn
introduced its EMULTYPE_NO_REEXECUTE bug.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -1240,20 +1240,9 @@ enum emulation_result {
 #define EMULTYPE_ALLOW_RETRY	    (1 << 3)
 #define EMULTYPE_NO_UD_ON_FAIL	    (1 << 4)
 #define EMULTYPE_VMWARE		    (1 << 5)
-int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
-			    int emulation_type, void *insn, int insn_len);
-
-static inline int kvm_emulate_instruction(struct kvm_vcpu *vcpu,
-			int emulation_type)
-{
-	return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);
-}
-
-static inline int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
-						      void *insn, int insn_len)
-{
-	return x86_emulate_instruction(vcpu, 0, 0, insn, insn_len);
-}
+int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
+int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
+					void *insn, int insn_len);
 
 void kvm_enable_efer_bits(u64);
 bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer);

arch/x86/kvm/x86.c

@@ -6282,7 +6282,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
 
 	return r;
 }
-EXPORT_SYMBOL_GPL(x86_emulate_instruction);
+
+int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type)
+{
+	return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);
+}
+EXPORT_SYMBOL_GPL(kvm_emulate_instruction);
+
+int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
+					void *insn, int insn_len)
+{
+	return x86_emulate_instruction(vcpu, 0, 0, insn, insn_len);
+}
+EXPORT_SYMBOL_GPL(kvm_emulate_instruction_from_buffer);
 
 static int kvm_fast_pio_out(struct kvm_vcpu *vcpu, int size,
 			    unsigned short port)

arch/x86/kvm/x86.h

@@ -274,6 +274,8 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
 bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
 					  int page_num);
 bool kvm_vector_hashing_enabled(void);
+int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
+			    int emulation_type, void *insn, int insn_len);
 
 #define KVM_SUPPORTED_XCR0     (XFEATURE_MASK_FP | XFEATURE_MASK_SSE \
 				| XFEATURE_MASK_YMM | XFEATURE_MASK_BNDREGS \