KVM: MMU: Fix and clean up for_each_gfn_* macros

The expression (sp)->gfn should not be expanded using @gfn.
Although no user of these macros passes a string other than gfn now,
this should be fixed before anyone sees strange errors.

Note: ignored the following checkpatch errors:
  ERROR: Macros with complex values should be enclosed in parenthesis
  ERROR: trailing statements should be on next line
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

arch/x86/kvm/mmu.c

@@ -1644,16 +1644,14 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 static void kvm_mmu_commit_zap_page(struct kvm *kvm,
 				    struct list_head *invalid_list);
 
-#define for_each_gfn_sp(kvm, sp, gfn)					\
-  hlist_for_each_entry(sp,						\
-   &(kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)], hash_link)	\
-	if ((sp)->gfn != (gfn)) {} else
-
-#define for_each_gfn_indirect_valid_sp(kvm, sp, gfn)			\
-  hlist_for_each_entry(sp,						\
-   &(kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)], hash_link)	\
-		if ((sp)->gfn != (gfn) || (sp)->role.direct ||		\
-			(sp)->role.invalid) {} else
+#define for_each_gfn_sp(_kvm, _sp, _gfn)				\
+	hlist_for_each_entry(_sp,					\
+	  &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)], hash_link) \
+		if ((_sp)->gfn != (_gfn)) {} else
+
+#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn)			\
+	for_each_gfn_sp(_kvm, _sp, _gfn)				\
+		if ((_sp)->role.direct || (_sp)->role.invalid) {} else
 
 /* @sp->gfn should be write-protected at the call site */
 static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,