diff --git a/tcg/aarch64/tcg-target.h b/tcg/aarch64/tcg-target.h
index 8d244292aa..c0b0f614ba 100644
--- a/tcg/aarch64/tcg-target.h
+++ b/tcg/aarch64/tcg-target.h
@@ -54,6 +54,8 @@ typedef enum {
 #define TCG_TARGET_CALL_STACK_OFFSET    0
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_NORMAL
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_EVEN
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_NORMAL
 
 /* optional instructions */
 #define TCG_TARGET_HAS_div_i32          1
diff --git a/tcg/arm/tcg-target.h b/tcg/arm/tcg-target.h
index 91b8954804..def2a189e6 100644
--- a/tcg/arm/tcg-target.h
+++ b/tcg/arm/tcg-target.h
@@ -91,6 +91,8 @@ extern bool use_neon_instructions;
 #define TCG_TARGET_CALL_STACK_OFFSET	0
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_NORMAL
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_EVEN
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_EVEN
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_BY_REF
 
 /* optional instructions */
 #define TCG_TARGET_HAS_ext8s_i32        1
diff --git a/tcg/loongarch64/tcg-target.h b/tcg/loongarch64/tcg-target.h
index 8b151e7f6f..17b8193aa5 100644
--- a/tcg/loongarch64/tcg-target.h
+++ b/tcg/loongarch64/tcg-target.h
@@ -92,6 +92,8 @@ typedef enum {
 #define TCG_TARGET_CALL_STACK_OFFSET    0
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_NORMAL
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_NORMAL
 
 /* optional instructions */
 #define TCG_TARGET_HAS_movcond_i32      1
diff --git a/tcg/mips/tcg-target.h b/tcg/mips/tcg-target.h
index 7bc8e15293..68b11e4d48 100644
--- a/tcg/mips/tcg-target.h
+++ b/tcg/mips/tcg-target.h
@@ -89,6 +89,8 @@ typedef enum {
 # define TCG_TARGET_CALL_ARG_I64      TCG_CALL_ARG_NORMAL
 #endif
 #define TCG_TARGET_CALL_ARG_I32       TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128      TCG_CALL_ARG_EVEN
+#define TCG_TARGET_CALL_RET_I128      TCG_CALL_RET_NORMAL
 
 /* MOVN/MOVZ instructions detection */
 #if (defined(__mips_isa_rev) && (__mips_isa_rev >= 1)) || \
diff --git a/tcg/ppc/tcg-target.c.inc b/tcg/ppc/tcg-target.c.inc
index f3fec14118..afadf9a1e3 100644
--- a/tcg/ppc/tcg-target.c.inc
+++ b/tcg/ppc/tcg-target.c.inc
@@ -54,6 +54,9 @@
 #else
 # define TCG_TARGET_CALL_ARG_I64   TCG_CALL_ARG_NORMAL
 #endif
+/* Note sysv arg alignment applies only to 2-word types, not more. */
+#define TCG_TARGET_CALL_ARG_I128   TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_RET_I128   TCG_CALL_RET_NORMAL
 
 /* For some memory operations, we need a scratch that isn't R0.  For the AIX
    calling convention, we can re-use the TOC register since we'll be reloading
diff --git a/tcg/riscv/tcg-target.h b/tcg/riscv/tcg-target.h
index 1337bc1f1e..0deb33701f 100644
--- a/tcg/riscv/tcg-target.h
+++ b/tcg/riscv/tcg-target.h
@@ -85,9 +85,12 @@ typedef enum {
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_NORMAL
 #if TCG_TARGET_REG_BITS == 32
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_EVEN
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_EVEN
 #else
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_NORMAL
 #endif
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_NORMAL
 
 /* optional instructions */
 #define TCG_TARGET_HAS_movcond_i32      0
diff --git a/tcg/s390x/tcg-target.h b/tcg/s390x/tcg-target.h
index e597e47e60..a05b473117 100644
--- a/tcg/s390x/tcg-target.h
+++ b/tcg/s390x/tcg-target.h
@@ -169,6 +169,8 @@ extern uint64_t s390_facilities[3];
 #define TCG_TARGET_CALL_STACK_OFFSET	160
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_EXTEND
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_BY_REF
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_BY_REF
 
 #define TCG_TARGET_HAS_MEMORY_BSWAP   1
 
diff --git a/tcg/sparc64/tcg-target.h b/tcg/sparc64/tcg-target.h
index 1d6a5c8b07..ffe22b1d21 100644
--- a/tcg/sparc64/tcg-target.h
+++ b/tcg/sparc64/tcg-target.h
@@ -73,6 +73,8 @@ typedef enum {
 #define TCG_TARGET_CALL_STACK_OFFSET    (128 + 6*8 + TCG_TARGET_STACK_BIAS)
 #define TCG_TARGET_CALL_ARG_I32         TCG_CALL_ARG_EXTEND
 #define TCG_TARGET_CALL_ARG_I64         TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_ARG_I128        TCG_CALL_ARG_NORMAL
+#define TCG_TARGET_CALL_RET_I128        TCG_CALL_RET_NORMAL
 
 #if defined(__VIS__) && __VIS__ >= 0x300
 #define use_vis3_instructions  1
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 865ed5ea0f..163913c95f 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -765,8 +765,8 @@ static void init_call_layout(TCGHelperInfo *info)
         break;
     case dh_typecode_i128:
         info->nr_out = 128 / TCG_TARGET_REG_BITS;
-        info->out_kind = TCG_CALL_RET_NORMAL; /* TODO */
-        switch (/* TODO */ TCG_CALL_RET_NORMAL) {
+        info->out_kind = TCG_TARGET_CALL_RET_I128;
+        switch (TCG_TARGET_CALL_RET_I128) {
         case TCG_CALL_RET_NORMAL:
             /* Query the last register now to trigger any assert early. */
             tcg_target_call_oarg_reg(info->out_kind, info->nr_out - 1);
@@ -854,7 +854,7 @@ static void init_call_layout(TCGHelperInfo *info)
             break;
 
         case TCG_TYPE_I128:
-            switch (/* TODO */ TCG_CALL_ARG_NORMAL) {
+            switch (TCG_TARGET_CALL_ARG_I128) {
             case TCG_CALL_ARG_EVEN:
                 layout_arg_even(&cum);
                 /* fall through */