[PATCH v3 5/6] target/loongarch: Support LoongArch32 DMW

[Jiajie Chen <c@jia.je>]

LA32 uses a different encoding for CSR.DMW and a new direct mapping
mechanism.

Signed-off-by: Jiajie Chen <c@jia.je>
---
 target/loongarch/cpu-csr.h    |  7 +++----
 target/loongarch/tlb_helper.c | 31 ++++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/target/loongarch/cpu-csr.h b/target/loongarch/cpu-csr.h
index 48ed2e0632..b93f99a9ef 100644
--- a/target/loongarch/cpu-csr.h
+++ b/target/loongarch/cpu-csr.h
@@ -188,10 +188,9 @@ FIELD(CSR_DMW, PLV1, 1, 1)
 FIELD(CSR_DMW, PLV2, 2, 1)
 FIELD(CSR_DMW, PLV3, 3, 1)
 FIELD(CSR_DMW, MAT, 4, 2)
-FIELD(CSR_DMW, VSEG, 60, 4)
-
-#define dmw_va2pa(va) \
-    (va & MAKE_64BIT_MASK(0, TARGET_VIRT_ADDR_SPACE_BITS))
+FIELD(CSR_DMW_32, PSEG, 25, 3)
+FIELD(CSR_DMW_32, VSEG, 29, 3)
+FIELD(CSR_DMW_64, VSEG, 60, 4)
 
 /* Debug CSRs */
 #define LOONGARCH_CSR_DBG            0x500 /* debug config */
diff --git a/target/loongarch/tlb_helper.c b/target/loongarch/tlb_helper.c
index 690c6ef25f..cf6f5863f9 100644
--- a/target/loongarch/tlb_helper.c
+++ b/target/loongarch/tlb_helper.c
@@ -173,6 +173,18 @@ static int loongarch_map_address(CPULoongArchState *env, hwaddr *physical,
     return TLBRET_NOMATCH;
 }
 
+static hwaddr dmw_va2pa(CPULoongArchState *env, target_ulong va,
+                        target_ulong dmw)
+{
+    if (env->mode == LA64) {
+        return va & TARGET_PHYS_MASK;
+    } else {
+        uint32_t pseg = FIELD_EX32(dmw, CSR_DMW_32, PSEG);
+        return (va & MAKE_64BIT_MASK(0, R_CSR_DMW_32_VSEG_SHIFT)) | \
+            (pseg << R_CSR_DMW_32_VSEG_SHIFT);
+    }
+}
+
 static int get_physical_address(CPULoongArchState *env, hwaddr *physical,
                                 int *prot, target_ulong address,
                                 MMUAccessType access_type, int mmu_idx)
@@ -184,6 +196,11 @@ static int get_physical_address(CPULoongArchState *env, hwaddr *physical,
     uint8_t da = FIELD_EX64(env->CSR_CRMD, CSR_CRMD, DA);
     uint8_t pg = FIELD_EX64(env->CSR_CRMD, CSR_CRMD, PG);
 
+    /* Truncate high 32 bits for LA32 */
+    if (env->mode == LA32) {
+        address = (uint32_t)address;
+    }
+
     /* Check PG and DA */
     if (da & !pg) {
         *physical = address & TARGET_PHYS_MASK;
@@ -192,12 +209,20 @@ static int get_physical_address(CPULoongArchState *env, hwaddr *physical,
     }
 
     plv = kernel_mode | (user_mode << R_CSR_DMW_PLV3_SHIFT);
-    base_v = address >> R_CSR_DMW_VSEG_SHIFT;
+    if (env->mode == LA64) {
+        base_v = address >> R_CSR_DMW_64_VSEG_SHIFT;
+    } else {
+        base_v = address >> R_CSR_DMW_32_VSEG_SHIFT;
+    }
     /* Check direct map window */
     for (int i = 0; i < 4; i++) {
-        base_c = FIELD_EX64(env->CSR_DMW[i], CSR_DMW, VSEG);
+        if (env->mode == LA64) {
+            base_c = FIELD_EX64(env->CSR_DMW[i], CSR_DMW_64, VSEG);
+        } else {
+            base_c = FIELD_EX64(env->CSR_DMW[i], CSR_DMW_32, VSEG);
+        }
         if ((plv & env->CSR_DMW[i]) && (base_c == base_v)) {
-            *physical = dmw_va2pa(address);
+            *physical = dmw_va2pa(env, address, env->CSR_DMW[i]);
             *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
             return TLBRET_MATCH;
         }
-- 
2.39.2