target/loongarch: Update matched ptw bit A/D with PTW supported

With hardware PTE supported, bit A will be set if there is read access
or instruction fetch, and bit D will be set with write access.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Song Gao <gaosong@loongson.cn>

target/loongarch/cpu-mmu.h

@@ -61,6 +61,32 @@ static inline bool pte_write(CPULoongArchState *env, uint64_t entry)
     return !!writable;
 }
 
+/*
+ * The folloing functions should be called with PTW enable checked
+ * With hardware PTW enabled
+ *   Bit D will be set by hardware with write access
+ *   Bit A will be set by hardware with read/intruction fetch access
+ */
+static inline uint64_t pte_mkaccess(uint64_t entry)
+{
+    return FIELD_DP64(entry, TLBENTRY, V, 1);
+}
+
+static inline uint64_t pte_mkdirty(uint64_t entry)
+{
+    return FIELD_DP64(entry, TLBENTRY, D, 1);
+}
+
+static inline bool pte_access(uint64_t entry)
+{
+    return !!FIELD_EX64(entry, TLBENTRY, V);
+}
+
+static inline bool pte_dirty(uint64_t entry)
+{
+    return !!FIELD_EX64(entry, TLBENTRY, D);
+}
+
 bool check_ps(CPULoongArchState *ent, uint8_t ps);
 TLBRet loongarch_check_pte(CPULoongArchState *env, MMUContext *context,
                            MMUAccessType access_type, int mmu_idx);

target/loongarch/cpu_helper.c

@@ -107,15 +107,52 @@ TLBRet loongarch_check_pte(CPULoongArchState *env, MMUContext *context,
     return TLBRET_MATCH;
 }
 
+static MemTxResult loongarch_cmpxchg_phys(CPUState *cs, hwaddr phys,
+                                          uint64_t old, uint64_t new)
+{
+    hwaddr addr1, l = 8;
+    MemoryRegion *mr;
+    uint8_t *ram_ptr;
+    uint64_t old1;
+    MemTxResult ret;
+
+    rcu_read_lock();
+    mr = address_space_translate(cs->as, phys, &addr1, &l,
+                                 false, MEMTXATTRS_UNSPECIFIED);
+    if (!memory_region_is_ram(mr)) {
+        /*
+         * Misconfigured PTE in ROM (AD bits are not preset) or
+         * PTE is in IO space and can't be updated atomically.
+         */
+         rcu_read_unlock();
+         return MEMTX_ACCESS_ERROR;
+    }
+
+    ram_ptr = qemu_map_ram_ptr(mr->ram_block, addr1);
+    old1 = qatomic_cmpxchg((uint64_t *)ram_ptr, cpu_to_le64(old),
+                           cpu_to_le64(new));
+    old1 = le64_to_cpu(old1);
+    if (old1 == old) {
+        ret = MEMTX_OK;
+    } else {
+        ret = MEMTX_DECODE_ERROR;
+    }
+    rcu_read_unlock();
+
+    return ret;
+}
+
 TLBRet loongarch_ptw(CPULoongArchState *env, MMUContext *context,
                      int access_type, int mmu_idx, int debug)
 {
     CPUState *cs = env_cpu(env);
     target_ulong index = 0, phys = 0;
     uint64_t dir_base, dir_width;
-    uint64_t base;
+    uint64_t base, pte;
     int level;
     vaddr address;
+    TLBRet ret;
+    MemTxResult ret1;
 
     address = context->addr;
     if ((address >> 63) & 0x1) {
@@ -149,7 +186,9 @@ TLBRet loongarch_ptw(CPULoongArchState *env, MMUContext *context,
         }
     }
 
+restart:
     /* pte */
+    pte = base;
     if (level > 0) {
         /* Huge Page. base is pte */
         base = FIELD_DP64(base, TLBENTRY, LEVEL, 0);
@@ -171,7 +210,57 @@ TLBRet loongarch_ptw(CPULoongArchState *env, MMUContext *context,
 
     context->ps = dir_base;
     context->pte = base;
-    return loongarch_check_pte(env, context, access_type, mmu_idx);
+    ret = loongarch_check_pte(env, context, access_type, mmu_idx);
+    if (debug) {
+        return ret;
+    }
+
+    /*
+     * Update bit A/D with hardware PTW supported
+     *
+     * Need atomic compchxg operation with pte update, other vCPUs may
+     * update pte at the same time.
+     */
+    if (ret == TLBRET_MATCH && cpu_has_ptw(env)) {
+        if (access_type == MMU_DATA_STORE && pte_dirty(base)) {
+            return ret;
+        }
+
+        if (access_type != MMU_DATA_STORE && pte_access(base)) {
+            return ret;
+        }
+
+        base = pte_mkaccess(pte);
+        if (access_type == MMU_DATA_STORE) {
+            base = pte_mkdirty(base);
+        }
+        ret1 = loongarch_cmpxchg_phys(cs, phys, pte, base);
+        /* PTE updated by other CPU, reload PTE entry */
+        if (ret1 == MEMTX_DECODE_ERROR) {
+            base = ldq_phys(cs->as, phys);
+            goto restart;
+        }
+
+        base = context->pte_buddy[index];
+        base = pte_mkaccess(base);
+        if (access_type == MMU_DATA_STORE) {
+            base = pte_mkdirty(base);
+        }
+        context->pte_buddy[index] = base;
+
+        /* Bit A/D need be updated with both Even/Odd page with huge pte */
+        if (level > 0) {
+            index = 1 - index;
+            base = context->pte_buddy[index];
+            base = pte_mkaccess(base);
+            if (access_type == MMU_DATA_STORE) {
+                base = pte_mkdirty(base);
+            }
+            context->pte_buddy[index] = base;
+        }
+    }
+
+    return ret;
 }
 
 static TLBRet loongarch_map_address(CPULoongArchState *env,