implements and fixes CLIC CSR behavior

src/iss/arch/riscv_hart_common.h

@@ -221,6 +221,7 @@ struct vm_info {
 
 struct feature_config {
     uint64_t clic_base{0xc0000000};
+    unsigned clic_int_ctl_bits{4};
     unsigned clic_num_irq{16};
     unsigned clic_num_trigger{0};
     uint64_t tcm_base{0x10000000};

src/iss/arch/riscv_hart_m_p.h

@@ -289,6 +289,8 @@ protected:
         uint32_t raw;
     };
     std::vector<clic_int_reg_t> clic_int_reg;
+    uint8_t clic_mprev_lvl{0};
+    uint8_t clic_mact_lvl{0};
 
     std::vector<uint8_t> tcm;
 
@@ -430,6 +432,8 @@ riscv_hart_m_p<BASE, FEAT>::riscv_hart_m_p(feature_config cfg)
         clic_int_reg.resize(cfg.clic_num_irq,  clic_int_reg_t{.raw=0});
         clic_cfg_reg=0x20;
         clic_info_reg = (/*CLICINTCTLBITS*/ 4U<<21) + cfg.clic_num_irq;
+        clic_mact_lvl = clic_mprev_lvl = (1<<(cfg.clic_int_ctl_bits)) - 1;
+        csr[mintthresh] = (1<<(cfg.clic_int_ctl_bits)) - 1;
         insert_mem_range(cfg.clic_base, 0x5000UL,
                 [this](phys_addr_t addr, unsigned length, uint8_t * const data) { return read_clic(addr.val, length, data);},
                 [this](phys_addr_t addr, unsigned length, uint8_t const * const data) {return write_clic(addr.val, length, data);});
@@ -869,18 +873,26 @@ template <typename BASE, features_e FEAT> iss::status riscv_hart_m_p<BASE, FEAT>
 template <typename BASE, features_e FEAT> iss::status riscv_hart_m_p<BASE, FEAT>::read_cause(unsigned addr, reg_t &val) {
     auto res = csr[addr];
     if((FEAT & features_e::FEAT_CLIC) && (csr[mtvec]&0x3)==3) {
-        res |= state.mstatus.MPIE<<27;
-        res |= state.mstatus.MPP<<28;
-    }
-    val=res;
+        val = csr[addr] & ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1) | (0xfUL<<16));
+        val |= clic_mprev_lvl<<16;
+        val |= state.mstatus.MPIE<<27;
+        val |= state.mstatus.MPP<<28;
+    } else
+        val = csr[addr] & ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1));
     return iss::Ok;
 }
 
 template <typename BASE, features_e FEAT> iss::status riscv_hart_m_p<BASE, FEAT>::write_cause(unsigned addr, reg_t val) {
     csr[addr] = val & ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1));
     if((FEAT & features_e::FEAT_CLIC) && (csr[mtvec]&0x3)==3) {
+        auto mask = ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1) | (0xfUL<<16));
+        csr[addr] = (val & mask) | (csr[addr] & ~mask);
+        clic_mprev_lvl = ((val>>16)&0xff) | (1<<(8-cfg. clic_int_ctl_bits)) - 1;
         state.mstatus.MPIE=(val>>27)&0x1;
         state.mstatus.MPP=(val>>28)&0x3;
+    } else {
+        auto mask = ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1));
+        csr[addr] = (val & mask) | (csr[addr] & ~mask);
     }
     return iss::Ok;
 }
@@ -955,7 +967,7 @@ template <typename BASE, features_e FEAT> iss::status riscv_hart_m_p<BASE, FEAT>
 
 template<typename BASE, features_e FEAT>
 iss::status riscv_hart_m_p<BASE, FEAT>::write_intthresh(unsigned addr, reg_t val) {
-    csr[addr]= val &0xff;
+    csr[addr]= (val &0xff) | (1<<(cfg.clic_int_ctl_bits)) - 1;
     return iss::Ok;
 }
 
@@ -1107,6 +1119,7 @@ template <typename BASE, features_e FEAT> inline void riscv_hart_m_p<BASE, FEAT>
 }
 
 template <typename BASE, features_e FEAT> void riscv_hart_m_p<BASE, FEAT>::check_interrupt() {
+    //TODO: Implement CLIC functionality
     //auto ideleg = csr[mideleg];
     // Multiple simultaneous interrupts and traps at the same privilege level are
     // handled in the following decreasing priority order:

src/iss/arch/riscv_hart_mu_p.h

@@ -304,6 +304,8 @@ protected:
         uint32_t raw;
     };
     std::vector<clic_int_reg_t> clic_int_reg;
+    uint8_t clic_mprev_lvl{0}, clic_uprev_lvl{0};
+    uint8_t clic_mact_lvl{0}, clic_uact_lvl{0};
 
     std::vector<uint8_t> tcm;
 
@@ -486,6 +488,10 @@ riscv_hart_mu_p<BASE, FEAT>::riscv_hart_mu_p(feature_config cfg)
         clic_int_reg.resize(cfg.clic_num_irq,  clic_int_reg_t{.raw=0});
         clic_cfg_reg=0x30;
         clic_info_reg = (/*CLICINTCTLBITS*/ 4U<<21) + cfg.clic_num_irq;
+        clic_mact_lvl = clic_mprev_lvl = (1<<(cfg.clic_int_ctl_bits)) - 1;
+        clic_uact_lvl = clic_uprev_lvl = (1<<(cfg.clic_int_ctl_bits)) - 1;
+        csr[mintthresh] = (1<<(cfg.clic_int_ctl_bits)) - 1;
+        csr[uintthresh] = (1<<(cfg.clic_int_ctl_bits)) - 1;
         insert_mem_range(cfg.clic_base, 0x5000UL,
                 [this](phys_addr_t addr, unsigned length, uint8_t * const data) { return read_clic(addr.val, length, data);},
                 [this](phys_addr_t addr, unsigned length, uint8_t const * const data) {return write_clic(addr.val, length, data);});
@@ -1026,36 +1032,44 @@ template <typename BASE, features_e FEAT> iss::status riscv_hart_mu_p<BASE, FEAT
 }
 
 template <typename BASE, features_e FEAT> iss::status riscv_hart_mu_p<BASE, FEAT>::read_cause(unsigned addr, reg_t &val) {
-    auto res = csr[addr];
     if((FEAT & features_e::FEAT_CLIC) && (csr[mtvec]&0x3)==3) {
+        val = csr[addr] & ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1) | (0xfUL<<16));
         auto mode = (addr >> 8) & 0x3;
         switch(mode) {
         case 0:
-            res |= state.mstatus.UPIE<<27;
+            val |= clic_uprev_lvl<<16;
+            val |= state.mstatus.UPIE<<27;
             break;
         default:
-            res |= state.mstatus.MPIE<<27;
-            res |= state.mstatus.MPP<<28;
+            val |= clic_mprev_lvl<<16;
+            val |= state.mstatus.MPIE<<27;
+            val |= state.mstatus.MPP<<28;
             break;
         }
-    }
-    val=res;
+    } else
+        val = csr[addr] & ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1));
     return iss::Ok;
 }
 
 template <typename BASE, features_e FEAT> iss::status riscv_hart_mu_p<BASE, FEAT>::write_cause(unsigned addr, reg_t val) {
-    csr[addr] = val & ((1UL<<(traits<BASE>::XLEN-1))|(mcause_max_irq-1));
     if((FEAT & features_e::FEAT_CLIC) && (csr[mtvec]&0x3)==3) {
+        auto mask = ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1) | (0xfUL<<16));
+        csr[addr] = (val & mask) | (csr[addr] & ~mask);
         auto mode = (addr >> 8) & 0x3;
         switch(mode) {
         case 0:
+            clic_uprev_lvl = ((val>>16)&0xff) | (1<<(8-cfg. clic_int_ctl_bits)) - 1;
             state.mstatus.UPIE=(val>>27)&0x1;
             break;
         default:
+            clic_mprev_lvl = ((val>>16)&0xff) | (1<<(8-cfg. clic_int_ctl_bits)) - 1;
             state.mstatus.MPIE=(val>>27)&0x1;
             state.mstatus.MPP=(val>>28)&0x3;
             break;
         }
+    } else {
+        auto mask = ((1UL<<(traits<BASE>::XLEN-1)) | (mcause_max_irq-1));
+        csr[addr] = (val & mask) | (csr[addr] & ~mask);
     }
     return iss::Ok;
 }
@@ -1146,7 +1160,7 @@ template <typename BASE, features_e FEAT> iss::status riscv_hart_mu_p<BASE, FEAT
 
 template<typename BASE, features_e FEAT>
 iss::status riscv_hart_mu_p<BASE, FEAT>::write_intthresh(unsigned addr, reg_t val) {
-    csr[addr]= val &0xff;
+    csr[addr]= (val &0xff) | (1<<(cfg.clic_int_ctl_bits)) - 1;
     return iss::Ok;
 }
 
@@ -1298,6 +1312,7 @@ template <typename BASE, features_e FEAT> inline void riscv_hart_mu_p<BASE, FEAT
 }
 
 template <typename BASE, features_e FEAT> void riscv_hart_mu_p<BASE, FEAT>::check_interrupt() {
+    //TODO: Implement CLIC functionality
     auto ideleg = csr[mideleg];
     // Multiple simultaneous interrupts and traps at the same privilege level are
     // handled in the following decreasing priority order: