target/mips: Implement Loongson CSR instructions

Loongson introduced CSR instructions since 3A4000, which looks
similar to IOCSR and CPUCFG instructions we seen in LoongArch.

Unfortunately we don't have much document about those instructions,
bit fields of CPUCFG instructions and IOCSR registers can be found
at 3A4000's user manual, while instruction encodings can be found
at arch/mips/include/asm/mach-loongson64/loongson_regs.h from
Linux Kernel.

Our predefined CPUCFG bits are differ from actual 3A4000, since
we can't emulate all CPUCFG features present in 3A4000 for now,
we just enable bits for what we have in TCG.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Message-Id: <20230521214832.20145-2-jiaxun.yang@flygoat.com>
[JY:  Fixed typo in ase_lcsr_available(),
      retrict GEN_FALSE_TRANS]
[PMD: Fix meson's mips_softmmu_ss -> mips_system_ss,
      restrict AddressSpace/MemoryRegion to SysEmu]
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>

target/mips/cpu-defs.c.inc

@@ -895,6 +895,15 @@ const mips_def_t mips_defs[] =
         .CP1_fcr31 = 0,
         .CP1_fcr31_rw_bitmask = 0xFF83FFFF,
         .MSAIR = (0x01 << MSAIR_ProcID) | (0x40 << MSAIR_Rev),
+        .lcsr_cpucfg1 = (1 << CPUCFG1_FP) | (2 << CPUCFG1_FPREV) |
+                    (1 << CPUCFG1_MSA1) | (1 << CPUCFG1_LSLDR0) |
+                    (1 << CPUCFG1_LSPERF) | (1 << CPUCFG1_LSPERFX) |
+                    (1 << CPUCFG1_LSSYNCI) | (1 << CPUCFG1_LLEXC) |
+                    (1 << CPUCFG1_SCRAND) | (1 << CPUCFG1_MUALP) |
+                    (1 << CPUCFG1_KMUALEN) | (1 << CPUCFG1_ITLBT) |
+                    (1 << CPUCFG1_SFBP) | (1 << CPUCFG1_CDMAP),
+        .lcsr_cpucfg2 = (1 << CPUCFG2_LEXT1) | (1 << CPUCFG2_LCSRP) |
+                    (1 << CPUCFG2_LDISBLIKELY),
         .SEGBITS = 48,
         .PABITS = 48,
         .insn_flags = CPU_MIPS64R2 | INSN_LOONGSON3A |

target/mips/cpu.c

@@ -244,6 +244,8 @@ static void mips_cpu_reset_hold(Object *obj)
     env->CP0_PageGrain_rw_bitmask = env->cpu_model->CP0_PageGrain_rw_bitmask;
     env->CP0_PageGrain = env->cpu_model->CP0_PageGrain;
     env->CP0_EBaseWG_rw_bitmask = env->cpu_model->CP0_EBaseWG_rw_bitmask;
+    env->lcsr_cpucfg1 = env->cpu_model->lcsr_cpucfg1;
+    env->lcsr_cpucfg2 = env->cpu_model->lcsr_cpucfg2;
     env->active_fpu.fcr0 = env->cpu_model->CP1_fcr0;
     env->active_fpu.fcr31_rw_bitmask = env->cpu_model->CP1_fcr31_rw_bitmask;
     env->active_fpu.fcr31 = env->cpu_model->CP1_fcr31;
@@ -507,6 +509,14 @@ static void mips_cpu_initfn(Object *obj)
     cpu->count_div = clock_new(OBJECT(obj), "clk-div-count");
     env->count_clock = clock_new(OBJECT(obj), "clk-count");
     env->cpu_model = mcc->cpu_def;
+#ifndef CONFIG_USER_ONLY
+    if (mcc->cpu_def->lcsr_cpucfg2 & (1 << CPUCFG2_LCSRP)) {
+        memory_region_init_io(&env->iocsr.mr, OBJECT(cpu), NULL,
+                                env, "iocsr", UINT64_MAX);
+        address_space_init(&env->iocsr.as,
+                            &env->iocsr.mr, "IOCSR");
+    }
+#endif
 }
 
 static char *mips_cpu_type_name(const char *cpu_model)

target/mips/cpu.h

@@ -3,6 +3,9 @@
 
 #include "cpu-qom.h"
 #include "exec/cpu-defs.h"
+#ifndef CONFIG_USER_ONLY
+#include "exec/memory.h"
+#endif
 #include "fpu/softfloat-types.h"
 #include "hw/clock.h"
 #include "mips-defs.h"
@@ -1068,6 +1071,33 @@ typedef struct CPUArchState {
  */
     int32_t CP0_DESAVE;
     target_ulong CP0_KScratch[MIPS_KSCRATCH_NUM];
+/*
+ * Loongson CSR CPUCFG registers
+ */
+    uint32_t lcsr_cpucfg1;
+#define CPUCFG1_FP     0
+#define CPUCFG1_FPREV  1
+#define CPUCFG1_MMI    4
+#define CPUCFG1_MSA1   5
+#define CPUCFG1_MSA2   6
+#define CPUCFG1_LSLDR0 16
+#define CPUCFG1_LSPERF 17
+#define CPUCFG1_LSPERFX 18
+#define CPUCFG1_LSSYNCI 19
+#define CPUCFG1_LLEXC   20
+#define CPUCFG1_SCRAND  21
+#define CPUCFG1_MUALP   25
+#define CPUCFG1_KMUALEN 26
+#define CPUCFG1_ITLBT   27
+#define CPUCFG1_SFBP    29
+#define CPUCFG1_CDMAP   30
+    uint32_t lcsr_cpucfg2;
+#define CPUCFG2_LEXT1   0
+#define CPUCFG2_LEXT2   1
+#define CPUCFG2_LEXT3   2
+#define CPUCFG2_LSPW    3
+#define CPUCFG2_LCSRP   27
+#define CPUCFG2_LDISBLIKELY 28
 
     /* We waste some space so we can handle shadow registers like TCs. */
     TCState tcs[MIPS_SHADOW_SET_MAX];
@@ -1156,6 +1186,12 @@ typedef struct CPUArchState {
     void *irq[8];
     struct MIPSITUState *itu;
     MemoryRegion *itc_tag; /* ITC Configuration Tags */
+
+    /* Loongson IOCSR memory */
+    struct {
+        AddressSpace as;
+        MemoryRegion mr;
+    } iocsr;
 #endif
 
     const mips_def_t *cpu_model;
@@ -1281,6 +1317,12 @@ static inline bool ase_msa_available(CPUMIPSState *env)
     return env->CP0_Config3 & (1 << CP0C3_MSAP);
 }
 
+/* Check presence of Loongson CSR instructions */
+static inline bool ase_lcsr_available(CPUMIPSState *env)
+{
+    return env->lcsr_cpucfg2 & (1 << CPUCFG2_LCSRP);
+}
+
 /* Check presence of multi-threading ASE implementation */
 static inline bool ase_mt_available(CPUMIPSState *env)
 {

target/mips/helper.h

@@ -196,6 +196,10 @@ DEF_HELPER_1(rdhwr_xnp, tl, env)
 DEF_HELPER_2(pmon, void, env, int)
 DEF_HELPER_1(wait, void, env)
 
+#ifdef TARGET_MIPS64
+DEF_HELPER_FLAGS_2(lcsr_cpucfg, TCG_CALL_NO_RWG_SE, tl, env, tl)
+#endif
+
 /* Loongson multimedia functions.  */
 DEF_HELPER_FLAGS_2(paddsh, TCG_CALL_NO_RWG_SE, i64, i64, i64)
 DEF_HELPER_FLAGS_2(paddush, TCG_CALL_NO_RWG_SE, i64, i64, i64)

target/mips/internal.h

@@ -79,6 +79,8 @@ struct mips_def_t {
     int32_t CP0_PageGrain_rw_bitmask;
     int32_t CP0_PageGrain;
     target_ulong CP0_EBaseWG_rw_bitmask;
+    uint32_t lcsr_cpucfg1;
+    uint32_t lcsr_cpucfg2;
     uint64_t insn_flags;
     enum mips_mmu_types mmu_type;
     int32_t SAARP;

target/mips/tcg/lcsr.decode

@@ -0,0 +1,17 @@
+# Loongson CSR instructions
+#
+# Copyright (C) 2023 Jiaxun Yang <jiaxun.yang@flygoat.com>
+#
+# SPDX-License-Identifier: LGPL-2.1-or-later
+#
+
+&r           rs rt rd sa
+
+@rs_rd       ...... rs:5 ..... rd:5 ..... ...... &r rt=0 sa=0
+
+CPUCFG       110010 ..... 01000 ..... 00100 011000 @rs_rd
+
+RDCSR        110010 ..... 00000 ..... 00100 011000 @rs_rd
+WRCSR        110010 ..... 00001 ..... 00100 011000 @rs_rd
+DRDCSR       110010 ..... 00010 ..... 00100 011000 @rs_rd
+DWRCSR       110010 ..... 00011 ..... 00100 011000 @rs_rd

target/mips/tcg/lcsr_translate.c

@@ -0,0 +1,75 @@
+/*
+ * Loongson CSR instructions translation routines
+ *
+ *  Copyright (c) 2023 Jiaxun Yang <jiaxun.yang@flygoat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "cpu.h"
+#include "tcg/tcg-op.h"
+#include "tcg/tcg-op-gvec.h"
+#include "exec/helper-gen.h"
+#include "translate.h"
+
+/* Include the auto-generated decoder.  */
+#include "decode-lcsr.c.inc"
+
+static bool trans_CPUCFG(DisasContext *ctx, arg_CPUCFG *a)
+{
+    TCGv dest = tcg_temp_new();
+    TCGv src1 = tcg_temp_new();
+
+    gen_load_gpr(src1, a->rs);
+    gen_helper_lcsr_cpucfg(dest, cpu_env, src1);
+    gen_store_gpr(dest, a->rd);
+
+    return true;
+}
+
+#ifndef CONFIG_USER_ONLY
+static bool gen_rdcsr(DisasContext *ctx, arg_r *a,
+                        void (*func)(TCGv, TCGv_ptr, TCGv))
+{
+    TCGv dest = tcg_temp_new();
+    TCGv src1 = tcg_temp_new();
+
+    check_cp0_enabled(ctx);
+    gen_load_gpr(src1, a->rs);
+    func(dest, cpu_env, src1);
+    gen_store_gpr(dest, a->rd);
+
+    return true;
+}
+
+static bool gen_wrcsr(DisasContext *ctx, arg_r *a,
+                        void (*func)(TCGv_ptr, TCGv, TCGv))
+{
+    TCGv val = tcg_temp_new();
+    TCGv addr = tcg_temp_new();
+
+    check_cp0_enabled(ctx);
+    gen_load_gpr(addr, a->rs);
+    gen_load_gpr(val, a->rd);
+    func(cpu_env, addr, val);
+
+    return true;
+}
+
+TRANS(RDCSR, gen_rdcsr, gen_helper_lcsr_rdcsr)
+TRANS(DRDCSR, gen_rdcsr, gen_helper_lcsr_drdcsr)
+TRANS(WRCSR, gen_wrcsr, gen_helper_lcsr_wrcsr)
+TRANS(DWRCSR, gen_wrcsr, gen_helper_lcsr_dwrcsr)
+#else
+#define GEN_FALSE_TRANS(name)   \
+static bool trans_##name(DisasContext *ctx, arg_##name * a)  \
+{   \
+    return false;   \
+}
+
+GEN_FALSE_TRANS(RDCSR)
+GEN_FALSE_TRANS(DRDCSR)
+GEN_FALSE_TRANS(WRCSR)
+GEN_FALSE_TRANS(DWRCSR)
+#endif

target/mips/tcg/meson.build

@@ -4,6 +4,7 @@ gen = [
   decodetree.process('tx79.decode', extra_args: '--static-decode=decode_tx79'),
   decodetree.process('vr54xx.decode', extra_args: '--decode=decode_ext_vr54xx'),
   decodetree.process('octeon.decode', extra_args: '--decode=decode_ext_octeon'),
+  decodetree.process('lcsr.decode', extra_args: '--decode=decode_ase_lcsr'),
 ]
 
 mips_ss.add(gen)
@@ -26,6 +27,7 @@ mips_ss.add(files(
 mips_ss.add(when: 'TARGET_MIPS64', if_true: files(
   'tx79_translate.c',
   'octeon_translate.c',
+  'lcsr_translate.c',
 ), if_false: files(
   'mxu_translate.c',
 ))

target/mips/tcg/op_helper.c

@@ -257,6 +257,22 @@ void helper_pmon(CPUMIPSState *env, int function)
     }
 }
 
+#ifdef TARGET_MIPS64
+target_ulong helper_lcsr_cpucfg(CPUMIPSState *env, target_ulong rs)
+{
+    switch (rs) {
+    case 0:
+        return env->CP0_PRid;
+    case 1:
+        return env->lcsr_cpucfg1;
+    case 2:
+        return env->lcsr_cpucfg2;
+    default:
+        return 0;
+    }
+}
+#endif
+
 #if !defined(CONFIG_USER_ONLY)
 
 void mips_cpu_do_unaligned_access(CPUState *cs, vaddr addr,

target/mips/tcg/sysemu/lcsr_helper.c

@@ -0,0 +1,45 @@
+/*
+ * Loongson CSR instructions translation routines
+ *
+ *  Copyright (c) 2023 Jiaxun Yang <jiaxun.yang@flygoat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/main-loop.h"
+#include "cpu.h"
+#include "internal.h"
+#include "qemu/host-utils.h"
+#include "exec/helper-proto.h"
+#include "exec/exec-all.h"
+#include "exec/cpu_ldst.h"
+
+#define GET_MEMTXATTRS(cas) \
+        ((MemTxAttrs){.requester_id = env_cpu(cas)->cpu_index})
+
+uint64_t helper_lcsr_rdcsr(CPUMIPSState *env, target_ulong r_addr)
+{
+    return address_space_ldl(&env->iocsr.as, r_addr,
+                             GET_MEMTXATTRS(env), NULL);
+}
+
+uint64_t helper_lcsr_drdcsr(CPUMIPSState *env, target_ulong r_addr)
+{
+    return address_space_ldq(&env->iocsr.as, r_addr,
+                             GET_MEMTXATTRS(env), NULL);
+}
+
+void helper_lcsr_wrcsr(CPUMIPSState *env, target_ulong w_addr,
+                      target_ulong val)
+{
+    address_space_stl(&env->iocsr.as, w_addr,
+                      val, GET_MEMTXATTRS(env), NULL);
+}
+
+void helper_lcsr_dwrcsr(CPUMIPSState *env, target_ulong w_addr,
+                      target_ulong val)
+{
+    address_space_stq(&env->iocsr.as, w_addr,
+                      val, GET_MEMTXATTRS(env), NULL);
+}

target/mips/tcg/sysemu/meson.build

@@ -4,3 +4,7 @@ mips_system_ss.add(files(
   'special_helper.c',
   'tlb_helper.c',
 ))
+
+mips_system_ss.add(when: 'TARGET_MIPS64', if_true: files(
+  'lcsr_helper.c',
+))

target/mips/tcg/sysemu_helper.h.inc

@@ -181,3 +181,11 @@ DEF_HELPER_1(eret, void, env)
 DEF_HELPER_1(eretnc, void, env)
 DEF_HELPER_1(deret, void, env)
 DEF_HELPER_3(cache, void, env, tl, i32)
+
+#ifdef TARGET_MIPS64
+/* Longson CSR */
+DEF_HELPER_2(lcsr_rdcsr, i64, env, tl)
+DEF_HELPER_2(lcsr_drdcsr, i64, env, tl)
+DEF_HELPER_3(lcsr_wrcsr, void, env, tl, tl)
+DEF_HELPER_3(lcsr_dwrcsr, void, env, tl, tl)
+#endif

target/mips/tcg/translate.c

@@ -15352,6 +15352,9 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
         return;
     }
 #if defined(TARGET_MIPS64)
+    if (ase_lcsr_available(env) && decode_ase_lcsr(ctx, ctx->opcode)) {
+        return;
+    }
     if (cpu_supports_isa(env, INSN_OCTEON) && decode_ext_octeon(ctx, ctx->opcode)) {
         return;
     }

target/mips/tcg/translate.h

@@ -221,6 +221,7 @@ bool decode_isa_rel6(DisasContext *ctx, uint32_t insn);
 bool decode_ase_msa(DisasContext *ctx, uint32_t insn);
 bool decode_ext_txx9(DisasContext *ctx, uint32_t insn);
 #if defined(TARGET_MIPS64)
+bool decode_ase_lcsr(DisasContext *ctx, uint32_t insn);
 bool decode_ext_tx79(DisasContext *ctx, uint32_t insn);
 bool decode_ext_octeon(DisasContext *ctx, uint32_t insn);
 #endif