target/riscv: Support CSRs required for RISC-V PM extension except for the h-mode

Signed-off-by: Alexey Baturo <space.monkey.delivers@gmail.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20211025173609.2724490-4-space.monkey.delivers@gmail.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -367,6 +367,8 @@ static void riscv_cpu_reset(DeviceState *dev)
     env->mcause = 0;
     env->pc = env->resetvec;
     env->two_stage_lookup = false;
+    /* mmte is supposed to have pm.current hardwired to 1 */
+    env->mmte |= (PM_EXT_INITIAL | MMTE_M_PM_CURRENT);
 #endif
     cs->exception_index = RISCV_EXCP_NONE;
     env->load_res = -1;

target/riscv/cpu.h

@@ -238,6 +238,17 @@ struct CPURISCVState {
 
     /* True if in debugger mode.  */
     bool debugger;
+
+    /*
+     * CSRs for PointerMasking extension
+     */
+    target_ulong mmte;
+    target_ulong mpmmask;
+    target_ulong mpmbase;
+    target_ulong spmmask;
+    target_ulong spmbase;
+    target_ulong upmmask;
+    target_ulong upmbase;
 #endif
 
     float_status fp_status;

target/riscv/csr.c

@@ -192,6 +192,16 @@ static RISCVException hmode32(CPURISCVState *env, int csrno)
 
 }
 
+/* Checks if PointerMasking registers could be accessed */
+static RISCVException pointer_masking(CPURISCVState *env, int csrno)
+{
+    /* Check if j-ext is present */
+    if (riscv_has_ext(env, RVJ)) {
+        return RISCV_EXCP_NONE;
+    }
+    return RISCV_EXCP_ILLEGAL_INST;
+}
+
 static RISCVException pmp(CPURISCVState *env, int csrno)
 {
     if (riscv_feature(env, RISCV_FEATURE_PMP)) {
@@ -1425,6 +1435,268 @@ static RISCVException write_pmpaddr(CPURISCVState *env, int csrno,
     return RISCV_EXCP_NONE;
 }
 
+/*
+ * Functions to access Pointer Masking feature registers
+ * We have to check if current priv lvl could modify
+ * csr in given mode
+ */
+static bool check_pm_current_disabled(CPURISCVState *env, int csrno)
+{
+    int csr_priv = get_field(csrno, 0x300);
+    int pm_current;
+
+    /*
+     * If priv lvls differ that means we're accessing csr from higher priv lvl,
+     * so allow the access
+     */
+    if (env->priv != csr_priv) {
+        return false;
+    }
+    switch (env->priv) {
+    case PRV_M:
+        pm_current = get_field(env->mmte, M_PM_CURRENT);
+        break;
+    case PRV_S:
+        pm_current = get_field(env->mmte, S_PM_CURRENT);
+        break;
+    case PRV_U:
+        pm_current = get_field(env->mmte, U_PM_CURRENT);
+        break;
+    default:
+        g_assert_not_reached();
+    }
+    /* It's same priv lvl, so we allow to modify csr only if pm.current==1 */
+    return !pm_current;
+}
+
+static RISCVException read_mmte(CPURISCVState *env, int csrno,
+                                target_ulong *val)
+{
+    *val = env->mmte & MMTE_MASK;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_mmte(CPURISCVState *env, int csrno,
+                                 target_ulong val)
+{
+    uint64_t mstatus;
+    target_ulong wpri_val = val & MMTE_MASK;
+
+    if (val != wpri_val) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s" TARGET_FMT_lx " %s" TARGET_FMT_lx "\n",
+                      "MMTE: WPRI violation written 0x", val,
+                      "vs expected 0x", wpri_val);
+    }
+    /* for machine mode pm.current is hardwired to 1 */
+    wpri_val |= MMTE_M_PM_CURRENT;
+
+    /* hardwiring pm.instruction bit to 0, since it's not supported yet */
+    wpri_val &= ~(MMTE_M_PM_INSN | MMTE_S_PM_INSN | MMTE_U_PM_INSN);
+    env->mmte = wpri_val | PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_smte(CPURISCVState *env, int csrno,
+                                target_ulong *val)
+{
+    *val = env->mmte & SMTE_MASK;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_smte(CPURISCVState *env, int csrno,
+                                 target_ulong val)
+{
+    target_ulong wpri_val = val & SMTE_MASK;
+
+    if (val != wpri_val) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s" TARGET_FMT_lx " %s" TARGET_FMT_lx "\n",
+                      "SMTE: WPRI violation written 0x", val,
+                      "vs expected 0x", wpri_val);
+    }
+
+    /* if pm.current==0 we can't modify current PM CSRs */
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+
+    wpri_val |= (env->mmte & ~SMTE_MASK);
+    write_mmte(env, csrno, wpri_val);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_umte(CPURISCVState *env, int csrno,
+                                target_ulong *val)
+{
+    *val = env->mmte & UMTE_MASK;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_umte(CPURISCVState *env, int csrno,
+                                 target_ulong val)
+{
+    target_ulong wpri_val = val & UMTE_MASK;
+
+    if (val != wpri_val) {
+        qemu_log_mask(LOG_GUEST_ERROR, "%s" TARGET_FMT_lx " %s" TARGET_FMT_lx "\n",
+                      "UMTE: WPRI violation written 0x", val,
+                      "vs expected 0x", wpri_val);
+    }
+
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+
+    wpri_val |= (env->mmte & ~UMTE_MASK);
+    write_mmte(env, csrno, wpri_val);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_mpmmask(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->mpmmask;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_mpmmask(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    env->mpmmask = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_spmmask(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->spmmask;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_spmmask(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    /* if pm.current==0 we can't modify current PM CSRs */
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+    env->spmmask = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_upmmask(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->upmmask;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_upmmask(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    /* if pm.current==0 we can't modify current PM CSRs */
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+    env->upmmask = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_mpmbase(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->mpmbase;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_mpmbase(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    env->mpmbase = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_spmbase(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->spmbase;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_spmbase(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    /* if pm.current==0 we can't modify current PM CSRs */
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+    env->spmbase = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException read_upmbase(CPURISCVState *env, int csrno,
+                                   target_ulong *val)
+{
+    *val = env->upmbase;
+    return RISCV_EXCP_NONE;
+}
+
+static RISCVException write_upmbase(CPURISCVState *env, int csrno,
+                                    target_ulong val)
+{
+    uint64_t mstatus;
+
+    /* if pm.current==0 we can't modify current PM CSRs */
+    if (check_pm_current_disabled(env, csrno)) {
+        return RISCV_EXCP_NONE;
+    }
+    env->upmbase = val;
+    env->mmte |= PM_EXT_DIRTY;
+
+    /* Set XS and SD bits, since PM CSRs are dirty */
+    mstatus = env->mstatus | MSTATUS_XS;
+    write_mstatus(env, csrno, mstatus);
+    return RISCV_EXCP_NONE;
+}
+
 #endif
 
 /*
@@ -1659,6 +1931,19 @@ riscv_csr_operations csr_ops[CSR_TABLE_SIZE] = {
     [CSR_PMPADDR14] =  { "pmpaddr14", pmp, read_pmpaddr, write_pmpaddr },
     [CSR_PMPADDR15] =  { "pmpaddr15", pmp, read_pmpaddr, write_pmpaddr },
 
+    /* User Pointer Masking */
+    [CSR_UMTE]    =    { "umte",    pointer_masking, read_umte,    write_umte    },
+    [CSR_UPMMASK] =    { "upmmask", pointer_masking, read_upmmask, write_upmmask },
+    [CSR_UPMBASE] =    { "upmbase", pointer_masking, read_upmbase, write_upmbase },
+    /* Machine Pointer Masking */
+    [CSR_MMTE]    =    { "mmte",    pointer_masking, read_mmte,    write_mmte    },
+    [CSR_MPMMASK] =    { "mpmmask", pointer_masking, read_mpmmask, write_mpmmask },
+    [CSR_MPMBASE] =    { "mpmbase", pointer_masking, read_mpmbase, write_mpmbase },
+    /* Supervisor Pointer Masking */
+    [CSR_SMTE]    =    { "smte",    pointer_masking, read_smte,    write_smte    },
+    [CSR_SPMMASK] =    { "spmmask", pointer_masking, read_spmmask, write_spmmask },
+    [CSR_SPMBASE] =    { "spmbase", pointer_masking, read_spmbase, write_spmbase },
+
     /* Performance Counters */
     [CSR_HPMCOUNTER3]    = { "hpmcounter3",    ctr,    read_zero },
     [CSR_HPMCOUNTER4]    = { "hpmcounter4",    ctr,    read_zero },