target/riscv: Make PMP region count configurable

Previously, the number of PMP regions was hardcoded to 16 in QEMU.
This patch replaces the fixed value with a new `pmp_regions` field,
allowing platforms to configure the number of PMP regions.

If no specific value is provided, the default number of PMP regions
remains 16 to preserve the existing behavior.

A new CPU parameter num-pmp-regions has been introduced to the QEMU
command line. For example:

	-cpu rv64, g=true, c=true, pmp=true, num-pmp-regions=8

Signed-off-by: Jay Chang <jay.chang@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20250606072525.17313-3-jay.chang@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

6 files changed, 74 insertions, 14 deletions

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index bf14256..758f254 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1119,6 +1119,7 @@ static void riscv_cpu_init(Object *obj)
     cpu->cfg.cbom_blocksize = 64;
     cpu->cfg.cbop_blocksize = 64;
     cpu->cfg.cboz_blocksize = 64;
+    cpu->cfg.pmp_regions = 16;
     cpu->env.vext_ver = VEXT_VERSION_1_00_0;
     cpu->cfg.max_satp_mode = -1;
 
@@ -1563,6 +1564,46 @@ static const PropertyInfo prop_pmp = {
     .set = prop_pmp_set,
 };
 
+static void prop_num_pmp_regions_set(Object *obj, Visitor *v, const char *name,
+                                     void *opaque, Error **errp)
+{
+    RISCVCPU *cpu = RISCV_CPU(obj);
+    uint8_t value;
+
+    visit_type_uint8(v, name, &value, errp);
+
+    if (cpu->cfg.pmp_regions != value && riscv_cpu_is_vendor(obj)) {
+        cpu_set_prop_err(cpu, name, errp);
+        return;
+    }
+
+    if (cpu->env.priv_ver < PRIV_VERSION_1_12_0 && value > OLD_MAX_RISCV_PMPS) {
+        error_setg(errp, "Number of PMP regions exceeds maximum available");
+        return;
+    } else if (value > MAX_RISCV_PMPS) {
+        error_setg(errp, "Number of PMP regions exceeds maximum available");
+        return;
+    }
+
+    cpu_option_add_user_setting(name, value);
+    cpu->cfg.pmp_regions = value;
+}
+
+static void prop_num_pmp_regions_get(Object *obj, Visitor *v, const char *name,
+                                     void *opaque, Error **errp)
+{
+    uint8_t value = RISCV_CPU(obj)->cfg.pmp_regions;
+
+    visit_type_uint8(v, name, &value, errp);
+}
+
+static const PropertyInfo prop_num_pmp_regions = {
+    .type = "uint8",
+    .description = "num-pmp-regions",
+    .get = prop_num_pmp_regions_get,
+    .set = prop_num_pmp_regions_set,
+};
+
 static int priv_spec_from_str(const char *priv_spec_str)
 {
     int priv_version = -1;
@@ -2562,6 +2603,7 @@ static const Property riscv_cpu_properties[] = {
 
     {.name = "mmu", .info = &prop_mmu},
     {.name = "pmp", .info = &prop_pmp},
+    {.name = "num-pmp-regions", .info = &prop_num_pmp_regions},
 
     {.name = "priv_spec", .info = &prop_priv_spec},
     {.name = "vext_spec", .info = &prop_vext_spec},
@@ -2932,7 +2974,8 @@ static const TypeInfo riscv_cpu_type_infos[] = {
         .cfg.max_satp_mode = VM_1_10_MBARE,
         .cfg.ext_zifencei = true,
         .cfg.ext_zicsr = true,
-        .cfg.pmp = true
+        .cfg.pmp = true,
+        .cfg.pmp_regions = 8
     ),
 
     DEFINE_ABSTRACT_RISCV_CPU(TYPE_RISCV_CPU_SIFIVE_U, TYPE_RISCV_VENDOR_CPU,
@@ -2943,7 +2986,8 @@ static const TypeInfo riscv_cpu_type_infos[] = {
         .cfg.ext_zifencei = true,
         .cfg.ext_zicsr = true,
         .cfg.mmu = true,
-        .cfg.pmp = true
+        .cfg.pmp = true,
+        .cfg.pmp_regions = 8
     ),
 
 #if defined(TARGET_RISCV32) || \
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 17bf4e7..4a862da 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -174,7 +174,8 @@ extern RISCVCPUImpliedExtsRule *riscv_multi_ext_implied_rules[];
 
 #define MMU_USER_IDX 3
 
-#define MAX_RISCV_PMPS (16)
+#define MAX_RISCV_PMPS (64)
+#define OLD_MAX_RISCV_PMPS (16)
 
 #if !defined(CONFIG_USER_ONLY)
 #include "pmp.h"
diff --git a/target/riscv/cpu_cfg_fields.h.inc b/target/riscv/cpu_cfg_fields.h.inc
index 59f134a..33c4f9b 100644
--- a/target/riscv/cpu_cfg_fields.h.inc
+++ b/target/riscv/cpu_cfg_fields.h.inc
@@ -163,6 +163,7 @@ TYPED_FIELD(uint16_t, elen, 0)
 TYPED_FIELD(uint16_t, cbom_blocksize, 0)
 TYPED_FIELD(uint16_t, cbop_blocksize, 0)
 TYPED_FIELD(uint16_t, cboz_blocksize, 0)
+TYPED_FIELD(uint8_t,  pmp_regions, 0)
 
 TYPED_FIELD(int8_t, max_satp_mode, -1)
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index d6cd441..6296ecd 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -738,7 +738,10 @@ static RISCVException dbltrp_hmode(CPURISCVState *env, int csrno)
 static RISCVException pmp(CPURISCVState *env, int csrno)
 {
     if (riscv_cpu_cfg(env)->pmp) {
-        if (csrno <= CSR_PMPCFG3) {
+        int max_pmpcfg = (env->priv_ver >= PRIV_VERSION_1_12_0) ?
++                              CSR_PMPCFG15 : CSR_PMPCFG3;
+
+        if (csrno <= max_pmpcfg) {
             uint32_t reg_index = csrno - CSR_PMPCFG0;
 
             /* TODO: RV128 restriction check */
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index c97e9ce..1600ec4 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -36,8 +36,9 @@ static int pmp_post_load(void *opaque, int version_id)
     RISCVCPU *cpu = opaque;
     CPURISCVState *env = &cpu->env;
     int i;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
-    for (i = 0; i < MAX_RISCV_PMPS; i++) {
+    for (i = 0; i < pmp_regions; i++) {
         pmp_update_rule_addr(env, i);
     }
     pmp_update_rule_nums(env);
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 5af295e..3540327 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -122,7 +122,9 @@ uint32_t pmp_get_num_rules(CPURISCVState *env)
  */
 static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
 {
-    if (pmp_index < MAX_RISCV_PMPS) {
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
+
+    if (pmp_index < pmp_regions) {
         return env->pmp_state.pmp[pmp_index].cfg_reg;
     }
 
@@ -136,7 +138,9 @@ static inline uint8_t pmp_read_cfg(CPURISCVState *env, uint32_t pmp_index)
  */
 static bool pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
 {
-    if (pmp_index < MAX_RISCV_PMPS) {
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
+
+    if (pmp_index < pmp_regions) {
         if (env->pmp_state.pmp[pmp_index].cfg_reg == val) {
             /* no change */
             return false;
@@ -236,9 +240,10 @@ void pmp_update_rule_addr(CPURISCVState *env, uint32_t pmp_index)
 void pmp_update_rule_nums(CPURISCVState *env)
 {
     int i;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
     env->pmp_state.num_rules = 0;
-    for (i = 0; i < MAX_RISCV_PMPS; i++) {
+    for (i = 0; i < pmp_regions; i++) {
         const uint8_t a_field =
             pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg);
         if (PMP_AMATCH_OFF != a_field) {
@@ -332,6 +337,7 @@ bool pmp_hart_has_privs(CPURISCVState *env, hwaddr addr,
     int pmp_size = 0;
     hwaddr s = 0;
     hwaddr e = 0;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
     /* Short cut if no rules */
     if (0 == pmp_get_num_rules(env)) {
@@ -356,7 +362,7 @@ bool pmp_hart_has_privs(CPURISCVState *env, hwaddr addr,
      * 1.10 draft priv spec states there is an implicit order
      * from low to high
      */
-    for (i = 0; i < MAX_RISCV_PMPS; i++) {
+    for (i = 0; i < pmp_regions; i++) {
         s = pmp_is_in_range(env, i, addr);
         e = pmp_is_in_range(env, i, addr + pmp_size - 1);
 
@@ -527,8 +533,9 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
 {
     trace_pmpaddr_csr_write(env->mhartid, addr_index, val);
     bool is_next_cfg_tor = false;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
-    if (addr_index < MAX_RISCV_PMPS) {
+    if (addr_index < pmp_regions) {
         if (env->pmp_state.pmp[addr_index].addr_reg == val) {
             /* no change */
             return;
@@ -538,7 +545,7 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
          * In TOR mode, need to check the lock bit of the next pmp
          * (if there is a next).
          */
-        if (addr_index + 1 < MAX_RISCV_PMPS) {
+        if (addr_index + 1 < pmp_regions) {
             uint8_t pmp_cfg = env->pmp_state.pmp[addr_index + 1].cfg_reg;
             is_next_cfg_tor = PMP_AMATCH_TOR == pmp_get_a_field(pmp_cfg);
 
@@ -573,8 +580,9 @@ void pmpaddr_csr_write(CPURISCVState *env, uint32_t addr_index,
 target_ulong pmpaddr_csr_read(CPURISCVState *env, uint32_t addr_index)
 {
     target_ulong val = 0;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
-    if (addr_index < MAX_RISCV_PMPS) {
+    if (addr_index < pmp_regions) {
         val = env->pmp_state.pmp[addr_index].addr_reg;
         trace_pmpaddr_csr_read(env->mhartid, addr_index, val);
     } else {
@@ -592,6 +600,7 @@ void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
 {
     int i;
     uint64_t mask = MSECCFG_MMWP | MSECCFG_MML;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
     /* Update PMM field only if the value is valid according to Zjpm v1.0 */
     if (riscv_cpu_cfg(env)->ext_smmpm &&
         riscv_cpu_mxl(env) == MXL_RV64 &&
@@ -603,7 +612,7 @@ void mseccfg_csr_write(CPURISCVState *env, target_ulong val)
 
     /* RLB cannot be enabled if it's already 0 and if any regions are locked */
     if (!MSECCFG_RLB_ISSET(env)) {
-        for (i = 0; i < MAX_RISCV_PMPS; i++) {
+        for (i = 0; i < pmp_regions; i++) {
             if (pmp_is_locked(env, i)) {
                 val &= ~MSECCFG_RLB;
                 break;
@@ -659,6 +668,7 @@ target_ulong pmp_get_tlb_size(CPURISCVState *env, hwaddr addr)
     hwaddr tlb_sa = addr & ~(TARGET_PAGE_SIZE - 1);
     hwaddr tlb_ea = tlb_sa + TARGET_PAGE_SIZE - 1;
     int i;
+    uint8_t pmp_regions = riscv_cpu_cfg(env)->pmp_regions;
 
     /*
      * If PMP is not supported or there are no PMP rules, the TLB page will not
@@ -669,7 +679,7 @@ target_ulong pmp_get_tlb_size(CPURISCVState *env, hwaddr addr)
         return TARGET_PAGE_SIZE;
     }
 
-    for (i = 0; i < MAX_RISCV_PMPS; i++) {
+    for (i = 0; i < pmp_regions; i++) {
         if (pmp_get_a_field(env->pmp_state.pmp[i].cfg_reg) == PMP_AMATCH_OFF) {
             continue;
         }