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Re: [PATCH v6 8/9] target/riscv: remove RISCV_FEATURE_MMU


From: LIU Zhiwei
Subject: Re: [PATCH v6 8/9] target/riscv: remove RISCV_FEATURE_MMU
Date: Fri, 17 Feb 2023 10:04:22 +0800
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2


On 2023/2/17 5:55, Daniel Henrique Barboza wrote:
RISCV_FEATURE_MMU is set whether cpu->cfg.mmu is set, so let's just use
the flag directly instead.

With this change the enum is also removed. It is worth noticing that
this enum, and all the RISCV_FEATURES_* that were contained in it,
predates the existence of the cpu->cfg object. Today, using cpu->cfg is
an easier way to retrieve all the features and extensions enabled in the
hart.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
  target/riscv/cpu.c        | 4 ----
  target/riscv/cpu.h        | 7 -------
  target/riscv/cpu_helper.c | 2 +-
  target/riscv/csr.c        | 4 ++--
  target/riscv/monitor.c    | 2 +-
  target/riscv/pmp.c        | 2 +-
  6 files changed, 5 insertions(+), 16 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 7b1360d6ba..075033006c 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -919,10 +919,6 @@ static void riscv_cpu_realize(DeviceState *dev, Error 
**errp)
          }
      }
- if (cpu->cfg.mmu) {
-        riscv_set_feature(env, RISCV_FEATURE_MMU);
-    }
-
      if (cpu->cfg.epmp && !cpu->cfg.pmp) {
          /*
           * Enhanced PMP should only be available
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 119a022af9..0519d2ab0c 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -81,13 +81,6 @@
  #define RVH RV('H')
  #define RVJ RV('J')
-/* S extension denotes that Supervisor mode exists, however it is possible
-   to have a core that support S mode but does not have an MMU and there
-   is currently no bit in misa to indicate whether an MMU exists or not
-   so a cpu features bitfield is required, likewise for optional PMP support */
-enum {
-    RISCV_FEATURE_MMU,
-};
/* Privileged specification version */
  enum {
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 292b6b3168..eda2293470 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -796,7 +796,7 @@ static int get_physical_address(CPURISCVState *env, hwaddr 
*physical,
          mode = PRV_U;
      }
- if (mode == PRV_M || !riscv_feature(env, RISCV_FEATURE_MMU)) {
+    if (mode == PRV_M || !riscv_cpu_cfg(env)->mmu) {
          *physical = addr;
          *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
          return TRANSLATE_SUCCESS;
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index d0ab00d870..fcc271c93c 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -2569,7 +2569,7 @@ static RISCVException rmw_siph(CPURISCVState *env, int 
csrno,
  static RISCVException read_satp(CPURISCVState *env, int csrno,
                                  target_ulong *val)
  {
-    if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
+    if (!riscv_cpu_cfg(env)->mmu) {
          *val = 0;
          return RISCV_EXCP_NONE;
      }
@@ -2588,7 +2588,7 @@ static RISCVException write_satp(CPURISCVState *env, int 
csrno,
  {
      target_ulong vm, mask;
- if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
+    if (!riscv_cpu_cfg(env)->mmu) {
          return RISCV_EXCP_NONE;
      }
diff --git a/target/riscv/monitor.c b/target/riscv/monitor.c
index 236f93b9f5..f36ddfa967 100644
--- a/target/riscv/monitor.c
+++ b/target/riscv/monitor.c
@@ -218,7 +218,7 @@ void hmp_info_mem(Monitor *mon, const QDict *qdict)
          return;
      }
- if (!riscv_feature(env, RISCV_FEATURE_MMU)) {
+    if (!riscv_cpu_cfg(env)->mmu) {
          monitor_printf(mon, "S-mode MMU unavailable\n");
          return;
      }
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 205bfbe090..a08cd95658 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -315,7 +315,7 @@ int pmp_hart_has_privs(CPURISCVState *env, target_ulong 
addr,
      }
if (size == 0) {
-        if (riscv_feature(env, RISCV_FEATURE_MMU)) {
+        if (riscv_cpu_cfg(env)->mmu) {

Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>

Zhiwei

              /*
               * If size is unknown (0), assume that all bytes
               * from addr to the end of the page will be accessed.



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