[PATCH v5 0/9] make write_misa a no-op and FEATURE_* cleanups

[PATCH v5 0/9] make write_misa a no-op and FEATURE_* cleanups

[Daniel Henrique Barboza]

Hi,

This new version squashed patches 1 and 2 together and there's more
detail in patch 1 about why we're not violating the spec by keeping
write_misa() as a no-op.

All patches are acked.

Changes from v4:
- patches 1 and 2 from v4: squashed together
- patch 1:
  - added more detail in the commit msg about why a no-op misa write is
    spec compliant
- v4 link: https://lists.gnu.org/archive/html/qemu-devel/2023-02/msg04780.html

Daniel Henrique Barboza (9):
  target/riscv: turn write_misa() into an official no-op
  target/riscv: introduce riscv_cpu_cfg()
  target/riscv: remove RISCV_FEATURE_DEBUG
  target/riscv/cpu.c: error out if EPMP is enabled without PMP
  target/riscv: remove RISCV_FEATURE_EPMP
  target/riscv: remove RISCV_FEATURE_PMP
  hw/riscv/virt.c: do not use RISCV_FEATURE_MMU in
    create_fdt_socket_cpus()
  target/riscv: remove RISCV_FEATURE_MMU
  target/riscv/cpu: remove CPUArchState::features and friends

 hw/riscv/virt.c           |  7 +++--
 target/riscv/cpu.c        | 19 +++---------
 target/riscv/cpu.h        | 28 +++--------------
 target/riscv/cpu_helper.c |  6 ++--
 target/riscv/csr.c        | 65 +++------------------------------------
 target/riscv/machine.c    | 11 +++----
 target/riscv/monitor.c    |  2 +-
 target/riscv/op_helper.c  |  2 +-
 target/riscv/pmp.c        |  8 ++---
 9 files changed, 31 insertions(+), 117 deletions(-)

-- 
2.39.1

[PATCH v5 1/9] target/riscv: turn write_misa() into an official no-op

[Daniel Henrique Barboza]

At this moment, and apparently since ever, we have no way of enabling
RISCV_FEATURE_MISA. This means that all the code from write_misa(), all
the nuts and bolts that handles how to write this CSR, has always been a
no-op as well because write_misa() will always exit earlier.

This seems to be benign in the majority of cases. Booting an Ubuntu
'virt' guest and logging all the calls to 'write_misa' shows that no
writes to MISA CSR was attempted. Writing MISA, i.e. enabling/disabling
RISC-V extensions after the machine is powered on, seems to be a niche
use.

Before proceeding, let's recap what the spec says about MISA. It is a
CSR that is divided in 3 fields:

- MXL, Machine XLEN, described as "may be writable";

- MXLEN, the XLEN in M-mode, which is given by the setting of MXL or a
fixed value if MISA is zero;

- Extensions is defined as "a WARL field that can contain writable bits
where the implementation allows the supported ISA to be modified"

Thus what we have today (write_misa() being a no-op) is already a valid
spec implementation. We're not obliged to have a particular set of MISA
writable bits, and at this moment we have none.

Given that allowing the dormant code to write MISA can cause tricky bugs
to solve later on, and we don't have a particularly interesting case of
writing MISA to support today, and we're already not violating the
specification, let's erase all the body of write_misa() and turn it into
an official no-op instead of an accidental one. We'll keep consistent
with what we provide users today but with 50+ less lines to maintain.

RISCV_FEATURE_MISA enum is erased in the process since there's no one
else using it.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Bin Meng <bmeng@tinylab.org>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
---
 target/riscv/cpu.h |  1 -
 target/riscv/csr.c | 55 ----------------------------------------------
 2 files changed, 56 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 7128438d8e..01803a020d 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -89,7 +89,6 @@ enum {
     RISCV_FEATURE_MMU,
     RISCV_FEATURE_PMP,
     RISCV_FEATURE_EPMP,
-    RISCV_FEATURE_MISA,
     RISCV_FEATURE_DEBUG
 };
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 1b0a0c1693..f7862ff4a4 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1329,61 +1329,6 @@ static RISCVException read_misa(CPURISCVState *env, int csrno,
 static RISCVException write_misa(CPURISCVState *env, int csrno,
                                  target_ulong val)
 {
-    if (!riscv_feature(env, RISCV_FEATURE_MISA)) {
-        /* drop write to misa */
-        return RISCV_EXCP_NONE;
-    }
-
-    /* 'I' or 'E' must be present */
-    if (!(val & (RVI | RVE))) {
-        /* It is not, drop write to misa */
-        return RISCV_EXCP_NONE;
-    }
-
-    /* 'E' excludes all other extensions */
-    if (val & RVE) {
-        /* when we support 'E' we can do "val = RVE;" however
-         * for now we just drop writes if 'E' is present.
-         */
-        return RISCV_EXCP_NONE;
-    }
-
-    /*
-     * misa.MXL writes are not supported by QEMU.
-     * Drop writes to those bits.
-     */
-
-    /* Mask extensions that are not supported by this hart */
-    val &= env->misa_ext_mask;
-
-    /* Mask extensions that are not supported by QEMU */
-    val &= (RVI | RVE | RVM | RVA | RVF | RVD | RVC | RVS | RVU | RVV);
-
-    /* 'D' depends on 'F', so clear 'D' if 'F' is not present */
-    if ((val & RVD) && !(val & RVF)) {
-        val &= ~RVD;
-    }
-
-    /* Suppress 'C' if next instruction is not aligned
-     * TODO: this should check next_pc
-     */
-    if ((val & RVC) && (GETPC() & ~3) != 0) {
-        val &= ~RVC;
-    }
-
-    /* If nothing changed, do nothing. */
-    if (val == env->misa_ext) {
-        return RISCV_EXCP_NONE;
-    }
-
-    if (!(val & RVF)) {
-        env->mstatus &= ~MSTATUS_FS;
-    }
-
-    /* flush translation cache */
-    tb_flush(env_cpu(env));
-    env->misa_ext = val;
-    env->xl = riscv_cpu_mxl(env);
     return RISCV_EXCP_NONE;
 }
 
-- 
2.39.1

[PATCH v5 2/9] target/riscv: introduce riscv_cpu_cfg()

[Daniel Henrique Barboza]

We're going to do changes that requires accessing the RISCVCPUConfig
struct from the RISCVCPU, having access only to a CPURISCVState 'env'
pointer. Add a helper to make the code easier to read.

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.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 01803a020d..368a522b5b 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -653,6 +653,11 @@ static inline RISCVMXL riscv_cpu_mxl(CPURISCVState *env)
 #endif
 #define riscv_cpu_mxl_bits(env) (1UL << (4 + riscv_cpu_mxl(env)))
 
+static inline RISCVCPUConfig riscv_cpu_cfg(CPURISCVState *env)
+{
+    return env_archcpu(env)->cfg;
+}
+
 #if defined(TARGET_RISCV32)
 #define cpu_recompute_xl(env)  ((void)(env), MXL_RV32)
 #else
-- 
2.39.1

[PATCH v5 3/9] target/riscv: remove RISCV_FEATURE_DEBUG

[Daniel Henrique Barboza]

RISCV_FEATURE_DEBUG will always follow the value defined by
cpu->cfg.debug flag. Read the flag instead.

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        | 6 +-----
 target/riscv/cpu.h        | 1 -
 target/riscv/cpu_helper.c | 2 +-
 target/riscv/csr.c        | 2 +-
 target/riscv/machine.c    | 3 +--
 5 files changed, 4 insertions(+), 10 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 93b52b826c..e34a5e3f11 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -637,7 +637,7 @@ static void riscv_cpu_reset_hold(Object *obj)
     set_default_nan_mode(1, &env->fp_status);
 
 #ifndef CONFIG_USER_ONLY
-    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+    if (cpu->cfg.debug) {
         riscv_trigger_init(env);
     }
 
@@ -935,10 +935,6 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
         }
     }
 
-    if (cpu->cfg.debug) {
-        riscv_set_feature(env, RISCV_FEATURE_DEBUG);
-    }
-
 
 #ifndef CONFIG_USER_ONLY
     if (cpu->cfg.ext_sstc) {
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 368a522b5b..7326aaed27 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -89,7 +89,6 @@ enum {
     RISCV_FEATURE_MMU,
     RISCV_FEATURE_PMP,
     RISCV_FEATURE_EPMP,
-    RISCV_FEATURE_DEBUG
 };
 
 /* Privileged specification version */
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index ad8d82662c..4cdd247c6c 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -105,7 +105,7 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, target_ulong *pc,
         flags = FIELD_DP32(flags, TB_FLAGS, MSTATUS_HS_VS,
                            get_field(env->mstatus_hs, MSTATUS_VS));
     }
-    if (riscv_feature(env, RISCV_FEATURE_DEBUG) && !icount_enabled()) {
+    if (cpu->cfg.debug && !icount_enabled()) {
         flags = FIELD_DP32(flags, TB_FLAGS, ITRIGGER, env->itrigger_enabled);
     }
 #endif
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index f7862ff4a4..90dc28e22e 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -437,7 +437,7 @@ static RISCVException epmp(CPURISCVState *env, int csrno)
 
 static RISCVException debug(CPURISCVState *env, int csrno)
 {
-    if (riscv_feature(env, RISCV_FEATURE_DEBUG)) {
+    if (riscv_cpu_cfg(env).debug) {
         return RISCV_EXCP_NONE;
     }
 
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index c6ce318cce..4634968898 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -226,9 +226,8 @@ static const VMStateDescription vmstate_kvmtimer = {
 static bool debug_needed(void *opaque)
 {
     RISCVCPU *cpu = opaque;
-    CPURISCVState *env = &cpu->env;
 
-    return riscv_feature(env, RISCV_FEATURE_DEBUG);
+    return cpu->cfg.debug;
 }
 
 static int debug_post_load(void *opaque, int version_id)
-- 
2.39.1

[PATCH v5 4/9] target/riscv/cpu.c: error out if EPMP is enabled without PMP

[Daniel Henrique Barboza]

Instead of silently ignoring the EPMP setting if there is no PMP
available, error out informing the user that EPMP depends on PMP
support:

$ ./qemu-system-riscv64 -cpu rv64,pmp=false,x-epmp=true
qemu-system-riscv64: Invalid configuration: EPMP requires PMP support

This will force users to pick saner options in the QEMU command line.

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 | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index e34a5e3f11..4585ca74dc 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -925,13 +925,18 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
 
     if (cpu->cfg.pmp) {
         riscv_set_feature(env, RISCV_FEATURE_PMP);
+    }
+
+    if (cpu->cfg.epmp) {
+        riscv_set_feature(env, RISCV_FEATURE_EPMP);
 
         /*
          * Enhanced PMP should only be available
          * on harts with PMP support
          */
-        if (cpu->cfg.epmp) {
-            riscv_set_feature(env, RISCV_FEATURE_EPMP);
+        if (!cpu->cfg.pmp) {
+            error_setg(errp, "Invalid configuration: EPMP requires PMP support");
+            return;
         }
     }
 
-- 
2.39.1

[PATCH v5 5/9] target/riscv: remove RISCV_FEATURE_EPMP

[Daniel Henrique Barboza]

RISCV_FEATURE_EPMP is always set to the same value as the cpu->cfg.epmp
flag. Use the flag directly.

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 | 10 +++-------
 target/riscv/cpu.h |  1 -
 target/riscv/csr.c |  2 +-
 target/riscv/pmp.c |  4 ++--
 4 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 4585ca74dc..71b2042d73 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -927,17 +927,13 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
         riscv_set_feature(env, RISCV_FEATURE_PMP);
     }
 
-    if (cpu->cfg.epmp) {
-        riscv_set_feature(env, RISCV_FEATURE_EPMP);
-
+    if (cpu->cfg.epmp && !cpu->cfg.pmp) {
         /*
          * Enhanced PMP should only be available
          * on harts with PMP support
          */
-        if (!cpu->cfg.pmp) {
-            error_setg(errp, "Invalid configuration: EPMP requires PMP support");
-            return;
-        }
+        error_setg(errp, "Invalid configuration: EPMP requires PMP support");
+        return;
     }
 
 
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 7326aaed27..c87e50e804 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -88,7 +88,6 @@
 enum {
     RISCV_FEATURE_MMU,
     RISCV_FEATURE_PMP,
-    RISCV_FEATURE_EPMP,
 };
 
 /* Privileged specification version */
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 90dc28e22e..3a2e85918a 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -428,7 +428,7 @@ static RISCVException pmp(CPURISCVState *env, int csrno)
 
 static RISCVException epmp(CPURISCVState *env, int csrno)
 {
-    if (env->priv == PRV_M && riscv_feature(env, RISCV_FEATURE_EPMP)) {
+    if (env->priv == PRV_M && riscv_cpu_cfg(env).epmp) {
         return RISCV_EXCP_NONE;
     }
 
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index 4bc4113531..bb54899635 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -88,7 +88,7 @@ static void pmp_write_cfg(CPURISCVState *env, uint32_t pmp_index, uint8_t val)
     if (pmp_index < MAX_RISCV_PMPS) {
         bool locked = true;
 
-        if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
+        if (riscv_cpu_cfg(env).epmp) {
             /* mseccfg.RLB is set */
             if (MSECCFG_RLB_ISSET(env)) {
                 locked = false;
@@ -239,7 +239,7 @@ static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr,
 {
     bool ret;
 
-    if (riscv_feature(env, RISCV_FEATURE_EPMP)) {
+    if (riscv_cpu_cfg(env).epmp) {
         if (MSECCFG_MMWP_ISSET(env)) {
             /*
              * The Machine Mode Whitelist Policy (mseccfg.MMWP) is set
-- 
2.39.1

[PATCH v5 6/9] target/riscv: remove RISCV_FEATURE_PMP

[Daniel Henrique Barboza]

RISCV_FEATURE_PMP is being set via riscv_set_feature() by mirroring the
cpu->cfg.pmp flag. Use the flag instead.

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        | 1 -
 target/riscv/cpu_helper.c | 2 +-
 target/riscv/csr.c        | 2 +-
 target/riscv/machine.c    | 3 +--
 target/riscv/op_helper.c  | 2 +-
 target/riscv/pmp.c        | 2 +-
 7 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 71b2042d73..7b1360d6ba 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -923,10 +923,6 @@ static void riscv_cpu_realize(DeviceState *dev, Error **errp)
         riscv_set_feature(env, RISCV_FEATURE_MMU);
     }
 
-    if (cpu->cfg.pmp) {
-        riscv_set_feature(env, RISCV_FEATURE_PMP);
-    }
-
     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 c87e50e804..bd7ab5fceb 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -87,7 +87,6 @@
    so a cpu features bitfield is required, likewise for optional PMP support */
 enum {
     RISCV_FEATURE_MMU,
-    RISCV_FEATURE_PMP,
 };
 
 /* Privileged specification version */
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 4cdd247c6c..15d9542691 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -706,7 +706,7 @@ static int get_physical_address_pmp(CPURISCVState *env, int *prot,
     pmp_priv_t pmp_priv;
     int pmp_index = -1;
 
-    if (!riscv_feature(env, RISCV_FEATURE_PMP)) {
+    if (!riscv_cpu_cfg(env).pmp) {
         *prot = PAGE_READ | PAGE_WRITE | PAGE_EXEC;
         return TRANSLATE_SUCCESS;
     }
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 3a2e85918a..a8a7d0aa34 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -419,7 +419,7 @@ static int aia_hmode32(CPURISCVState *env, int csrno)
 
 static RISCVException pmp(CPURISCVState *env, int csrno)
 {
-    if (riscv_feature(env, RISCV_FEATURE_PMP)) {
+    if (riscv_cpu_cfg(env).pmp) {
         return RISCV_EXCP_NONE;
     }
 
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index 4634968898..67e9e56853 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -27,9 +27,8 @@
 static bool pmp_needed(void *opaque)
 {
     RISCVCPU *cpu = opaque;
-    CPURISCVState *env = &cpu->env;
 
-    return riscv_feature(env, RISCV_FEATURE_PMP);
+    return cpu->cfg.pmp;
 }
 
 static int pmp_post_load(void *opaque, int version_id)
diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index 48f918b71b..f34701b443 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -195,7 +195,7 @@ target_ulong helper_mret(CPURISCVState *env)
     uint64_t mstatus = env->mstatus;
     target_ulong prev_priv = get_field(mstatus, MSTATUS_MPP);
 
-    if (riscv_feature(env, RISCV_FEATURE_PMP) &&
+    if (riscv_cpu_cfg(env).pmp &&
         !pmp_get_num_rules(env) && (prev_priv != PRV_M)) {
         riscv_raise_exception(env, RISCV_EXCP_INST_ACCESS_FAULT, GETPC());
     }
diff --git a/target/riscv/pmp.c b/target/riscv/pmp.c
index bb54899635..1e7903dffa 100644
--- a/target/riscv/pmp.c
+++ b/target/riscv/pmp.c
@@ -265,7 +265,7 @@ static bool pmp_hart_has_privs_default(CPURISCVState *env, target_ulong addr,
         }
     }
 
-    if ((!riscv_feature(env, RISCV_FEATURE_PMP)) || (mode == PRV_M)) {
+    if (!riscv_cpu_cfg(env).pmp || (mode == PRV_M)) {
         /*
          * Privileged spec v1.10 states if HW doesn't implement any PMP entry
          * or no PMP entry matches an M-Mode access, the access succeeds.
-- 
2.39.1

[PATCH v5 7/9] hw/riscv/virt.c: do not use RISCV_FEATURE_MMU in create_fdt_socket_cpus()

[Daniel Henrique Barboza]

Read cpu_ptr->cfg.mmu directly. As a bonus, use cpu_ptr in
riscv_isa_string().

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>
---
 hw/riscv/virt.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index 86c4adc0c9..49f2c157f7 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -232,20 +232,21 @@ static void create_fdt_socket_cpus(RISCVVirtState *s, int socket,
     bool is_32_bit = riscv_is_32bit(&s->soc[0]);
 
     for (cpu = s->soc[socket].num_harts - 1; cpu >= 0; cpu--) {
+        RISCVCPU *cpu_ptr = &s->soc[socket].harts[cpu];
+
         cpu_phandle = (*phandle)++;
 
         cpu_name = g_strdup_printf("/cpus/cpu@%d",
             s->soc[socket].hartid_base + cpu);
         qemu_fdt_add_subnode(ms->fdt, cpu_name);
-        if (riscv_feature(&s->soc[socket].harts[cpu].env,
-                          RISCV_FEATURE_MMU)) {
+        if (cpu_ptr->cfg.mmu) {
             qemu_fdt_setprop_string(ms->fdt, cpu_name, "mmu-type",
                                     (is_32_bit) ? "riscv,sv32" : "riscv,sv48");
         } else {
             qemu_fdt_setprop_string(ms->fdt, cpu_name, "mmu-type",
                                     "riscv,none");
         }
-        name = riscv_isa_string(&s->soc[socket].harts[cpu]);
+        name = riscv_isa_string(cpu_ptr);
         qemu_fdt_setprop_string(ms->fdt, cpu_name, "riscv,isa", name);
         g_free(name);
         qemu_fdt_setprop_string(ms->fdt, cpu_name, "compatible", "riscv");
-- 
2.39.1

[PATCH v5 8/9] target/riscv: remove RISCV_FEATURE_MMU

[Daniel Henrique Barboza]

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 bd7ab5fceb..7ff4d90261 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 15d9542691..e76b206191 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 a8a7d0aa34..8c61171a0c 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..b7b8d0614f 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 1e7903dffa..c67de36942 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) {
             /*
              * If size is unknown (0), assume that all bytes
              * from addr to the end of the page will be accessed.
-- 
2.39.1

[PATCH v5 9/9] target/riscv/cpu: remove CPUArchState::features and friends

[Daniel Henrique Barboza]

The attribute is no longer used since we can retrieve all the enabled
features in the hart by using cpu->cfg instead.

Remove env->feature, riscv_feature() and riscv_set_feature(). We also
need to bump vmstate_riscv_cpu version_id and minimal_version_id since
'features' is no longer being migrated.

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.h     | 12 ------------
 target/riscv/machine.c |  5 ++---
 2 files changed, 2 insertions(+), 15 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 7ff4d90261..671734420b 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -173,8 +173,6 @@ struct CPUArchState {
     /* 128-bit helpers upper part return value */
     target_ulong retxh;
 
-    uint32_t features;
-
 #ifdef CONFIG_USER_ONLY
     uint32_t elf_flags;
 #endif
@@ -524,16 +522,6 @@ static inline int riscv_has_ext(CPURISCVState *env, target_ulong ext)
     return (env->misa_ext & ext) != 0;
 }
 
-static inline bool riscv_feature(CPURISCVState *env, int feature)
-{
-    return env->features & (1ULL << feature);
-}
-
-static inline void riscv_set_feature(CPURISCVState *env, int feature)
-{
-    env->features |= (1ULL << feature);
-}
-
 #include "cpu_user.h"
 
 extern const char * const riscv_int_regnames[];
diff --git a/target/riscv/machine.c b/target/riscv/machine.c
index 67e9e56853..9c455931d8 100644
--- a/target/riscv/machine.c
+++ b/target/riscv/machine.c
@@ -331,8 +331,8 @@ static const VMStateDescription vmstate_pmu_ctr_state = {
 
 const VMStateDescription vmstate_riscv_cpu = {
     .name = "cpu",
-    .version_id = 6,
-    .minimum_version_id = 6,
+    .version_id = 7,
+    .minimum_version_id = 7,
     .post_load = riscv_cpu_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINTTL_ARRAY(env.gpr, RISCVCPU, 32),
@@ -351,7 +351,6 @@ const VMStateDescription vmstate_riscv_cpu = {
         VMSTATE_UINT32(env.misa_ext, RISCVCPU),
         VMSTATE_UINT32(env.misa_mxl_max, RISCVCPU),
         VMSTATE_UINT32(env.misa_ext_mask, RISCVCPU),
-        VMSTATE_UINT32(env.features, RISCVCPU),
         VMSTATE_UINTTL(env.priv, RISCVCPU),
         VMSTATE_UINTTL(env.virt, RISCVCPU),
         VMSTATE_UINT64(env.resetvec, RISCVCPU),
-- 
2.39.1

Re: [PATCH v5 2/9] target/riscv: introduce riscv_cpu_cfg()

[Richard Henderson]

On 2/16/23 06:21, Daniel Henrique Barboza wrote:
> +static inline RISCVCPUConfig riscv_cpu_cfg(CPURISCVState *env)
> +{
> +    return env_archcpu(env)->cfg;
> +}

This structure is 144 bytes.  I don't think you want to be copying it around like that. 
Better to return a const pointer.


r~