[PATCH for-8.1 v3 26/26] target/riscv: allow write_misa() to enable RVV

[Daniel Henrique Barboza]

Allow write_misa() to enable RVV like we did with RVG. We'll need a
riscv_cpu_enable_v() to enable all related misa bits and Z extensions.
This new helper validates the existing 'env' conf by using the existing
riscv_cpu_validate_v(). We'll also check if we'll be able to enable 'F'
by checking for ext_zfinx.

As with RVG, enabling RVV is considered to be a standalone operation in
write_misa(). This means that we'll guarantee that we're not being
inconsistent in riscv_cpu_enable_v() and that we're okay with skipping
regular validation.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
---
 target/riscv/cpu.c | 35 +++++++++++++++++++++++++++++++++++
 target/riscv/cpu.h |  1 +
 target/riscv/csr.c | 14 ++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 73a5fa46ee..9c16b29f27 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -983,6 +983,41 @@ static void riscv_cpu_validate_v(CPURISCVState *env,
     env->vext_ver = vext_version;
 }
 
+target_ulong riscv_cpu_enable_v(RISCVCPU *cpu, Error **errp)
+{
+    CPURISCVState *env = &cpu->env;
+    RISCVCPUConfig *cfg = &cpu->cfg;
+    Error *local_err = NULL;
+
+    riscv_cpu_validate_v(env, cfg, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return 0;
+    }
+
+    if (cpu->cfg.ext_zfinx) {
+        error_setg(errp, "Unable to enable V: Zfinx is enabled, "
+                         "so F can not be enabled");
+        return 0;
+    }
+
+    cfg->ext_f = true;
+    env->misa_ext |= RVF;
+
+    cfg->ext_d = true;
+    env->misa_ext |= RVD;
+
+    /*
+     * The V vector extension depends on the
+     *  Zve32f, Zve64f and Zve64d extensions.
+     */
+    cpu->cfg.ext_zve64d = true;
+    cpu->cfg.ext_zve64f = true;
+    cpu->cfg.ext_zve32f = true;
+
+    return env->misa_ext;
+}
+
 static void riscv_cpu_validate_priv_spec(RISCVCPU *cpu, Error **errp)
 {
     CPURISCVState *env = &cpu->env;
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 3ca1d4903c..45e801d926 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -600,6 +600,7 @@ void riscv_cpu_validate_extensions(RISCVCPU *cpu, uint32_t 
misa_ext,
 void riscv_cpu_commit_cpu_cfg(RISCVCPU *cpu, uint32_t misa_ext);
 
 target_ulong riscv_cpu_enable_g(RISCVCPU *cpu, Error **errp);
+target_ulong riscv_cpu_enable_v(RISCVCPU *cpu, Error **errp);
 
 #define cpu_list riscv_cpu_list
 #define cpu_mmu_index riscv_cpu_mmu_index
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 4335398c19..e9e1afc57e 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -1395,6 +1395,20 @@ static RISCVException write_misa(CPURISCVState *env, int 
csrno,
         goto commit;
     }
 
+    if (val & RVV && !(env->misa_ext & RVV)) {
+        /*
+         * If the write wants to enable RVV, only RVV and
+         * its dependencies will be updated in the CSR.
+         */
+        val = riscv_cpu_enable_v(cpu, &local_err);
+        if (local_err != NULL) {
+            return RISCV_EXCP_NONE;
+        }
+
+        val |= RVV;
+        goto commit;
+    }
+
     /*
      * This flow is similar to what riscv_cpu_realize() does,
      * with the difference that we will update env->misa_ext
-- 
2.39.2