target/riscv/tcg: add tcg_cpu_finalize_features()

The query-cpu-model-expansion API is capable of passing extra properties
to a given CPU model and tell callers if this custom configuration is
valid.

The RISC-V version of the API is not quite there yet. The reason is the
realize() flow in the TCG driver, where most of the validation is done
in tcg_cpu_realizefn(). riscv_cpu_finalize_features() is then used to
validate satp_mode for both TCG and KVM CPUs.

Our ARM friends uses a concept of 'finalize_features()', a step done in
the end of realize() where the CPU features are validated. We have a
riscv_cpu_finalize_features() helper that, at this moment, is only
validating satp_mode.

Re-use this existing helper to do all CPU extension validation we
required after at the end of realize(). Make it public to allow APIs to
use it. At this moment only the TCG driver requires a realize() time
validation, thus, to avoid adding accelerator specific helpers in the
API, riscv_cpu_finalize_features() uses
riscv_tcg_cpu_finalize_features() if we are running TCG. The API will
then use riscv_cpu_finalize_features() regardless of the current
accelerator.

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-ID: <20231018195638.211151-4-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

target/riscv/cpu.c

@@ -34,6 +34,7 @@
 #include "sysemu/kvm.h"
 #include "sysemu/tcg.h"
 #include "kvm/kvm_riscv.h"
+#include "tcg/tcg-cpu.h"
 #include "tcg/tcg.h"
 
 /* RISC-V CPU definitions */
@@ -998,11 +999,24 @@ static void riscv_cpu_satp_mode_finalize(RISCVCPU *cpu, Error **errp)
 }
 #endif
 
-static void riscv_cpu_finalize_features(RISCVCPU *cpu, Error **errp)
+void riscv_cpu_finalize_features(RISCVCPU *cpu, Error **errp)
 {
-#ifndef CONFIG_USER_ONLY
     Error *local_err = NULL;
 
+    /*
+     * KVM accel does not have a specialized finalize()
+     * callback because its extensions are validated
+     * in the get()/set() callbacks of each property.
+     */
+    if (tcg_enabled()) {
+        riscv_tcg_cpu_finalize_features(cpu, &local_err);
+        if (local_err != NULL) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+
+#ifndef CONFIG_USER_ONLY
     riscv_cpu_satp_mode_finalize(cpu, &local_err);
     if (local_err != NULL) {
         error_propagate(errp, local_err);

target/riscv/cpu.h

@@ -756,6 +756,7 @@ typedef struct isa_ext_data {
 extern const RISCVIsaExtData isa_edata_arr[];
 char *riscv_cpu_get_name(RISCVCPU *cpu);
 
+void riscv_cpu_finalize_features(RISCVCPU *cpu, Error **errp);
 void riscv_add_satp_mode_properties(Object *obj);
 
 /* CSR function table */

target/riscv/tcg/tcg-cpu.c

@@ -548,6 +548,39 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp)
     riscv_cpu_disable_priv_spec_isa_exts(cpu);
 }
 
+void riscv_tcg_cpu_finalize_features(RISCVCPU *cpu, Error **errp)
+{
+    CPURISCVState *env = &cpu->env;
+    Error *local_err = NULL;
+
+    riscv_cpu_validate_priv_spec(cpu, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    riscv_cpu_validate_misa_priv(env, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    if (cpu->cfg.epmp && !cpu->cfg.pmp) {
+        /*
+         * Enhanced PMP should only be available
+         * on harts with PMP support
+         */
+        error_setg(errp, "Invalid configuration: EPMP requires PMP support");
+        return;
+    }
+
+    riscv_cpu_validate_set_extensions(cpu, &local_err);
+    if (local_err != NULL) {
+        error_propagate(errp, local_err);
+        return;
+    }
+}
+
 static bool riscv_cpu_is_generic(Object *cpu_obj)
 {
     return object_dynamic_cast(cpu_obj, TYPE_RISCV_DYNAMIC_CPU) != NULL;
@@ -563,7 +596,6 @@ static bool riscv_cpu_is_generic(Object *cpu_obj)
 static bool tcg_cpu_realize(CPUState *cs, Error **errp)
 {
     RISCVCPU *cpu = RISCV_CPU(cs);
-    CPURISCVState *env = &cpu->env;
     Error *local_err = NULL;
 
     if (object_dynamic_cast(OBJECT(cpu), TYPE_RISCV_CPU_HOST)) {
@@ -579,34 +611,9 @@ static bool tcg_cpu_realize(CPUState *cs, Error **errp)
         return false;
     }
 
-    riscv_cpu_validate_priv_spec(cpu, &local_err);
-    if (local_err != NULL) {
-        error_propagate(errp, local_err);
-        return false;
-    }
-
-    riscv_cpu_validate_misa_priv(env, &local_err);
-    if (local_err != NULL) {
-        error_propagate(errp, local_err);
-        return false;
-    }
-
-    if (cpu->cfg.epmp && !cpu->cfg.pmp) {
-        /*
-         * Enhanced PMP should only be available
-         * on harts with PMP support
-         */
-        error_setg(errp, "Invalid configuration: EPMP requires PMP support");
-        return false;
-    }
-
-    riscv_cpu_validate_set_extensions(cpu, &local_err);
-    if (local_err != NULL) {
-        error_propagate(errp, local_err);
-        return false;
-    }
-
 #ifndef CONFIG_USER_ONLY
+    CPURISCVState *env = &cpu->env;
+
     CPU(cs)->tcg_cflags |= CF_PCREL;
 
     if (cpu->cfg.ext_sstc) {

target/riscv/tcg/tcg-cpu.h

@@ -23,5 +23,6 @@
 #include "cpu.h"
 
 void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, Error **errp);
+void riscv_tcg_cpu_finalize_features(RISCVCPU *cpu, Error **errp);
 
 #endif