[RFC PATCH v4 1/2] target/riscv: Add RISC-V CSR qtest support

[Ivan Klokov]

The RISC-V architecture supports the creation of custom
CSR-mapped devices. It would be convenient to test them in the same way
as MMIO-mapped devices. To do this, a new call has been added
to read/write CSR registers.

Signed-off-by: Ivan Klokov <ivan.klokov@syntacore.com>
---
 target/riscv/cpu.c     | 17 ++++++++++++++
 target/riscv/cpu.h     |  3 +++
 target/riscv/csr.c     | 53 +++++++++++++++++++++++++++++++++++++++++-
 tests/qtest/libqtest.c | 27 +++++++++++++++++++++
 tests/qtest/libqtest.h | 14 +++++++++++
 5 files changed, 113 insertions(+), 1 deletion(-)

diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
index 69a08e8c2c..7c15860414 100644
--- a/target/riscv/cpu.c
+++ b/target/riscv/cpu.c
@@ -1149,6 +1149,18 @@ void riscv_cpu_finalize_features(RISCVCPU *cpu, Error 
**errp)
     }
 }
 
+#ifndef CONFIG_USER_ONLY
+static void riscv_cpu_register_csr_qtest_callback(void)
+{
+    static gsize reinit_done;
+    if (g_once_init_enter(&reinit_done)) {
+        qtest_set_command_cb(csr_qtest_callback);
+
+        g_once_init_leave(&reinit_done, 1);
+    }
+}
+#endif
+
 static void riscv_cpu_realize(DeviceState *dev, Error **errp)
 {
     CPUState *cs = CPU(dev);
@@ -1175,6 +1187,11 @@ static void riscv_cpu_realize(DeviceState *dev, Error 
**errp)
 
     riscv_cpu_register_gdb_regs_for_features(cs);
 
+#ifndef CONFIG_USER_ONLY
+    /* register callback for csr qtests */
+    riscv_cpu_register_csr_qtest_callback();
+#endif
+
 #ifndef CONFIG_USER_ONLY
     if (cpu->cfg.debug) {
         riscv_trigger_realize(&cpu->env);
diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index 6fe0d712b4..6d4bbec53c 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -32,6 +32,8 @@
 #include "cpu_cfg.h"
 #include "qapi/qapi-types-common.h"
 #include "cpu-qom.h"
+#include "qemu/cutils.h"
+#include "sysemu/qtest.h"
 
 typedef struct CPUArchState CPURISCVState;
 
@@ -813,6 +815,7 @@ bool riscv_cpu_accelerator_compatible(RISCVCPU *cpu);
 
 /* CSR function table */
 extern riscv_csr_operations csr_ops[CSR_TABLE_SIZE];
+bool csr_qtest_callback(CharBackend *chr, gchar **words);
 
 extern const bool valid_vm_1_10_32[], valid_vm_1_10_64[];
 
diff --git a/target/riscv/csr.c b/target/riscv/csr.c
index 58ef7079dc..f4f5128c9c 100644
--- a/target/riscv/csr.c
+++ b/target/riscv/csr.c
@@ -29,7 +29,7 @@
 #include "sysemu/cpu-timers.h"
 #include "qemu/guest-random.h"
 #include "qapi/error.h"
-
+#include "tests/qtest/libqtest.h"
 
 /* CSR function table public API */
 void riscv_get_csr_ops(int csrno, riscv_csr_operations *ops)
@@ -4549,6 +4549,57 @@ static RISCVException write_jvt(CPURISCVState *env, int 
csrno,
     return RISCV_EXCP_NONE;
 }
 
+#if !defined(CONFIG_USER_ONLY)
+static uint64_t csr_call(char *cmd, uint64_t cpu_num, int csrno,
+                                uint64_t *val)
+{
+    RISCVCPU *cpu = RISCV_CPU(cpu_by_arch_id(cpu_num));
+    CPURISCVState *env = &cpu->env;
+
+    int ret = RISCV_EXCP_NONE;
+    if (strcmp(cmd, "get_csr") == 0) {
+        ret = riscv_csrrw(env, csrno, (target_ulong *)val, 0, 0);
+
+    } else if (strcmp(cmd, "set_csr") == 0) {
+        ret = riscv_csrrw(env, csrno, NULL, *(target_ulong *)val, 
MAKE_64BIT_MASK(0, TARGET_LONG_BITS));
+    }
+
+    if (ret == RISCV_EXCP_NONE) {
+        ret = 0;
+    } else {
+        g_assert_not_reached();
+    }
+
+    return ret;
+}
+
+bool csr_qtest_callback(CharBackend *chr, gchar **words)
+{
+    if (strcmp(words[0], "csr") == 0) {
+
+        uint64_t res, cpu;
+
+        uint64_t val;
+        int rc, csr;
+
+        rc = qemu_strtou64(words[2], NULL, 0, &cpu);
+        g_assert(rc == 0);
+        rc = qemu_strtoi(words[3], NULL, 0, &csr);
+        g_assert(rc == 0);
+        rc = qemu_strtou64(words[4], NULL, 0, &val);
+        g_assert(rc == 0);
+        res = csr_call(words[1], cpu, csr, &val);
+
+        qtest_send_prefix(chr);
+        qtest_sendf(chr, "OK %"PRIx64" "TARGET_FMT_lx"\n", res, 
(target_ulong)val);
+
+        return true;
+    }
+
+    return false;
+}
+#endif
+
 /*
  * Control and Status Register function table
  * riscv_csr_operations::predicate() must be provided for an implemented CSR
diff --git a/tests/qtest/libqtest.c b/tests/qtest/libqtest.c
index c7f6897d78..f8c3ff15a9 100644
--- a/tests/qtest/libqtest.c
+++ b/tests/qtest/libqtest.c
@@ -1205,6 +1205,33 @@ uint64_t qtest_rtas_call(QTestState *s, const char *name,
     return 0;
 }
 
+static void qtest_rsp_csr(QTestState *s, uint64_t *val)
+{
+    gchar **args;
+    uint64_t ret;
+    int rc;
+
+    args = qtest_rsp_args(s, 3);
+
+    rc = qemu_strtou64(args[1], NULL, 16, &ret);
+    g_assert(rc == 0);
+    rc = qemu_strtou64(args[2], NULL, 16, val);
+    g_assert(rc == 0);
+
+    g_strfreev(args);
+}
+
+uint64_t qtest_csr_call(QTestState *s, const char *name,
+                         uint64_t cpu, int csr,
+                         uint64_t *val)
+{
+    qtest_sendf(s, "csr %s 0x%"PRIx64" %d 0x%"PRIx64"\n",
+                    name, cpu, csr, *val);
+
+    qtest_rsp_csr(s, val);
+    return 0;
+}
+
 void qtest_add_func(const char *str, void (*fn)(void))
 {
     gchar *path = g_strdup_printf("/%s/%s", qtest_get_arch(), str);
diff --git a/tests/qtest/libqtest.h b/tests/qtest/libqtest.h
index c261b7e0b3..7b547e5e2c 100644
--- a/tests/qtest/libqtest.h
+++ b/tests/qtest/libqtest.h
@@ -577,6 +577,20 @@ uint64_t qtest_rtas_call(QTestState *s, const char *name,
                          uint32_t nargs, uint64_t args,
                          uint32_t nret, uint64_t ret);
 
+/**
+ * qtest_csr_call:
+ * @s: #QTestState instance to operate on.
+ * @name: name of the command to call.
+ * @cpu: hart number.
+ * @csr: CSR number.
+ * @val: Value for reading/writing.
+ *
+ * Call an RISC-V CSR read/write function
+ */
+uint64_t qtest_csr_call(QTestState *s, const char *name,
+                         uint64_t cpu, int csr,
+                         unsigned long *val);
+
 /**
  * qtest_bufread:
  * @s: #QTestState instance to operate on.
-- 
2.34.1