[PATCH v4] target/riscv/kvm/kvm-cpu.c: kvm_riscv_handle_sbi() fail with vendor-specific SBI

[Alexei Filippov <alexei.filippov@syntacore.com>]

kvm_riscv_handle_sbi() may return not supported return code to not trigger
qemu abort with vendor-specific sbi.

Added SBI related return code's defines.

Signed-off-by: Alexei Filippov <alexei.filippov@syntacore.com>
Fixes: 4eb47125 ("target/riscv: Handle KVM_EXIT_RISCV_SBI exit")
---

Changes since v3:
        -Clear Reviewed-by tags
 target/riscv/kvm/kvm-cpu.c         | 13 +++++--------
 target/riscv/sbi_ecall_interface.h | 12 ++++++++++++
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 6a6c6cae80..844942d9ba 100644
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1392,7 +1392,6 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cs)
 
 static int kvm_riscv_handle_sbi(CPUState *cs, struct kvm_run *run)
 {
-    int ret = 0;
     unsigned char ch;
     switch (run->riscv_sbi.extension_id) {
     case SBI_EXT_0_1_CONSOLE_PUTCHAR:
@@ -1400,22 +1399,20 @@ static int kvm_riscv_handle_sbi(CPUState *cs, struct kvm_run *run)
         qemu_chr_fe_write(serial_hd(0)->be, &ch, sizeof(ch));
         break;
     case SBI_EXT_0_1_CONSOLE_GETCHAR:
-        ret = qemu_chr_fe_read_all(serial_hd(0)->be, &ch, sizeof(ch));
-        if (ret == sizeof(ch)) {
+        if (qemu_chr_fe_read_all(serial_hd(0)->be, &ch, sizeof(ch)) == sizeof(ch)) {
             run->riscv_sbi.ret[0] = ch;
         } else {
-            run->riscv_sbi.ret[0] = -1;
+            run->riscv_sbi.ret[0] = SBI_ERR_FAILURE;
         }
-        ret = 0;
         break;
     default:
         qemu_log_mask(LOG_UNIMP,
-                      "%s: un-handled SBI EXIT, specific reasons is %lu\n",
+                      "%s: Unhandled SBI exit with extension-id %lu\n",
                       __func__, run->riscv_sbi.extension_id);
-        ret = -1;
+        run->riscv_sbi.ret[0] = SBI_ERR_NOT_SUPPORTED;
         break;
     }
-    return ret;
+    return 0;
 }
 
 int kvm_arch_handle_exit(CPUState *cs, struct kvm_run *run)
diff --git a/target/riscv/sbi_ecall_interface.h b/target/riscv/sbi_ecall_interface.h
index 43899d08f6..a2e21d9b8c 100644
--- a/target/riscv/sbi_ecall_interface.h
+++ b/target/riscv/sbi_ecall_interface.h
@@ -69,4 +69,16 @@
 #define SBI_EXT_VENDOR_END              0x09FFFFFF
 /* clang-format on */
 
+/* SBI return error codes */
+#define SBI_SUCCESS                  0
+#define SBI_ERR_FAILURE             -1
+#define SBI_ERR_NOT_SUPPORTED       -2
+#define SBI_ERR_INVALID_PARAM       -3
+#define SBI_ERR_DENIED              -4
+#define SBI_ERR_INVALID_ADDRESS     -5
+#define SBI_ERR_ALREADY_AVAILABLE   -6
+#define SBI_ERR_ALREADY_STARTED     -7
+#define SBI_ERR_ALREADY_STOPPED     -8
+#define SBI_ERR_NO_SHMEM            -9
+
 #endif
-- 
2.34.1