target/riscv: use qemu_chr_fe_write_all() in DBCN_CONSOLE_WRITE_BYTE

The SBI spec states, for console write byte:

"This is a blocking SBI call and it will only return after writing the
specified byte to the debug console. It will also return, with
SBI_ERR_FAILED, if there are I/O errors."

Being a blocker call will either succeed writing the byte or error out,
it's feasible to use the blocking qemu_chr_fe_write_all() instead of
qemu_chr_fe_write().

Last but not the least, we will duck possible changes in
qemu_chr_fe_write() where ret = 0 will have a 'zero byte written'
semantic [1] - something that we're not ready to deal in this current
state.

[1] https://lore.kernel.org/qemu-devel/CAFEAcA_kEndvNtw4EHySXWwQPoGs029yAzZGGBcV=zGHaj7KUQ@mail.gmail.com/

Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-ID: <20250605094456.1385105-2-dbarboza@ventanamicro.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

diff --git a/target/riscv/kvm/kvm-cpu.c b/target/riscv/kvm/kvm-cpu.c
index 502d33f404c461c7e701c0e740e6bde82b2a96f2..5c19062c19b6044e4dc6212ed981d45d7ab539dd 100644 (file)
--- a/target/riscv/kvm/kvm-cpu.c
+++ b/target/riscv/kvm/kvm-cpu.c
@@ -1619,7 +1619,7 @@ static void kvm_riscv_handle_sbi_dbcn(CPUState *cs, struct kvm_run *run)
         break;
     case SBI_EXT_DBCN_CONSOLE_WRITE_BYTE:
         ch = run->riscv_sbi.args[0];
-        ret = qemu_chr_fe_write(serial_hd(0)->be, &ch, sizeof(ch));
+        ret = qemu_chr_fe_write_all(serial_hd(0)->be, &ch, sizeof(ch));
 
         if (ret < 0) {
             error_report("SBI_EXT_DBCN_CONSOLE_WRITE_BYTE: error when "