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[2403:580b:97e8:0:82ce:f179:8a79:69f4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-718e58c68d3sm2528155b3a.84.2024.09.08.19.13.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Sep 2024 19:13:31 -0700 (PDT) From: Alistair Francis X-Google-Original-From: Alistair Francis To: alex.bennee@linaro.org, qemu-devel@nongnu.org, peter.maydell@linaro.org Cc: dbarboza@ventanamicro.com, palmer@dabbelt.com, zhiwei_liu@linux.alibaba.com, qemu-riscv@nongnu.org, Paolo Bonzini , alistair23@gmail.com, Bin Meng , liwei1518@gmail.com, Alistair Francis , =?utf-8?q?Marc-Andr=C3=A9_Lure?= =?utf-8?q?au?= , atishp@rivosinc.com, Alistair Francis , Thomas Huth Subject: [PATCH v3 1/2] hw/char: riscv_htif: Use blocking qemu_chr_fe_write_all Date: Mon, 9 Sep 2024 12:13:16 +1000 Message-ID: <20240909021317.58192-2-alistair.francis@wdc.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240909021317.58192-1-alistair.francis@wdc.com> References: <20240909021317.58192-1-alistair.francis@wdc.com> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::433; envelope-from=alistair23@gmail.com; helo=mail-pf1-x433.google.com X-Spam_score_int: -17 X-Spam_score: -1.8 X-Spam_bar: - X-Spam_report: (-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The current approach of using qemu_chr_fe_write() and ignoring the return values results in dropped characters [1]. Ideally we want to report FIFO status to the guest, but the HTIF isn't a real UART, so we don't really have a way to do that. Instead let's just use qemu_chr_fe_write_all() so at least we don't drop characters. 1: https://gitlab.com/qemu-project/qemu/-/issues/2114 Signed-off-by: Alistair Francis Reviewed-by: Daniel Henrique Barboza Reviewed-by: Thomas Huth --- hw/char/riscv_htif.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/hw/char/riscv_htif.c b/hw/char/riscv_htif.c index 9bef60def1..d40b542948 100644 --- a/hw/char/riscv_htif.c +++ b/hw/char/riscv_htif.c @@ -218,7 +218,11 @@ static void htif_handle_tohost_write(HTIFState *s, uint64_t val_written) tswap64(syscall[3]) == HTIF_CONSOLE_CMD_PUTC) { uint8_t ch; cpu_physical_memory_read(tswap64(syscall[2]), &ch, 1); - qemu_chr_fe_write(&s->chr, &ch, 1); + /* + * XXX this blocks entire thread. Rewrite to use + * qemu_chr_fe_write and background I/O callbacks + */ + qemu_chr_fe_write_all(&s->chr, &ch, 1); resp = 0x100 | (uint8_t)payload; } else { qemu_log_mask(LOG_UNIMP, @@ -237,7 +241,11 @@ static void htif_handle_tohost_write(HTIFState *s, uint64_t val_written) return; } else if (cmd == HTIF_CONSOLE_CMD_PUTC) { uint8_t ch = (uint8_t)payload; - qemu_chr_fe_write(&s->chr, &ch, 1); + /* + * XXX this blocks entire thread. Rewrite to use + * qemu_chr_fe_write and background I/O callbacks + */ + qemu_chr_fe_write_all(&s->chr, &ch, 1); resp = 0x100 | (uint8_t)payload; } else { qemu_log("HTIF device %d: unknown command\n", device);