From efb8b7e3e033df36d7e505f9d7b225e2a621abae Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Wed, 21 Dec 2011 16:38:10 +0100 Subject: [PATCH] kvm tool: Implement a serial FIFO emulation Adding FIFO functionality to the serial emulator to speed up the console handling. This also restricts sysrq functionality to the first serial port and fixes the sysrq injection, which was broken because nothing ever reset the BI status bit in the LSR. Signed-off-by: Thomas Gleixner Signed-off-by: Pekka Enberg --- tools/kvm/hw/serial.c | 161 ++++++++++++++++++++++++++++-------------- 1 file changed, 109 insertions(+), 52 deletions(-) diff --git a/tools/kvm/hw/serial.c b/tools/kvm/hw/serial.c index c0f69704c239..d1d67b0d5a2f 100644 --- a/tools/kvm/hw/serial.c +++ b/tools/kvm/hw/serial.c @@ -12,6 +12,15 @@ #include +/* + * This fakes a U6_16550A. The fifo len needs to be 64 as the kernel + * expects that for autodetection. + */ +#define FIFO_LEN 64 +#define FIFO_MASK (FIFO_LEN - 1) + +#define UART_IIR_TYPE_BITS 0xc0 + struct serial8250_device { pthread_mutex_t mutex; u8 id; @@ -20,8 +29,11 @@ struct serial8250_device { u8 irq; u8 irq_state; int txcnt; + int rxcnt; + int rxdone; + char txbuf[FIFO_LEN]; + char rxbuf[FIFO_LEN]; - u8 rbr; /* receive buffer */ u8 dll; u8 dlm; u8 iir; @@ -83,10 +95,34 @@ static struct serial8250_device devices[] = { }, }; +static void serial8250_flush_tx(struct serial8250_device *dev) +{ + dev->lsr |= UART_LSR_TEMT | UART_LSR_THRE; + + if (dev->txcnt) { + term_putc(CONSOLE_8250, dev->txbuf, dev->txcnt, dev->id); + dev->txcnt = 0; + } +} + static void serial8250_update_irq(struct kvm *kvm, struct serial8250_device *dev) { u8 iir = 0; + /* Handle clear rx */ + if (dev->lcr & UART_FCR_CLEAR_RCVR) { + dev->lcr &= ~UART_FCR_CLEAR_RCVR; + dev->rxcnt = dev->rxdone = 0; + dev->lsr &= ~UART_LSR_DR; + } + + /* Handle clear tx */ + if (dev->lcr & UART_FCR_CLEAR_XMIT) { + dev->lcr &= ~UART_FCR_CLEAR_XMIT; + dev->txcnt = 0; + dev->lsr |= UART_LSR_TEMT | UART_LSR_THRE; + } + /* Data ready and rcv interrupt enabled ? */ if ((dev->ier & UART_IER_RDI) && (dev->lsr & UART_LSR_DR)) iir |= UART_IIR_RDI; @@ -112,66 +148,57 @@ static void serial8250_update_irq(struct kvm *kvm, struct serial8250_device *dev * is nothing more to transmit, so we can reset our tx logic * here. */ - if (!(dev->ier & UART_IER_THRI)) { - dev->lsr |= UART_LSR_TEMT | UART_LSR_THRE; - dev->txcnt = 0; - } + if (!(dev->ier & UART_IER_THRI)) + serial8250_flush_tx(dev); } #define SYSRQ_PENDING_NONE 0 #define SYSRQ_PENDING_BREAK 1 -#define SYSRQ_PENDING_CMD 2 static int sysrq_pending; static void serial8250__sysrq(struct kvm *kvm, struct serial8250_device *dev) { - switch (sysrq_pending) { - case SYSRQ_PENDING_BREAK: - dev->lsr |= UART_LSR_DR | UART_LSR_BI; - - sysrq_pending = SYSRQ_PENDING_CMD; - break; - case SYSRQ_PENDING_CMD: - dev->rbr = 'p'; - dev->lsr |= UART_LSR_DR; - - sysrq_pending = SYSRQ_PENDING_NONE; - break; - } + dev->lsr |= UART_LSR_DR | UART_LSR_BI; + dev->rxbuf[dev->rxcnt++] = 'p'; + sysrq_pending = SYSRQ_PENDING_NONE; } -static void serial8250__receive(struct kvm *kvm, struct serial8250_device *dev) +static void serial8250__receive(struct kvm *kvm, struct serial8250_device *dev, + bool handle_sysrq) { int c; /* - * If the guest transmitted 16 chars in a row, we clear the + * If the guest transmitted a full fifo, we clear the * TEMT/THRE bits to let the kernel escape from the 8250 * interrupt handler. We come here only once a ms, so that - * should give the kernel the desired pause. + * should give the kernel the desired pause. That also flushes + * the tx fifo to the terminal. */ - dev->lsr |= UART_LSR_TEMT | UART_LSR_THRE; - dev->txcnt = 0; + serial8250_flush_tx(dev); - if (dev->lsr & UART_LSR_DR) + if (dev->mcr & UART_MCR_LOOP) return; - if (sysrq_pending) { - serial8250__sysrq(kvm, dev); + if ((dev->lsr & UART_LSR_DR) || dev->rxcnt) return; - } - if (!term_readable(CONSOLE_8250, dev->id)) + if (handle_sysrq && sysrq_pending) { + serial8250__sysrq(kvm, dev); return; + } - c = term_getc(CONSOLE_8250, dev->id); + while (term_readable(CONSOLE_8250, dev->id) && + dev->rxcnt < FIFO_LEN) { - if (c < 0) - return; + c = term_getc(CONSOLE_8250, dev->id); - dev->rbr = c; - dev->lsr |= UART_LSR_DR; + if (c < 0) + break; + dev->rxbuf[dev->rxcnt++] = c; + dev->lsr |= UART_LSR_DR; + } } void serial8250__update_consoles(struct kvm *kvm) @@ -183,7 +210,8 @@ void serial8250__update_consoles(struct kvm *kvm) mutex_lock(&dev->mutex); - serial8250__receive(kvm, dev); + /* Restrict sysrq injection to the first port */ + serial8250__receive(kvm, dev, i == 0); serial8250_update_irq(kvm, dev); @@ -209,11 +237,13 @@ static struct serial8250_device *find_device(u16 port) return NULL; } -static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, void *data, int size) +static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, + void *data, int size) { struct serial8250_device *dev; u16 offset; bool ret = true; + char *addr = data; dev = find_device(port); if (!dev) @@ -225,23 +255,33 @@ static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, voi switch (offset) { case UART_TX: - if (!(dev->lcr & UART_LCR_DLAB)) { - char *addr = data; - - if (!(dev->mcr & UART_MCR_LOOP)) - term_putc(CONSOLE_8250, addr, size, dev->id); - /* else FIXME: Inject data into rcv path for LOOP */ + if (dev->lcr & UART_LCR_DLAB) { + dev->dll = ioport__read8(data); + break; + } - if (++dev->txcnt == 16) - dev->lsr &= ~(UART_LSR_TEMT | UART_LSR_THRE); + /* Loopback mode */ + if (dev->mcr & UART_MCR_LOOP) { + if (dev->rxcnt < FIFO_LEN) { + dev->rxbuf[dev->rxcnt++] = *addr; + dev->lsr |= UART_LSR_DR; + } break; + } + + if (dev->txcnt < FIFO_LEN) { + dev->txbuf[dev->txcnt++] = *addr; + dev->lsr &= ~UART_LSR_TEMT; + if (dev->txcnt == FIFO_LEN / 2) + dev->lsr &= ~UART_LSR_THRE; } else { - dev->dll = ioport__read8(data); + /* Should never happpen */ + dev->lsr &= ~(UART_LSR_TEMT | UART_LSR_THRE); } break; case UART_IER: if (!(dev->lcr & UART_LCR_DLAB)) - dev->ier = ioport__read8(data) & 0x3f; + dev->ier = ioport__read8(data) & 0x0f; else dev->dlm = ioport__read8(data); break; @@ -275,6 +315,25 @@ static bool serial8250_out(struct ioport *ioport, struct kvm *kvm, u16 port, voi return ret; } +static void serial8250_rx(struct serial8250_device *dev, void *data) +{ + if (dev->rxdone == dev->rxcnt) + return; + + /* Break issued ? */ + if (dev->lsr & UART_LSR_BI) { + dev->lsr &= ~UART_LSR_BI; + ioport__write8(data, 0); + return; + } + + ioport__write8(data, dev->rxbuf[dev->rxdone++]); + if (dev->rxcnt == dev->rxdone) { + dev->lsr &= ~UART_LSR_DR; + dev->rxcnt = dev->rxdone = 0; + } +} + static bool serial8250_in(struct ioport *ioport, struct kvm *kvm, u16 port, void *data, int size) { struct serial8250_device *dev; @@ -291,12 +350,10 @@ static bool serial8250_in(struct ioport *ioport, struct kvm *kvm, u16 port, void switch (offset) { case UART_RX: - if (dev->lcr & UART_LCR_DLAB) { + if (dev->lcr & UART_LCR_DLAB) ioport__write8(data, dev->dll); - } else { - ioport__write8(data, dev->rbr); - dev->lsr &= ~UART_LSR_DR; - } + else + serial8250_rx(dev, data); break; case UART_IER: if (dev->lcr & UART_LCR_DLAB) @@ -305,7 +362,7 @@ static bool serial8250_in(struct ioport *ioport, struct kvm *kvm, u16 port, void ioport__write8(data, dev->ier); break; case UART_IIR: - ioport__write8(data, dev->iir); + ioport__write8(data, dev->iir | UART_IIR_TYPE_BITS); break; case UART_LCR: ioport__write8(data, dev->lcr); -- 2.39.5