Re: [Qemu-devel] [PATCH] Fix serial interface vmstate

[Juan Quintela <quintela@redhat.com>]

"Pavel Dovgaluk" <Pavel.Dovgaluk@ispras.ru> wrote:
>   This patch fixes save/restore of serial interface's state.
>   It includes changing of fcr setter function (it now does not invoke
> an interrupt while loading vmstate), and saving/restoring all
> fields that describe the state of serial interface (including timers).
>
> Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@gmail.com>

I think we can do this with a new subsection.

> ---
>  hw/serial.c |  133 ++++++++++++++++++++++++++++++++++++++--------------------
>  1 files changed, 87 insertions(+), 46 deletions(-)
>
> diff --git a/hw/serial.c b/hw/serial.c
> index 0ee61dd..936e048 100644
> --- a/hw/serial.c
> +++ b/hw/serial.c
> @@ -362,6 +362,62 @@ static void serial_xmit(void *opaque)
>  }
>  
>  
> +/* Setter for FCR.
> +   is_load flag means, that value is set while loading VM state
> +   and interrupt should not be invoked */
> +static void serial_write_fcr(void *opaque, uint32_t val, int is_load)
> +{
> +    SerialState *s = opaque;
> +
> +    val = val & 0xFF;
> +
> +    if (s->fcr == val)
> +        return;

This looks like a test.  if this is true, we don't need to restore the
other values, so we shouldbe safe, right?


> +    /* Did the enable/disable flag change? If so, make sure FIFOs get flushed */
> +    if ((val ^ s->fcr) & UART_FCR_FE)
> +        val |= UART_FCR_XFR | UART_FCR_RFR;
> +
> +    /* FIFO clear */
> +
> +    if (val & UART_FCR_RFR) {
> +        qemu_del_timer(s->fifo_timeout_timer);
> +        s->timeout_ipending=0;
> +        fifo_clear(s,RECV_FIFO);
> +    }
> +
> +    if (val & UART_FCR_XFR) {
> +        fifo_clear(s,XMIT_FIFO);
> +    }
> +
> +    if (val & UART_FCR_FE) {
> +        s->iir |= UART_IIR_FE;
> +        /* Set RECV_FIFO trigger Level */
> +        switch (val & 0xC0) {
> +        case UART_FCR_ITL_1:
> +            s->recv_fifo.itl = 1;
> +            break;
> +        case UART_FCR_ITL_2:
> +            s->recv_fifo.itl = 4;
> +            break;
> +        case UART_FCR_ITL_3:
> +            s->recv_fifo.itl = 8;
> +            break;
> +        case UART_FCR_ITL_4:
> +            s->recv_fifo.itl = 14;
> +            break;
> +        }
> +    } else
> +        s->iir &= ~UART_IIR_FE;
> +
> +    /* Set fcr - or at least the bits in it that are supposed to "stick" */
> +    s->fcr = val & 0xC9;
> +    if (!is_load) {
> +        serial_update_irq(s);
> +    }

we can put the serial_update_irq() at caller site.  Function is only
called twice, on place need to call serial_update_irq() and the other not.


> +}
> +
> +
>  static void serial_ioport_write(void *opaque, uint32_t addr, uint32_t val)
>  {
>      SerialState *s = opaque;
> @@ -414,50 +470,7 @@ static void serial_ioport_write(void *opaque, uint32_t addr, uint32_t val)
>          }
>          break;
>      case 2:
> -        val = val & 0xFF;
> -
> -        if (s->fcr == val)
> -            break;
> -
> -        /* Did the enable/disable flag change? If so, make sure FIFOs get flushed */
> -        if ((val ^ s->fcr) & UART_FCR_FE)
> -            val |= UART_FCR_XFR | UART_FCR_RFR;
> -
> -        /* FIFO clear */
> -
> -        if (val & UART_FCR_RFR) {
> -            qemu_del_timer(s->fifo_timeout_timer);
> -            s->timeout_ipending=0;
> -            fifo_clear(s,RECV_FIFO);
> -        }
> -
> -        if (val & UART_FCR_XFR) {
> -            fifo_clear(s,XMIT_FIFO);
> -        }
> -
> -        if (val & UART_FCR_FE) {
> -            s->iir |= UART_IIR_FE;
> -            /* Set RECV_FIFO trigger Level */
> -            switch (val & 0xC0) {
> -            case UART_FCR_ITL_1:
> -                s->recv_fifo.itl = 1;
> -                break;
> -            case UART_FCR_ITL_2:
> -                s->recv_fifo.itl = 4;
> -                break;
> -            case UART_FCR_ITL_3:
> -                s->recv_fifo.itl = 8;
> -                break;
> -            case UART_FCR_ITL_4:
> -                s->recv_fifo.itl = 14;
> -                break;
> -            }
> -        } else
> -            s->iir &= ~UART_IIR_FE;
> -
> -        /* Set fcr - or at least the bits in it that are supposed to "stick" */
> -        s->fcr = val & 0xC9;
> -        serial_update_irq(s);
> +        serial_write_fcr(s, val, 0);
>          break;
>      case 3:
>          {
> @@ -673,20 +686,38 @@ static int serial_post_load(void *opaque, int version_id)
>          s->fcr_vmstate = 0;
>      }
>      /* Initialize fcr via setter to perform essential side-effects */
> -    serial_ioport_write(s, 0x02, s->fcr_vmstate);
> +    serial_write_fcr(s, s->fcr_vmstate, 1);
>      serial_update_parameters(s);
>      return 0;
>  }
>  
> +
> +static const VMStateDescription vmstate_fifo = {
> +    .name = "serial FIFO",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields      = (VMStateField []) {
> +        VMSTATE_BUFFER(data, SerialFIFO),
> +        VMSTATE_UINT8(count, SerialFIFO),
> +        VMSTATE_UINT8(itl, SerialFIFO),
> +        VMSTATE_UINT8(tail, SerialFIFO),
> +        VMSTATE_UINT8(head, SerialFIFO),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +
>  static const VMStateDescription vmstate_serial = {
>      .name = "serial",
> -    .version_id = 3,
> +    .version_id = 4,
>      .minimum_version_id = 2,
>      .pre_save = serial_pre_save,
>      .post_load = serial_post_load,
>      .fields      = (VMStateField []) {
>          VMSTATE_UINT16_V(divider, SerialState, 2),
>          VMSTATE_UINT8(rbr, SerialState),
> +        VMSTATE_UINT8_V(thr, SerialState, 4),
> +        VMSTATE_UINT8_V(tsr, SerialState, 4),
>          VMSTATE_UINT8(ier, SerialState),
>          VMSTATE_UINT8(iir, SerialState),
>          VMSTATE_UINT8(lcr, SerialState),
> @@ -695,6 +726,16 @@ static const VMStateDescription vmstate_serial = {
>          VMSTATE_UINT8(msr, SerialState),
>          VMSTATE_UINT8(scr, SerialState),
>          VMSTATE_UINT8_V(fcr_vmstate, SerialState, 3),
> +        VMSTATE_INT32_V(thr_ipending, SerialState, 4),
> +        VMSTATE_INT32_V(last_break_enable, SerialState, 4),
> +        VMSTATE_INT32_V(tsr_retry, SerialState, 4),
> +        VMSTATE_STRUCT(recv_fifo, SerialState, 4, vmstate_fifo, SerialFIFO),
> +        VMSTATE_STRUCT(xmit_fifo, SerialState, 4, vmstate_fifo, SerialFIFO),
> +        VMSTATE_TIMER_V(fifo_timeout_timer, SerialState, 4),
> +        VMSTATE_INT32_V(timeout_ipending, SerialState, 4),
> +        VMSTATE_TIMER_V(transmit_timer, SerialState, 4),
> +        VMSTATE_INT32_V(poll_msl, SerialState, 4),
> +        VMSTATE_TIMER_V(modem_status_poll, SerialState, 4),
>          VMSTATE_END_OF_LIST()
>      }
>  };

Anyways, I think that it is better to split the change in two patches.
One that refactor the common code in another function.  And the other
that adds the VMSTATE bits, I can add the subsection part if you want.

Later, Juan.