Re: [Qemu-devel] [PATCH v3] ps2: set ps/2 output buffer size as the same as kernel

[Amos Kong]

On Thu, Apr 24, 2014 at 08:06:19PM +0800, address@hidden wrote:
> From: Gonglei <address@hidden>
> 
> According to the PS/2 Mouse/Keyboard Protocol, the keyboard outupt buffer size
> is 16 bytes. And the PS2_QUEUE_SIZE 256 was introduced in Qemu from the very
> beginning.
> 
> When I started a  redhat5.6 32bit guest, meanwhile tapped the keyboard as 
> quickly as
> possible, the screen would show me "i8042.c: No controller found". As a 
> result,
> I couldn't use the keyboard in the VNC client.
> 
> Previous discussion about the issue in maillist:
> http://thread.gmane.org/gmane.comp.emulators.qemu/43294/focus=47180
> 
> This patch has been tested on redhat5.6 32-bit/suse11sp3 64-bit guests.
> More easy meathod to reproduce:
> 1.boot a guest with libvirt.
> 2.connect to VNC client.
> 3.as you see the BIOS, bootloader, Linux booting, run the follow simply shell 
> script:
> for((i=0;i<10000000;i++)) do virsh send-key redhat5.6 KEY_A; done

Why we can't break keyboard by flooding input after boot up?
 
> Actual results:
> dmesg show "i8042.c: No controller found." And the keyboard is out of work.
> 
> Signed-off-by: Gonglei <address@hidden>
> ---
> v2: rework by Gerd Hoffmann's suggestion:
>  - adjust the code style
>  - adjust the ps/2 mouse queue buffer judging condition
>  - add pre_save() for ps/2 keyboard and mouse
> v3:
>  - change the check enough buffer for ps2_mouse_send_packet() call
>    as suggested by Gerd Hoffmann.
> 
>  hw/input/ps2.c |   74 +++++++++++++++++++++++++++++++++++++++++++++++++++----
>  1 files changed, 68 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/input/ps2.c b/hw/input/ps2.c
> index 3412079..b7835c2 100644
> --- a/hw/input/ps2.c
> +++ b/hw/input/ps2.c
> @@ -71,10 +71,12 @@
>  #define MOUSE_STATUS_ENABLED    0x20
>  #define MOUSE_STATUS_SCALE21    0x10
>  
> -#define PS2_QUEUE_SIZE 256
> +#define PS2_QUEUE_SIZE 16  /* Buffer size required by PS/2 protocol */
>  
>  typedef struct {
> -    uint8_t data[PS2_QUEUE_SIZE];
> +    /* Keep the data array 256 bytes long, which compatibility
> +     with older qemu versions. */
> +    uint8_t data[256];
>      int rptr, wptr, count;
>  } PS2Queue;
>  
> @@ -137,7 +139,7 @@ void ps2_queue(void *opaque, int b)
>      PS2State *s = (PS2State *)opaque;
>      PS2Queue *q = &s->queue;
>  
> -    if (q->count >= PS2_QUEUE_SIZE)
> +    if (q->count >= PS2_QUEUE_SIZE - 1)
>          return;
>      q->data[q->wptr] = b;
>      if (++q->wptr == PS2_QUEUE_SIZE)
> @@ -374,9 +376,8 @@ static void ps2_mouse_event(void *opaque,
>          qemu_system_wakeup_request(QEMU_WAKEUP_REASON_OTHER);
>      }
>  
> -    if (!(s->mouse_status & MOUSE_STATUS_REMOTE) &&
> -        (s->common.queue.count < (PS2_QUEUE_SIZE - 16))) {
> -        for(;;) {
> +    if (!(s->mouse_status & MOUSE_STATUS_REMOTE)) {
> +        while (s->common.queue.count < PS2_QUEUE_SIZE - 4) {
>              /* if not remote, send event. Multiple events are sent if
>                 too big deltas */
>              ps2_mouse_send_packet(s);
> @@ -528,6 +529,34 @@ static void ps2_common_reset(PS2State *s)
>      s->update_irq(s->update_arg, 0);
>  }
>  
> +static void ps2_common_post_load(PS2State *s)
> +{
> +    PS2Queue *q = &s->queue;
> +    int size;
> +    int i;
> +    int tmp_data[PS2_QUEUE_SIZE];
> +
> +    /* set the useful data buffer queue size, < PS2_QUEUE_SIZE */
> +    size = q->count > PS2_QUEUE_SIZE ? 0 : q->count;
> +
> +    /* move the queue elements to the start of data array */
> +    if (size > 0) {
> +        for (i = 0; i < size; i++) {
> +            /* move the queue elements to the temporary buffer */
> +            tmp_data[i] = q->data[q->rptr];
> +            if (++q->rptr == 256) {
> +                q->rptr = 0;
> +            }
> +        }
> +        memcpy(q->data, tmp_data, size);
> +    }
> +    /* reset rptr/wptr/count */
> +    q->rptr = 0;
> +    q->wptr = size;
> +    q->count = size;
> +    s->update_irq(s->update_arg, q->count != 0);
> +}
> +
>  static void ps2_kbd_reset(void *opaque)
>  {
>      PS2KbdState *s = (PS2KbdState *) opaque;
> @@ -600,18 +629,31 @@ static const VMStateDescription 
> vmstate_ps2_keyboard_ledstate = {
>  static int ps2_kbd_post_load(void* opaque, int version_id)
>  {
>      PS2KbdState *s = (PS2KbdState*)opaque;
> +    PS2State *ps2 = &s->common;
>  
>      if (version_id == 2)
>          s->scancode_set=2;
> +
> +    ps2_common_post_load(ps2);
> +
>      return 0;
>  }
>  
> +static void ps2_kbd_pre_save(void *opaque)
> +{
> +    PS2KbdState *s = (PS2KbdState *)opaque;
> +    PS2State *ps2 = &s->common;
> +
> +    ps2_common_post_load(ps2);
> +}
> +
>  static const VMStateDescription vmstate_ps2_keyboard = {
>      .name = "ps2kbd",
>      .version_id = 3,
>      .minimum_version_id = 2,
>      .minimum_version_id_old = 2,
>      .post_load = ps2_kbd_post_load,
> +    .pre_save = ps2_kbd_pre_save,
>      .fields      = (VMStateField []) {
>          VMSTATE_STRUCT(common, PS2KbdState, 0, vmstate_ps2_common, PS2State),
>          VMSTATE_INT32(scan_enabled, PS2KbdState),
> @@ -629,11 +671,31 @@ static const VMStateDescription vmstate_ps2_keyboard = {
>      }
>  };
>  
> +static int ps2_mouse_post_load(void *opaque, int version_id)
> +{
> +    PS2MouseState *s = (PS2MouseState *)opaque;
> +    PS2State *ps2 = &s->common;
> +
> +    ps2_common_post_load(ps2);
> +
> +    return 0;
> +}
> +
> +static void ps2_mouse_pre_save(void *opaque)
> +{
> +    PS2MouseState *s = (PS2MouseState *)opaque;
> +    PS2State *ps2 = &s->common;
> +
> +    ps2_common_post_load(ps2);
> +}
> +
>  static const VMStateDescription vmstate_ps2_mouse = {
>      .name = "ps2mouse",
>      .version_id = 2,
>      .minimum_version_id = 2,
>      .minimum_version_id_old = 2,
> +    .post_load = ps2_mouse_post_load,
> +    .pre_save = ps2_mouse_pre_save,
>      .fields      = (VMStateField []) {
>          VMSTATE_STRUCT(common, PS2MouseState, 0, vmstate_ps2_common, 
> PS2State),
>          VMSTATE_UINT8(mouse_status, PS2MouseState),
> -- 
> 1.6.0.2
> 
> 

-- 
                        Amos.