[v3] cirrus_vga: adding sanity check for vram size

From: Gonglei <arei.gonglei@huawei.com>

when configure a invalid vram size for cirrus card, such as less
2 MB, which will crash qemu. Follow the real hardware, the cirrus
card has 4 MB video memory. Also for backward compatibility, accept
8 MB and 16 MB vram size.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
---
v3: 
 - fix logic bug pointed out by Michael Tokarev
 - add the same restriction for ISA cirrus device, thanks Andreas
v2: 
 - fix checkpatch fails.
   "WARNING: suspect code indent for conditional statements (5, 9)"
   maybe not a real warning.
 
 hw/display/cirrus_vga.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

Am 12.05.2014 09:10, schrieb arei.gonglei@huawei.com:
> From: Gonglei <arei.gonglei@huawei.com>
> 
> when configure a invalid vram size for cirrus card, such as less
> 2 MB, which will crash qemu. Follow the real hardware, the cirrus
> card has 4 MB video memory. Also for backward compatibility, accept
> 8 MB and 16 MB vram size.
> 
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
> v3: 
>  - fix logic bug pointed out by Michael Tokarev
>  - add the same restriction for ISA cirrus device, thanks Andreas
> v2: 
>  - fix checkpatch fails.
>    "WARNING: suspect code indent for conditional statements (5, 9)"
>    maybe not a real warning.
>  
>  hw/display/cirrus_vga.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)

Thanks,

Reviewed-by: Andreas Färber <afaerber@suse.de>

> diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
> index d1afc76..ca0d786 100644
> --- a/hw/display/cirrus_vga.c
> +++ b/hw/display/cirrus_vga.c
> @@ -2913,6 +2913,14 @@ static void isa_cirrus_vga_realizefn(DeviceState *dev, Error **errp)
>      ISACirrusVGAState *d = ISA_CIRRUS_VGA(dev);
>      VGACommonState *s = &d->cirrus_vga.vga;
>  
> +    /* follow real hardware, cirrus card emulated has 4 MB video memory.
> +       Also accept 8 MB/16 MB for backward compatibility. */
> +    if (s->vram_size_mb != 4 && s->vram_size_mb != 8 &&
> +        s->vram_size_mb != 16) {
> +        error_setg(errp, "Invalid cirrus_vga ram size '%u'",
> +                   s->vram_size_mb);
> +        return;
> +    }
>      vga_common_init(s, OBJECT(dev), true);
>      cirrus_init_common(&d->cirrus_vga, OBJECT(dev), CIRRUS_ID_CLGD5430, 0,
>                         isa_address_space(isadev),
> @@ -2959,6 +2967,14 @@ static int pci_cirrus_vga_initfn(PCIDevice *dev)
>       PCIDeviceClass *pc = PCI_DEVICE_GET_CLASS(dev);
>       int16_t device_id = pc->device_id;
>  
> +     /* follow real hardware, cirrus card emulated has 4 MB video memory.
> +       Also accept 8 MB/16 MB for backward compatibility. */

This line looks off by one, maybe Gerd can edit before applying?

Note that in general
/*
 *
 */
comment style is preferred (stars on each line) but I don't spot a hard
requirement in CODING_STYLE or HACKING. :)

Cheers,
Andreas

> +     if (s->vga.vram_size_mb != 4 && s->vga.vram_size_mb != 8 &&
> +         s->vga.vram_size_mb != 16) {
> +         error_report("Invalid cirrus_vga ram size '%u'",
> +                      s->vga.vram_size_mb);
> +         return -1;
> +     }
>       /* setup VGA */
>       vga_common_init(&s->vga, OBJECT(dev), true);
>       cirrus_init_common(s, OBJECT(dev), device_id, 1, pci_address_space(dev),

On Mo, 2014-05-12 at 15:10 +0800, arei.gonglei@huawei.com wrote:
> From: Gonglei <arei.gonglei@huawei.com>
> 
> when configure a invalid vram size for cirrus card, such as less
> 2 MB, which will crash qemu. Follow the real hardware, the cirrus
> card has 4 MB video memory. Also for backward compatibility, accept
> 8 MB and 16 MB vram size.

Added to vga queue.

thanks,
  Gerd