Re: [Qemu-devel] [PATCH] ide: Check validity of logical block size

[John Snow <jsnow@redhat.com>]

On 12/03/2014 07:35 AM, Kevin Wolf wrote:
> Our IDE emulation can't handle logical block sizes other than 512. Check
> for it.
>
> The original assumption was that other values would silently be ignored
> (which is bad enough), but it's not quite true: The physical block size
> is exposed in IDENTIFY DEVICE as a multiple of the logical block size.
> Setting a logical block size therefore also corrupts the physical block
> size (4096/4096 doesn't silently downgrade to 4096/512, but 512/512).
>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   hw/ide/qdev.c | 5 +++++
>   1 file changed, 5 insertions(+)
>
> diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
> index b4f096e..1ebb58d 100644
> --- a/hw/ide/qdev.c
> +++ b/hw/ide/qdev.c
> @@ -163,6 +163,11 @@ static int ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind)
>           return -1;
>       }
>
> +    if (dev->conf.logical_block_size != 512) {
> +        error_report("logical_block_size must be 512 for IDE");
> +        return -1;
> +    }
> +
>       blkconf_serial(&dev->conf, &dev->serial);
>       if (kind != IDE_CD) {
>           blkconf_geometry(&dev->conf, &dev->chs_trans, 65536, 16, 255, &err);
>

There are so many 512 literals in the IDE code that I actually assumed 
we already enforced this, or otherwise just always used 512 regardless.

Reviewed-by: John Snow <jsnow@redhat.com>