John Snow <js...@redhat.com> writes:
> Currently, if the block device backing the IDE drive is resized,
> the information about the device as cached inside of the IDEState
> structure is not updated, thus when a guest OS re-queries the drive,
> it is unable to see the expanded size.
>
> This patch adds a resize callback that updates the IDENTIFY data
> buffer in order to correct this.
>
> Lastly, a Linux guest as-is cannot resize a libata drive while in-use,
> but it can see the expanded size as part of a bus rescan event.
> This patch also allows guests such as Linux to see the new drive size
> after a soft reboot event, without having to exit the QEMU process.
>
> Signed-off-by: John Snow <js...@redhat.com>
> ---
>
> V2:
> - Do not attempt to update geometry values, to avoid clobbering
> user-specified values, if they exist.
> - Do not regenerate the entire IDENTIFY buffer to avoid losing
> any settings that occurred during normal operation.
>
> hw/ide/core.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index db191a6..ba5e3ad 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -2099,6 +2099,33 @@ static bool ide_cd_is_medium_locked(void *opaque)
> return ((IDEState *)opaque)->tray_locked;
> }
>
> +static void ide_resize_cb(void *opaque)
> +{
> + IDEState *s = opaque;
> + uint16_t *p = (uint16_t *)s->identify_data;
> + uint64_t nb_sectors;
> +
> + if (!s->identify_set) {
> + return;
> + }
> +
> + bdrv_get_geometry(s->bs, &nb_sectors);
> + s->nb_sectors = nb_sectors;
> +
> + /* Update the identify buffer. Note, this is not called for ATAPI. */
> + if (s->drive_kind != IDE_CFATA) {
> + put_le16(p + 60, s->nb_sectors);
> + put_le16(p + 61, s->nb_sectors >> 16);
> + put_le16(p + 100, s->nb_sectors);
> + put_le16(p + 101, s->nb_sectors >> 16);
> + put_le16(p + 102, s->nb_sectors >> 32);
> + put_le16(p + 103, s->nb_sectors >> 48);
> + } else {
> + put_le16(p + 7, s->nb_sectors >> 16);
> + put_le16(p + 8, s->nb_sectors);
> + }
I'd prefer if (s->drive_kind == IDE_CFATA) ... else ..., because it
avoids the double negative.
Your code duplicates the parts of the functions initializing
s->identify_data dealing with nb_sectors. These are:
* ide_identify() for IDE_HD
Writes nb_sectors to slots 60..61 and 100..103. Matches your code.
* ide_atapi_identify() for IDE_CD
Doesn't use it at all. Your code clobbers slots 60..61 and 100.103.
Oops.
* ide_cfata_identify() for IDE_CFATA
Writes nb_sectors to slots 7..8 and and 60..61. Your code only writes
the former.
I guess code duplication is tolerable, because the format of
s->identify_data is unlikely to change. Comments linking the copies
together wouldn't hurt, though.
If we don't want the duplication, we need to factor the length code out
of the identify functions, so we can use it in both places.
[...]
