Re: [virtio-comment] [PATCH v3] virtio-blk: add secure erase feature to specification

[Cornelia Huck <cohuck@redhat.com>]

On Tue, Nov 30 2021, yadong.qi@intel.com wrote:

> From: Yadong Qi <yadong.qi@intel.com>
>
> There are user requests to use the Linux BLKSECDISCARD ioctl on
> virtio-blk device. A secure discard is the same as a regular discard
> except that all copies of the discarded blocks that were possibly
> created by garbage collection must also be erased. This requires
> support from the device. Hence in this proposal, extend virtio-blk
> protocol to support secure erase command.
>
> Introduced new feature flag and command type:
>     VIRTIO_BLK_F_SECURE_ERASE
>     VIRTIO_BLK_T_SECURE_ERASE
>
> This feature is a passthrough feature on backend because it is hard
> to emulate a secure erase. So virtio-blk will report this feature
> to guest OS if backend device support such kind of feature. And
> when guest OS issues a secure erase command, backend driver will
> passthrough the command to host device blocks.
>
> Introduced new fileds in virtio_blk_config for secure erase commands:
> struct virtio_blk_config {
>     ...
>     max_secure_erase_sectors;
>     max_secure_erase_seg;
>     secure_erase_sector_alignment;
> };
>
> v1 -> v2:
> - add separated queue limits for secure discard.
>
> v2 -> v3:
> - reword "secure discard" to "secure erase".
> - adjust offset of new fields
>
> Signed-off-by: Yadong Qi <yadong.qi@intel.com>
> ---
>  content.tex | 41 +++++++++++++++++++++++++++++++++--------
>  1 file changed, 33 insertions(+), 8 deletions(-)
>
> diff --git a/content.tex b/content.tex
> index 5d112af..dd65024 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -4435,6 +4435,11 @@ \subsection{Feature bits}\label{sec:Device Types / Block Device / Feature bits}
>  
>  \item[VIRTIO_BLK_F_LIFETIME (15)] Device supports providing storage lifetime
>       information.
> +
> +\item[VIRTIO_BLK_F_SECURE_ERASE (16)] Device supports secure discard command,
> +     maximum discard sectors count in \field{max_secure_erase_sectors} and
> +     maximum discard segment number in \field{max_secure_erase_seg}.

This proposed update now has a mixture of "secure erase" and "secure
discard"; this seems confusing to me.

What is the more common name for this feature? I guess we should use it
consistently throughout the spec. Or is a mixture of the two actually
the most common?

> +
>  \end{description}