Re: [PATCH v9] virtio-blk: add zoned block device specification

[Dmitry Fomichev <Dmitry.Fomichev@wdc.com>]

I would like to request the TC vote on the GitHub issue #143 that has been
created to track adding zoned block device support to virtio.

Thank you,
Dmitry

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/143
 
On Wed, 2022-11-09 at 21:51 -0500, Dmitry Fomichev wrote:
> Introduce support for Zoned Block Devices to virtio.
> 
> Zoned Block Devices (ZBDs) aim to achieve a better capacity, latency
> and/or cost characteristics compared to commonly available block
> devices by getting the entire LBA space of the device divided to block
> regions that are much larger than the LBA size. These regions are
> called zones and they can only be written sequentially. More details
> about ZBDs can be found at
> 
> https://zonedstorage.io/docs/introduction/zoned-storageÂ;.
> 
> In its current form, the virtio protocol for block devices (virtio-blk)
> is not aware of ZBDs but it allows the driver to successfully scan a
> host-managed drive provided by the virtio block device. As the result,
> the host-managed drive is recognized by virtio driver as a regular,
> non-zoned drive that will operate erroneously under the most common
> write workloads. Host-aware ZBDs are currently usable, but their
> performance may not be optimal because the driver can only see them as
> non-zoned block devices.
> 
> To fix this, the virtio-blk protocol needs to be extended to add the
> capabilities to convey the zone characteristics of ZBDs at the device
> side to the driver and to provide support for ZBD-specific commands -
> Report Zones, four zone operations (Open, Close, Finish and Reset) and
> (optionally) Zone Append. The proposed standard extension aims to
> define this new functionality.
> 
> This patch extends the virtio-blk section of virtio specification with
> the minimum set of requirements that are necessary to support ZBDs.
> The resulting device model is a subset of the models defined in ZAC/ZBC
> and ZNS standards documents. The included functionality mirrors
> the existing Linux kernel block layer ZBD support and should be
> sufficient to handle the host-managed and host-aware HDDs that are on
> the market today as well as ZNS SSDs that are entering the market at
> the time of submission of this patch.
> 
> I would like to thank the following people for their useful feedback
> and suggestions while working on the initial iterations of this patch.
> 
> Damien Le Moal <damien.lemoal@opensource.wdc.com>
> Matias BjÃrling <Matias.Bjorling@wdc.com>
> Niklas Cassel <Niklas.Cassel@wdc.com>
> Hans Holmberg <Hans.Holmberg@wdc.com>
> 
> Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
> Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
> 
> v8 -> v9:
> 
> Â- add Reviewed-by tag by Damien
> 
> Â- remove the unnecessary Fixes flag
> 
> Â- resend with the version number in the title
> 
> This version is planned to be offered for a vote at the Oasis TC.
> 
> v7 -> v8:
> 
> Avoid normative language in a non-normative section (Stefan)
> 
> v6 -> v7:
> 
> Address review comments from Damien and Stefan:
> 
> Â- change the request layout to make the status always be the last
> ÂÂ byte of the request. The request layout for all ZBD requests except
> ÂÂ Zone Append is now the same as for non-zoned devices. For Zone
> ÂÂ Append, the request layout adds one more field right before the
> ÂÂ status byte and that field is designed to carry over the zone append
> ÂÂ sector from the device to the driver
> 
> Â- describe the operation with F_ZONED feature bit set and the zoned
> ÂÂ model None in terms of drive-managed devices
> 
> Â- add the requirement that the maximum Zone Append data size may not
> ÂÂ be smaller than the write granularity configured for the device
> 
> Â- fix typos and make minor editorial changes
> 
> The Linux kernel driver patchset that is developed to conform to this
> specification version can be found at
> 
> https://www.spinics.net/lists/linux-block/msg91286.html
> 
> v5 -> v6:
> 
> Address review comments from Cornelia Huck:
> 
> Â- add a clause to disallow VIRTIO_BLK_F_ZONED feature to be offered by
> ÂÂ legacy devices
> 
> Â- clarify VIRTIO_BLK_F_DISCARD negotiation procedure for zoned devices
> 
> Â- simplify definitions of constant values that are specific to zoned
> ÂÂ devices
> 
> Â- editorial changes
> 
> v4 -> v5:
> 
> Add Fixes tag pointing to the corresponding GitHub issue.
> 
> Improve the patch changelog.
> 
> v3 -> v4:
> 
> Address additional feedback from Stefan:
> 
> Â- align the append sector field to 8 bytes instead of 4
> 
> Â- define "zone sector address" in the non-normative section and use
> ÂÂ this term in the text in a consistent way. Make sure it is clear
> ÂÂ that the value is in bytes.
> 
> Â- move portions of VIRTIO_BLK_T_ZONE_REPORT description to the
> ÂÂ non-normative section
> 
> Â- clarify the wording about reading of unwritten data
> 
> Â- editorial changes
> 
> v2 -> v3:
> 
> A few changes made as the result of off-list discussions with Stefan,
> Damien and Hannes:
> 
> Â- drop virtblk_zoned_req for zoned devices and define a union for
> ÂÂ virtio request in header that is specific to ZONE APPEND request
> 
> Â- drop support for ALL bit in all zone operations except for RESET
> ÂÂ ZONE. For this zone management operation, define a new request type,
> ÂÂ VIRTIO_BLK_T_ZONE_RESET_ALL. This way, the zone management out
> ÂÂ request header is no longer necessary
> 
> Â- editorial changes
> 
> v1 -> v2:
> 
> Address Stefan's review comments:
> 
> Â- move normative clauses to normative sections
> 
> Â- remove the "partial" bit in zone report
> 
> Â- change layout of virtio_blk_zoned_req. The "all" flag becomes a bit
> ÂÂ in "zone" bit field struct. This leaves 31 bits for potential future
> ÂÂ extensions. Move the status byte to be the last one in the struct
> 
> Â- set ZBD-specific error codes in the status field, not in
> ÂÂ "zoned_result" field. The former "zoned_result" member now becomes
> ÂÂ "append_sector"
> 
> Â- make a few editorial changes
> ---
> Âcontent.tex | 694 +++++++++++++++++++++++++++++++++++++++++++++++++++-
> Â1 file changed, 692 insertions(+), 2 deletions(-)
> 
> diff --git a/content.tex b/content.tex
> index e863709..8330894 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -4655,6 +4655,13 @@ \subsection{Feature bits}\label{sec:Device Types / Block
> Device / Feature bits}
> ÂÂÂÂÂ maximum erase sectors count in \field{max_secure_erase_sectors} and
> ÂÂÂÂÂ maximum erase segment number in \field{max_secure_erase_seg}.
> Â
> +\item[VIRTIO_BLK_F_ZONED(17)] Device is a Zoned Block Device, that is, a
> device
> +ÂÂÂÂÂÂÂthat follows the zoned storage device behavior that is also supported
> by
> +ÂÂÂÂÂÂÂindustry standards such as the T10 Zoned Block Command standard (ZBC
> r05) or
> +ÂÂÂÂÂÂÂthe NVMe(TM) NVM Express Zoned Namespace Command Set Specification 1.1b
> +ÂÂÂÂÂÂÂ(ZNS). For brevity, these standard documents are referred as "ZBD
> standards"
> +ÂÂÂÂÂÂÂfrom this point on in the text.
> +
> Â\end{description}
> Â
> Â\subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / Block
> Device / Feature bits / Legacy Interface: Feature bits}
> @@ -4687,6 +4694,75 @@ \subsection{Device configuration
> layout}\label{sec:Device Types / Block Device /
> Â\field{max_secure_erase_sectors} \field{secure_erase_sector_alignment} are
> expressed
> Âin 512-byte units if the VIRTIO_BLK_F_SECURE_ERASE feature bit is negotiated.
> Â
> +If the VIRTIO_BLK_F_ZONED feature is negotiated, then in
> +\field{virtio_blk_zoned_characteristics},
> +\begin{itemize}
> +\item \field{zone_sectors} value is expressed in 512-byte sectors.
> +\item \field{max_append_sectors} value is expressed in 512-byte sectors.
> +\item \field{write_granularity} value is expressed in bytes.
> +\end{itemize}
> +
> +The \field{model} field in \field{zoned} may have the following values:
> +
> +\begin{lstlisting}
> +#define VIRTIO_BLK_Z_NONEÂÂÂÂÂ 0
> +#define VIRTIO_BLK_Z_HMÂÂÂÂÂÂÂ 1
> +#define VIRTIO_BLK_Z_HAÂÂÂÂÂÂÂ 2
> +\end{lstlisting}
> +
> +Depending on their design, zoned block devices may follow several possible
> +models of operation. The three models that are standardized for ZBDs are
> +drive-managed, host-managed and host-aware.
> +
> +While being zoned internally, drive-managed ZBDs behave exactly like regular,
> +non-zoned block devices. For the purposes of virtio standardization,
> +drive-managed ZBDs can always be treated as non-zoned devices. These devices
> +have the VIRTIO_BLK_Z_NONE model value set in the \field{model} field in
> +\field{zoned}.
> +
> +Devices that offer the VIRTIO_BLK_F_ZONED feature while reporting the
> +VIRTIO_BLK_Z_NONE zoned model are drive-managed zoned block devices. In this
> +case, the driver treats the device as a regular non-zoned block device.
> +
> +Host-managed zoned block devices have their LBA range divided into Sequential
> +Write Required (SWR) zones that require some additional handling by the host
> +for correct operation. All write requests to SWR zones are required be
> +sequential and zones containing some written data need to be reset before that
> +data can be rewritten. Host-managed devices support a set of ZBD-specific I/O
> +requests that can be used by the host to manage device zones. Host-managed
> +devices report VIRTIO_BLK_Z_HM in the \field{model} field in \field{zoned}.
> +
> +Host-aware zoned block devices have their LBA range divided to Sequential
> +Write Preferred (SWP) zones that support random write access, similar to
> +regular non-zoned devices. However, the device I/O performance might not be
> +optimal if SWP zones are used in a random I/O pattern. SWP zones also support
> +the same set of ZBD-specific I/O requests as host-managed devices that allow
> +host-aware devices to be managed by any host that supports zoned block devices
> +to achieve its optimum performance. Host-aware devices report VIRTIO_BLK_Z_HA
> +in the \field{model} field in \field{zoned}.
> +
> +Both SWR zones and SWP zones are sometimes referred as sequential zones.
> +
> +During device operation, sequential zones can be in one of the following
> states:
> +empty, implicitly-open, explicitly-open, closed and full. The state machine
> that
> +governs the transitions between these states is described later in this
> document.
> +
> +SWR and SWP zones consume volatile device resources while being in certain
> +states and the device may set limits on the number of zones that can be in
> these
> +states simultaneously.
> +
> +Zoned block devices use two internal counters to account for the device
> +resources in use, the number of currently open zones and the number of
> currently
> +active zones.
> +
> +Any zone state transition from a state that doesn't consume a zone resource to
> a
> +state that consumes the same resource increments the internal device counter
> for
> +that resource. Any zone transition out of a state that consumes a zone
> resource
> +to a state that doesn't consume the same resource decrements the counter. Any
> +request that causes the device to exceed the reported zone resource limits is
> +terminated by the device with a "zone resources exceeded" error as defined for
> +specific commands later.
> +
> Â\begin{lstlisting}
> Âstruct virtio_blk_config {
> ÂÂÂÂÂÂÂÂ le64 capacity;
> @@ -4721,6 +4797,15 @@ \subsection{Device configuration
> layout}\label{sec:Device Types / Block Device /
> ÂÂÂÂÂÂÂÂ le32 max_secure_erase_sectors;
> ÂÂÂÂÂÂÂÂ le32 max_secure_erase_seg;
> ÂÂÂÂÂÂÂÂ le32 secure_erase_sector_alignment;
> +ÂÂÂÂÂÂÂ struct virtio_blk_zoned_characteristics {
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ le32 zone_sectors;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ le32 max_open_zones;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ le32 max_active_zones;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ le32 max_append_sectors;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ le32 write_granularity;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 model;
> +ÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ u8 unused2[3];
> +ÂÂÂÂÂÂÂ } zoned;
> Â};
> Â\end{lstlisting}
> Â
> @@ -4784,6 +4869,10 @@ \subsection{Device Initialization}\label{sec:Device
> Types / Block Device / Devic
> ÂÂÂÂ \field{secure_erase_sector_alignment} can be used by OS when splitting a
> ÂÂÂÂ request based on alignment.
> Â
> +\item If the VIRTIO_BLK_F_ZONED feature is negotiated, the fields in
> +ÂÂÂ \field{zoned} can be read by the driver to determine the zone
> +ÂÂÂ characteristics of the device. All \field{zoned} fields are read-only.
> +
> Â\end{enumerate}
> Â
> Â\drivernormative{\subsubsection}{Device Initialization}{Device Types / Block
> Device / Device Initialization}
> @@ -4799,6 +4888,30 @@ \subsection{Device Initialization}\label{sec:Device
> Types / Block Device / Devic
> ÂThe driver MUST NOT read \field{writeback} before setting
> Âthe FEATURES_OK \field{device status} bit.
> Â
> +Drivers MUST NOT negotiate the VIRTIO_BLK_F_ZONED feature if they are
> incapable
> +of supporting devices with the VIRTIO_BLK_Z_HM, VIRTIO_BLK_Z_HA or
> +VIRTIO_BLK_Z_NONE zoned model.
> +
> +If the VIRTIO_BLK_F_ZONED feature is offered by the device with the
> +VIRTIO_BLK_Z_HM zone model, then the VIRTIO_BLK_F_DISCARD feature MUST NOT be
> +offered by the driver.
> +
> +If the VIRTIO_BLK_F_ZONED feature and VIRTIO_BLK_F_DISCARD feature are both
> +offered by the device with the VIRTIO_BLK_Z_HA or VIRTIO_BLK_Z_NONE zone
> model,
> +then the driver MAY negotiate these two bits independently.
> +
> +If the VIRTIO_BLK_F_ZONED feature is negotiated, then
> +\begin{itemize}
> +\item if the driver that can not support host-managed zoned devices
> +ÂÂÂ reads VIRTIO_BLK_Z_HM from the \field{model} field of \field{zoned}, the
> +ÂÂÂ driver MUST NOT set FEATURES_OK flag and instead set the FAILED bit.
> +
> +\item if the driver that can not support zoned devices reads VIRTIO_BLK_Z_HA
> +ÂÂÂ from the \field{model} field of \field{zoned}, the driver
> +ÂÂÂ MAY handle the device as a non-zoned device. In this case, the
> +ÂÂÂ driver SHOULD ignore all other fields in \field{zoned}.
> +\end{itemize}
> +
> Â\devicenormative{\subsubsection}{Device Initialization}{Device Types / Block
> Device / Device Initialization}
> Â
> ÂDevices SHOULD always offer VIRTIO_BLK_F_FLUSH, and MUST offer it
> @@ -4810,6 +4923,80 @@ \subsection{Device Initialization}\label{sec:Device
> Types / Block Device / Devic
> ÂThe device MUST initialize padding bytes \field{unused0} and
> Â\field{unused1} to 0.
> Â
> +If the device that is being initialized is a not a zoned device, the device
> +SHOULD NOT offer the VIRTIO_BLK_F_ZONED feature.
> +
> +The VIRTIO_BLK_F_ZONED feature cannot be properly negotiated without
> +FEATURES_OK bit. Legacy devices MUST NOT offer VIRTIO_BLK_F_ZONED feature bit.
> +
> +If the VIRTIO_BLK_F_ZONED feature is not accepted by the driver,
> +\begin{itemize}
> +\item the device with the VIRTIO_BLK_Z_HA or VIRTIO_BLK_Z_NONE zone model
> SHOULD
> +ÂÂÂ proceed with the initialization while setting all zoned characteristics
> +ÂÂÂ fields to zero.
> +
> +\item the device with the VIRTIO_BLK_Z_HM zone model MUST fail to set the
> +ÂÂÂ FEATURES_OK device status bit when the driver writes the Device Status
> +ÂÂÂ field.
> +\end{itemize}
> +
> +If the VIRTIO_BLK_F_ZONED feature is negotiated, then the \field{model} field
> in
> +\field{zoned} struct in the configuration space MUST be set by the device
> +\begin{itemize}
> +\item to the value of VIRTIO_BLK_Z_NONE if it operates as a drive-managed
> +ÂÂÂ zoned block device or a non-zoned block device.
> +
> +\item to the value of VIRTIO_BLK_Z_HM if it operates as a host-managed zoned
> +ÂÂÂ block device.
> +
> +\item to the value of VIRTIO_BLK_Z_HA if it operates as a host-aware zoned
> +ÂÂÂ block device.
> +\end{itemize}
> +
> +If the VIRTIO_BLK_F_ZONED feature is negotiated and the device \field{model}
> +field in \field{zoned} struct is VIRTIO_BLK_Z_HM or VIRTIO_BLK_Z_HA,
> +
> +\begin{itemize}
> +\item the \field{zone_sectors} field of \field{zoned} MUST be set by the
> device
> +ÂÂÂ to the size of a single zone on the device. All zones of the device have
> the
> +ÂÂÂ same size indicated by \field{zone_sectors} except for the last zone that
> +ÂÂÂ MAY be smaller than all other zones. The driver can calculate the number
> of
> +ÂÂÂ zones on the device as
> +ÂÂÂ \begin{lstlisting}
> +ÂÂÂÂÂÂÂ nr_zones = (capacity + zone_sectors - 1) / zone_sectors;
> +ÂÂÂ \end{lstlisting}
> +ÂÂÂ and the size of the last zone as
> +ÂÂÂ \begin{lstlisting}
> +ÂÂÂÂÂÂÂ zs_last = capacity - (nr_zones - 1) * zone_sectors;
> +ÂÂÂ \end{lstlisting}
> +
> +\item The \field{max_open_zones} field of the \field{zoned} structure MUST be
> +ÂÂÂ set by the device to the maximum number of zones that can be open on the
> +ÂÂÂ device (zones in the implicit open or explicit open state). A value
> +ÂÂÂ of zero indicates that the device does not have any limit on the number of
> +ÂÂÂ open zones.
> +
> +\item The \field{max_active_zones} field of the \field{zoned} structure MUST
> +ÂÂÂ be set by the device to the maximum number zones that can be active on the
> +ÂÂÂ device (zones in the implicit open, explicit open or closed state). A
> value
> +ÂÂÂ of zero indicates that the device does not have any limit on the number of
> +ÂÂÂ active zones.
> +
> +\item the \field{max_append_sectors} field of \field{zoned} MUST be set by
> +ÂÂÂ the device to the maximum data size of a VIRTIO_BLK_T_ZONE_APPEND request
> +ÂÂÂ that can be successfully issued to the device. The value of this field
> MUST
> +ÂÂÂ NOT exceed the \field{seg_max} * \field{size_max} value. A device MAY set
> +ÂÂÂ the \field{max_append_sectors} to zero if it doesn't support
> +ÂÂÂ VIRTIO_BLK_T_ZONE_APPEND requests.
> +
> +\item the \field{write_granularity} field of \field{zoned} MUST be set by the
> +ÂÂÂ device to the offset and size alignment constraint for VIRTIO_BLK_T_OUT
> +ÂÂÂ and VIRTIO_BLK_T_ZONE_APPEND requests issued to a sequential zone of the
> +ÂÂÂ device.
> +
> +\item the device MUST initialize padding bytes \field{unused2} to 0.
> +\end{itemize}
> +
> Â\subsubsection{Legacy Interface: Device Initialization}\label{sec:Device Types
> / Block Device / Device Initialization / Legacy Interface: Device
> Initialization}
> Â
> ÂBecause legacy devices do not have FEATURES_OK, transitional devices
> @@ -4836,7 +5023,8 @@ \subsubsection{Legacy Interface: Device
> Initialization}\label{sec:Device Types /
> Â\subsection{Device Operation}\label{sec:Device Types / Block Device / Device
> Operation}
> Â
> ÂThe driver queues requests to the virtqueues, and they are used by
> -the device (not necessarily in order). Each request is of form:
> +the device (not necessarily in order). Each request except
> +VIRTIO_BLK_T_ZONE_APPEND is of form:
> Â
> Â\begin{lstlisting}
> Âstruct virtio_blk_req {
> @@ -4868,7 +5056,7 @@ \subsection{Device Operation}\label{sec:Device Types /
> Block Device / Device Ope
> Â
> ÂThe \field{sector} number indicates the offset (multiplied by 512) where
> Âthe read or write is to occur. This field is unused and set to 0 for
> -commands other than read or write.
> +commands other than read, write and some zone operations.
> Â
> ÂVIRTIO_BLK_T_IN requests populate \field{data} with the contents of sectors
> Âread from the block device (in multiples of 512 bytes). VIRTIO_BLK_T_OUT
> @@ -4951,6 +5139,325 @@ \subsection{Device Operation}\label{sec:Device Types /
> Block Device / Device Ope
> Âcommand produces VIRTIO_BLK_S_IOERR. A segment may have completed
> Âsuccessfully, failed, or not been processed by the device.
> Â
> +The following requirements only apply if the VIRTIO_BLK_F_ZONED feature is
> +negotiated.
> +
> +In addition to the request types defined for non-zoned devices, the type of
> the
> +request can be a zone report (VIRTIO_BLK_T_ZONE_REPORT), an explicit zone open
> +(VIRTIO_BLK_T_ZONE_OPEN), a zone close (VIRTIO_BLK_T_ZONE_CLOSE), a zone
> finish
> +(VIRTIO_BLK_T_ZONE_FINISH), a zone_append (VIRTIO_BLK_T_ZONE_APPEND), a zone
> +reset (VIRTIO_BLK_T_ZONE_RESET) or a zone reset all
> +(VIRTIO_BLK_T_ZONE_RESET_ALL).
> +
> +\begin{lstlisting}
> +#define VIRTIO_BLK_T_ZONE_APPENDÂÂÂ 15
> +#define VIRTIO_BLK_T_ZONE_REPORTÂÂÂ 16
> +#define VIRTIO_BLK_T_ZONE_OPENÂÂÂÂÂ 18
> +#define VIRTIO_BLK_T_ZONE_CLOSEÂÂÂÂ 20
> +#define VIRTIO_BLK_T_ZONE_FINISHÂÂÂ 22
> +#define VIRTIO_BLK_T_ZONE_RESETÂÂÂÂ 24
> +#define VIRTIO_BLK_T_ZONE_RESET_ALL 26
> +\end{lstlisting}
> +
> +Requests of type VIRTIO_BLK_T_OUT, VIRTIO_BLK_T_ZONE_OPEN,
> +VIRTIO_BLK_T_ZONE_CLOSE, VIRTIO_BLK_T_ZONE_FINISH, VIRTIO_BLK_T_ZONE_APPEND,
> +VIRTIO_BLK_T_ZONE_RESET or VIRTIO_BLK_T_ZONE_RESET_ALL may be completed by the
> +device with VIRTIO_BLK_S_OK, VIRTIO_BLK_S_IOERR or VIRTIO_BLK_S_UNSUPP
> +\field{status}, or, additionally, with VIRTIO_BLK_S_ZONE_INVALID_CMD,
> +VIRTIO_BLK_S_ZONE_UNALIGNED_WP, VIRTIO_BLK_S_ZONE_OPEN_RESOURCE or
> +VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE ZBD-specific status codes.
> +
> +Besides the request status, VIRTIO_BLK_T_ZONE_APPEND requests return the
> +starting sector of the appended data back to the driver. For this reason,
> +the VIRTIO_BLK_T_ZONE_APPEND request has the layout that is extended to have
> +the \field{append_sector} field to carry this value:
> +
> +\begin{lstlisting}
> +struct virtio_blk_req_za {
> +ÂÂÂÂÂÂÂ le32 type;
> +ÂÂÂÂÂÂÂ le32 reserved;
> +ÂÂÂÂÂÂÂ le64 sector;
> +ÂÂÂÂÂÂÂ u8 data[];
> +ÂÂÂÂÂÂÂ le64 append_sector;
> +ÂÂÂÂÂÂÂ u8 status;
> +};
> +\end{lstlisting}
> +
> +\begin{lstlisting}
> +#define VIRTIO_BLK_S_ZONE_INVALID_CMDÂÂÂÂ 3
> +#define VIRTIO_BLK_S_ZONE_UNALIGNED_WPÂÂÂ 4
> +#define VIRTIO_BLK_S_ZONE_OPEN_RESOURCEÂÂ 5
> +#define VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE 6
> +\end{lstlisting}
> +
> +Requests of the type VIRTIO_BLK_T_ZONE_REPORT are reads and requests of the
> type
> +VIRTIO_BLK_T_ZONE_APPEND are writes. VIRTIO_BLK_T_ZONE_OPEN,
> +VIRTIO_BLK_T_ZONE_CLOSE, VIRTIO_BLK_T_ZONE_FINISH, VIRTIO_BLK_T_ZONE_RESET and
> +VIRTIO_BLK_T_ZONE_RESET_ALL are non-data requests.
> +
> +Zone sector address is a 64-bit address of the first 512-byte sector of the
> +zone.
> +
> +VIRTIO_BLK_T_ZONE_OPEN, VIRTIO_BLK_T_ZONE_CLOSE, VIRTIO_BLK_T_ZONE_FINISH and
> +VIRTIO_BLK_T_ZONE_RESET requests make the zone operation to act on a
> particular
> +zone specified by the zone sector address in the \field{sector} of the
> request.
> +
> +VIRTIO_BLK_T_ZONE_RESET_ALL request acts upon all applicable zones of the
> +device. The \field{sector} value is not used for this request.
> +
> +In ZBD standards, the VIRTIO_BLK_T_ZONE_REPORT request belongs to "Zone
> +Management Receive" command category and VIRTIO_BLK_T_ZONE_OPEN,
> +VIRTIO_BLK_T_ZONE_CLOSE, VIRTIO_BLK_T_ZONE_FINISH and
> +VIRTIO_BLK_T_ZONE_RESET/VIRTIO_BLK_T_ZONE_RESET_ALL requests are categorized
> as
> +"Zone Management Send" commands. VIRTIO_BLK_T_ZONE_APPEND is categorized
> +separately from zone management commands and is the only request that uses
> +the \field{append_secctor} field \field{virtio_blk_req_za} to return
> +to the driver the sector at which the data has been appended to the zone.
> +
> +VIRTIO_BLK_T_ZONE_REPORT is a read request that returns the information about
> +the current state of zones on the device starting from the zone containing the
> +\field{sector} of the request. The report consists of a header followed by
> zero
> +or more zone descriptors.
> +
> +A zone report reply has the following structure:
> +
> +\begin{lstlisting}
> +struct virtio_blk_zone_report {
> +ÂÂÂÂÂÂÂ le64ÂÂ nr_zones;
> +ÂÂÂÂÂÂÂ u8ÂÂÂÂ reserved[56];
> +ÂÂÂÂÂÂÂ struct virtio_blk_zone_descriptor zones[];
> +};
> +\end{lstlisting}
> +
> +The device sets the \field{nr_zones} field in the report header to the number
> of
> +fully transferred zone descriptors in the data buffer.
> +
> +A zone descriptor has the following structure:
> +
> +\begin{lstlisting}
> +struct virtio_blk_zone_descriptor {
> +ÂÂÂÂÂÂÂ le64ÂÂ z_cap;
> +ÂÂÂÂÂÂÂ le64ÂÂ z_start;
> +ÂÂÂÂÂÂÂ le64ÂÂ z_wp;
> +ÂÂÂÂÂÂÂ u8ÂÂÂÂ z_type;
> +ÂÂÂÂÂÂÂ u8ÂÂÂÂ z_state;
> +ÂÂÂÂÂÂÂ u8ÂÂÂÂ reserved[38];
> +};
> +\end{lstlisting}
> +
> +The zone descriptor field \field{z_type} \field{virtio_blk_zone_descriptor}
> +indicates the type of the zone.
> +
> +The following zone types are available:
> +
> +\begin{lstlisting}
> +#define VIRTIO_BLK_ZT_CONVÂÂÂÂ 1
> +#define VIRTIO_BLK_ZT_SWRÂÂÂÂÂ 2
> +#define VIRTIO_BLK_ZT_SWPÂÂÂÂÂ 3
> +\end{lstlisting}
> +
> +Read and write operations into zones with the VIRTIO_BLK_ZT_CONV
> (Conventional)
> +type have the same behavior as read and write operations on a regular block
> +device. Any block in a conventional zone can be read or written at any time
> and
> +in any order.
> +
> +Zones with VIRTIO_BLK_ZT_SWR can be read randomly, but must be written
> +sequentially at a certain point in the zone called the Write Pointer (WP).
> With
> +every write, the Write Pointer is incremented by the number of sectors
> written.
> +
> +Zones with VIRTIO_BLK_ZT_SWP can be read randomly and should be written
> +sequentially, similarly to SWR zones. However, SWP zones can accept random
> write
> +operations, that is, VIRTIO_BLK_T_OUT requests with a start sector different
> +from the zone write pointer position.
> +
> +The field \field{z_state} of \field{virtio_blk_zone_descriptor} indicates the
> +state of the device zone.
> +
> +The following zone states are available:
> +
> +\begin{lstlisting}
> +#define VIRTIO_BLK_ZS_NOT_WPÂÂ 0
> +#define VIRTIO_BLK_ZS_EMPTYÂÂÂ 1
> +#define VIRTIO_BLK_ZS_IOPENÂÂÂ 2
> +#define VIRTIO_BLK_ZS_EOPENÂÂÂ 3
> +#define VIRTIO_BLK_ZS_CLOSEDÂÂ 4
> +#define VIRTIO_BLK_ZS_RDONLYÂÂ 13
> +#define VIRTIO_BLK_ZS_FULLÂÂÂÂ 14
> +#define VIRTIO_BLK_ZS_OFFLINEÂ 15
> +\end{lstlisting}
> +
> +Zones of the type VIRTIO_BLK_ZT_CONV are always reported by the device to be
> in
> +the VIRTIO_BLK_ZS_NOT_WP state. Zones of the types VIRTIO_BLK_ZT_SWR and
> +VIRTIO_BLK_ZT_SWP can not transition to the VIRTIO_BLK_ZS_NOT_WP state.
> +
> +Zones in VIRTIO_BLK_ZS_EMPTY (Empty), VIRTIO_BLK_ZS_IOPEN (Implicitly Open),
> +VIRTIO_BLK_ZS_EOPEN (Explicitly Open) and VIRTIO_BLK_ZS_CLOSED (Closed) state
> +are writable, but zones in VIRTIO_BLK_ZS_RDONLY (Read-Only),
> VIRTIO_BLK_ZS_FULL
> +(Full) and VIRTIO_BLK_ZS_OFFLINE (Offline) state are not. The write pointer
> +value (\field{z_wp}) is not valid for Read-Only, Full and Offline zones.
> +
> +The zone descriptor field \field{z_cap} contains the maximum number of 512-
> byte
> +sectors that are available to be written with user data when the zone is in
> the
> +Empty state. This value shall be less than or equal to the
> \field{zone_sectors}
> +value in \field{virtio_blk_zoned_characteristics} structure in the device
> +configuration space.
> +
> +The zone descriptor field \field{z_start} contains the zone sector address.
> +
> +The zone descriptor field \field{z_wp} contains the sector address where the
> +next write operation for this zone should be issued. This value is undefined
> +for conventional zones and for zones in VIRTIO_BLK_ZS_RDONLY,
> +VIRTIO_BLK_ZS_FULL and VIRTIO_BLK_ZS_OFFLINE state.
> +
> +Depending on their state, zones consume resources as follows:
> +\begin{itemize}
> +\item a zone in VIRTIO_BLK_ZS_IOPEN and VIRTIO_BLK_ZS_EOPEN state consumes one
> +ÂÂÂ open zone resource and, additionally,
> +
> +\item a zone in VIRTIO_BLK_ZS_IOPEN, VIRTIO_BLK_ZS_EOPEN and
> +ÂÂÂ VIRTIO_BLK_ZS_CLOSED state consumes one active resource.
> +\end{itemize}
> +
> +Attempts for zone transitions that violate zone resource limits must fail with
> +VIRTIO_BLK_S_ZONE_OPEN_RESOURCE or VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE
> +\field{status}.
> +
> +Zones in the VIRTIO_BLK_ZS_EMPTY (Empty) state have the write pointer value
> +equal to the sector address of the zone. In this state, the entire capacity of
> +the zone is available for writing. A zone can transition from this state to
> +\begin{itemize}
> +\item VIRTIO_BLK_ZS_IOPEN when a successful VIRTIO_BLK_T_OUT request or
> +ÂÂÂ VIRTIO_BLK_T_ZONE_APPEND with a non-zero data size is received for the
> zone.
> +
> +\item VIRTIO_BLK_ZS_EOPEN when a successful VIRTIO_BLK_T_ZONE_OPEN request is
> +ÂÂÂ received for the zone
> +\end{itemize}
> +
> +When a VIRTIO_BLK_T_ZONE_RESET request is issued to an Empty zone, the request
> +is completed successfully and the zone stays in the VIRTIO_BLK_ZS_EMPTY state.
> +
> +Zones in the VIRTIO_BLK_ZS_IOPEN (Implicitly Open) state transition from
> +this state to
> +\begin{itemize}
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET request is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET_ALL
> request
> +ÂÂÂ is received by the device,
> +
> +\item VIRTIO_BLK_ZS_EOPEN when a successful VIRTIO_BLK_T_ZONE_OPEN request is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_CLOSED when a successful VIRTIO_BLK_T_ZONE_CLOSE request
> is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_CLOSED implicitly by the device when another zone is
> +ÂÂÂ entering the VIRTIO_BLK_ZS_IOPEN or VIRTIO_BLK_ZS_EOPEN state and the
> number
> +ÂÂÂ of currently open zones is at \field{max_open_zones} limit,
> +
> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_ZONE_FINISH request is
> +ÂÂÂ received for the zone.
> +
> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_OUT or
> +ÂÂÂ VIRTIO_BLK_T_ZONE_APPEND request that causes the zone to reach its
> writable
> +ÂÂÂ capacity is received for the zone.
> +\end{itemize}
> +
> +Zones in the VIRTIO_BLK_ZS_EOPEN (Explicitly Open) state transition from
> +this state to
> +\begin{itemize}
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET request is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET_ALL
> request
> +ÂÂÂ is received by the device,
> +
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_CLOSE request is
> +ÂÂÂ received for the zone and the write pointer of the zone has the value
> equal
> +ÂÂÂ to the start sector of the zone,
> +
> +\item VIRTIO_BLK_ZS_CLOSED when a successful VIRTIO_BLK_T_ZONE_CLOSE request
> is
> +ÂÂÂ received for the zone and the zone write pointer is larger then the start
> +ÂÂÂ sector of the zone,
> +
> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_ZONE_FINISH request is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_OUT or
> +ÂÂÂ VIRTIO_BLK_T_ZONE_APPEND request that causes the zone to reach its
> writable
> +ÂÂÂ capacity is received for the zone.
> +\end{itemize}
> +
> +When a VIRTIO_BLK_T_ZONE_EOPEN request is issued to an Explicitly Open zone,
> the
> +request is completed successfully and the zone stays in the
> VIRTIO_BLK_ZS_EOPEN
> +state.
> +
> +Zones in the VIRTIO_BLK_ZS_CLOSED (Closed) state transition from this state
> +to
> +\begin{itemize}
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET request is
> +ÂÂÂ received for the zone,
> +
> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET_ALL
> request
> +ÂÂÂ is received by the device,
> +
> +\item VIRTIO_BLK_ZS_IOPEN when a successful VIRTIO_BLK_T_OUT request or
> +ÂÂÂ VIRTIO_BLK_T_ZONE_APPEND with a non-zero data size is received for the
> zone.
> +
> +\item VIRTIO_BLK_ZS_EOPEN when a successful VIRTIO_BLK_T_ZONE_OPEN request is
> +ÂÂÂ received for the zone,
> +\end{itemize}
> +
> +When a VIRTIO_BLK_T_ZONE_CLOSE request is issued to a Closed zone, the request
> +is completed successfully and the zone stays in the VIRTIO_BLK_ZS_CLOSED
> state.
> +
> +Zones in the VIRTIO_BLK_ZS_FULL (Full) state transition from this state to
> +VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET request is
> +received for the zone or a successful VIRTIO_BLK_T_ZONE_RESET_ALL request is
> +received by the device.
> +
> +When a VIRTIO_BLK_T_ZONE_FINISH request is issued to a Full zone, the request
> +is completed successfully and the zone stays in the VIRTIO_BLK_ZS_FULL state.
> +
> +The device may automatically transition zones to VIRTIO_BLK_ZS_RDONLY
> +(Read-Only) or VIRTIO_BLK_ZS_OFFLINE (Offline) state from any other state. The
> +device may also automatically transition zones in the Read-Only state to the
> +Offline state. Zones in the Offline state may not transition to any other
> state.
> +Such automatic transitions usually indicate hardware failures. The previously
> +written data may only be read from zones in the Read-Only state. Zones in the
> +Offline state can not be read or written.
> +
> +VIRTIO_BLK_S_ZONE_UNALIGNED_WP is set by the device when the request received
> +from the driver attempts to perform a write to an SWR zone and at least one of
> +the following conditions is met:
> +
> +\begin{itemize}
> +\item the starting sector of the request is not equal to the current value of
> +ÂÂÂ the zone write pointer.
> +
> +\item the ending sector of the request data multiplied by 512 is not a
> multiple
> +ÂÂÂ of the value reported by the device in the field \field{write_granularity}
> +ÂÂÂ in the device configuration space.
> +\end{itemize}
> +
> +VIRTIO_BLK_S_ZONE_OPEN_RESOURCE is set by the device when a zone operation or
> +write request received from the driver can not be handled without exceeding
> the
> +\field{max_open_zones} limit value reported by the device in the configuration
> +space.
> +
> +VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE is set by the device when a zone operation
> or
> +write request received from the driver can not be handled without exceeding
> the
> +\field{max_active_zones} limit value reported by the device in the
> configuration
> +space.
> +
> +A zone transition request that leads to both the \field{max_open_zones} and
> the
> +\field{max_active_zones} limits to be exceeded is terminated by the device
> with
> +VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE \field{status} value.
> +
> +The device reports all other error conditions related to zoned block model
> +operation by setting the VIRTIO_BLK_S_ZONE_INVALID_CMD value in
> +\field{status} of \field{virtio_blk_req} structure.
> +
> Â\drivernormative{\subsubsection}{Device Operation}{Device Types / Block Device
> / Device Operation}
> Â
> ÂThe driver SHOULD check if the content of the \field{capacity} field has
> @@ -5000,6 +5507,50 @@ \subsection{Device Operation}\label{sec:Device Types /
> Block Device / Device Ope
> Âsuccessfully, failed, or were processed by the device at all if the request
> Âfailed with VIRTIO_BLK_S_IOERR.
> Â
> +The following requirements only apply if the VIRTIO_BLK_F_ZONED feature is
> +negotiated.
> +
> +A zone sector address provided by the driver MUST be a multiple of 512 bytes.
> +
> +When forming a VIRTIO_BLK_T_ZONE_REPORT request, the driver MUST set a sector
> +within the sector range of the starting zone to report to \field{sector}
> field.
> +It MAY be a sector that is different from the zone sector address.
> +
> +In VIRTIO_BLK_T_ZONE_OPEN, VIRTIO_BLK_T_ZONE_CLOSE, VIRTIO_BLK_T_ZONE_FINISH
> and
> +VIRTIO_BLK_T_ZONE_RESET requests, the driver MUST set \field{sector} field to
> +point at the first sector in the target zone.
> +
> +In VIRTIO_BLK_T_ZONE_RESET_ALL request, the driver MUST set the field
> +\field{sector} to zero value.
> +
> +The \field{sector} field of the VIRTIO_BLK_T_ZONE_APPEND request MUST specify
> +the zone sector address of the zone to which data is to be appended at the
> +position of the write pointer. The size of the data that is appended MUST be a
> +multiple of \field{write_granularity} bytes and MUST NOT exceed the
> +\field{max_append_sectors} value provided by the device in
> +\field{virtio_blk_zoned_characteristics} configuration space structure.
> +
> +Upon a successful completion of a VIRTIO_BLK_T_ZONE_APPEND request, the driver
> +MAY read the starting sector location of the written data from the request
> +field \field{append_sector}.
> +
> +All VIRTIO_BLK_T_OUT requests issued by the driver to sequential zones and
> +VIRTIO_BLK_T_ZONE_APPEND requests MUST have:
> +
> +\begin{enumerate}
> +\item the data size that is a multiple of the number of bytes reported
> +ÂÂÂ by the device in the field \field{write_granularity} in the
> +ÂÂÂ \field{virtio_blk_zoned_characteristics} configuration space structure.
> +
> +\item the value of the field \field{sector} that is a multiple of the number
> of
> +ÂÂÂ bytes reported by the device in the field \field{write_granularity} in the
> +ÂÂÂ \field{virtio_blk_zoned_characteristics} configuration space structure.
> +
> +\item the data size that will not exceed the writable zone capacity when its
> +ÂÂÂ value is added to the current value of the write pointer of the zone.
> +
> +\end{enumerate}
> +
> Â\devicenormative{\subsubsection}{Device Operation}{Device Types / Block Device
> / Device Operation}
> Â
> ÂThe device MAY change the content of the \field{capacity} field during
> @@ -5095,6 +5646,145 @@ \subsection{Device Operation}\label{sec:Device Types /
> Block Device / Device Ope
> ÂÂ simplfy passthrough implementations from eMMC devices.
> Â\end{note}
> Â
> +If the VIRTIO_BLK_F_ZONED feature is not negotiated, the device MUST reject
> +VIRTIO_BLK_T_ZONE_REPORT, VIRTIO_BLK_T_ZONE_OPEN, VIRTIO_BLK_T_ZONE_CLOSE,
> +VIRTIO_BLK_T_ZONE_FINISH, VIRTIO_BLK_T_ZONE_APPEND, VIRTIO_BLK_T_ZONE_RESET
> and
> +VIRTIO_BLK_T_ZONE_RESET_ALL requests with VIRTIO_BLK_S_UNSUPP status.
> +
> +The following device requirements only apply if the VIRTIO_BLK_F_ZONED feature
> +is negotiated.
> +
> +If a request of type VIRTIO_BLK_T_ZONE_OPEN, VIRTIO_BLK_T_ZONE_CLOSE,
> +VIRTIO_BLK_T_ZONE_FINISH or VIRTIO_BLK_T_ZONE_RESET is issued for a
> Conventional
> +zone (type VIRTIO_BLK_ZT_CONV), the device MUST complete the request with
> +VIRTIO_BLK_S_ZONE_INVALID_CMD \field{status}.
> +
> +If the zone specified by the VIRTIO_BLK_T_ZONE_APPEND request is not a SWR
> zone,
> +then the request SHALL be completed with VIRTIO_BLK_S_ZONE_INVALID_CMD
> +\field{status}.
> +
> +The device handles a VIRTIO_BLK_T_ZONE_OPEN request by attempting to change
> the
> +state of the zone with the \field{sector} address to VIRTIO_BLK_ZS_EOPEN. If
> the
> +transition to this state can not be performed, the request MUST be completed
> +with VIRTIO_BLK_S_ZONE_INVALID_CMD \field{status}. If, while processing this
> +request, the available zone resources are insufficient, then the zone state
> does
> +not change and the request MUST be completed with
> +VIRTIO_BLK_S_ZONE_OPEN_RESOURCE or VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE value in
> +the field \field{status}.
> +
> +The device handles a VIRTIO_BLK_T_ZONE_CLOSE request by attempting to change
> the
> +state of the zone with the \field{sector} address to VIRTIO_BLK_ZS_CLOSED. If
> +the transition to this state can not be performed, the request MUST be
> completed
> +with VIRTIO_BLK_S_ZONE_INVALID_CMD value in the field \field{status}.
> +
> +The device handles a VIRTIO_BLK_T_ZONE_FINISH request by attempting to change
> +the state of the zone with the \field{sector} address to VIRTIO_BLK_ZS_FULL.
> If
> +the transition to this state can not be performed, the zone state does not
> +change and the request MUST be completed with VIRTIO_BLK_S_ZONE_INVALID_CMD
> +value in the field \field{status}.
> +
> +The device handles a VIRTIO_BLK_T_ZONE_RESET request by attempting to change
> the
> +state of the zone with the \field{sector} address to VIRTIO_BLK_ZS_EMPTY
> state.
> +If the transition to this state can not be performed, the zone state does not
> +change and the request MUST be completed with VIRTIO_BLK_S_ZONE_INVALID_CMD
> +value in the field \field{status}.
> +
> +The device handles a VIRTIO_BLK_T_ZONE_RESET_ALL request by transitioning all
> +sequential device zones in VIRTIO_BLK_ZS_IOPEN, VIRTIO_BLK_ZS_EOPEN,
> +VIRTIO_BLK_ZS_CLOSED and VIRTIO_BLK_ZS_FULL state to VIRTIO_BLK_ZS_EMPTY
> state.
> +
> +Upon receiving a VIRTIO_BLK_T_ZONE_APPEND request or a VIRTIO_BLK_T_OUT
> +request issued to a SWR zone in VIRTIO_BLK_ZS_EMPTY or VIRTIO_BLK_ZS_CLOSED
> +state, the device attempts to perform the transition of the zone to
> +VIRTIO_BLK_ZS_IOPEN state before writing data. This transition may fail due to
> +insufficient open and/or active zone resources available on the device. In
> this
> +case, the request MUST be completed with VIRTIO_BLK_S_ZONE_OPEN_RESOURCE or
> +VIRTIO_BLK_S_ZONE_ACTIVE_RESOURCE value in the \field{status}.
> +
> +If the \field{sector} field in the VIRTIO_BLK_T_ZONE_APPEND request does not
> +specify the lowest sector for a zone, then the request SHALL be completed with
> +VIRTIO_BLK_S_ZONE_INVALID_CMD value in \field{status}.
> +
> +A VIRTIO_BLK_T_ZONE_APPEND request or a VIRTIO_BLK_T_OUT request that has the
> +data range that exceeds the remaining writable capacity for the zone, then the
> +request SHALL be completed with VIRTIO_BLK_S_ZONE_INVALID_CMD value in
> +\field{status}.
> +
> +If a request of the type VIRTIO_BLK_T_ZONE_APPEND is completed with
> +VIRTIO_BLK_S_OK status, the field \field{append_sector} in
> +\field{virtio_blk_req_za} MUST be set by the device to contain the first
> sector
> +of the data written to the zone.
> +
> +If a request of the type VIRTIO_BLK_T_ZONE_APPEND is completed with a status
> +other than VIRTIO_BLK_S_OK, the value of \field{append_sector} field in
> +\field{virtio_blk_req_za} is undefined.
> +
> +A VIRTIO_BLK_T_ZONE_APPEND request that has the data size that exceeds
> +\field{max_append_sectors} configuration space value, then,
> +\begin{itemize}
> +\item if \field{max_append_sectors} configuration space value is reported as
> +ÂÂÂ zero by the device, the request SHALL be completed with
> VIRTIO_BLK_S_UNSUPP
> +ÂÂÂ \field{status}.
> +
> +\item if \field{max_append_sectors} configuration space value is reported as
> +ÂÂÂ a non-zero value by the device, the request SHALL be completed with
> +ÂÂÂ VIRTIO_BLK_S_ZONE_INVALID_CMD \field{status}.
> +\end{itemize}
> +
> +If a VIRTIO_BLK_T_ZONE_APPEND request, a VIRTIO_BLK_T_IN request or a
> +VIRTIO_BLK_T_OUT request issued to a SWR zone has the range that has sectors
> in
> +more than one zone, then the request SHALL be completed with
> +VIRTIO_BLK_S_ZONE_INVALID_CMD value in the field \field{status}.
> +
> +A VIRTIO_BLK_T_OUT request that has the \field{sector} value that is not
> aligned
> +with the write pointer for the zone, then the request SHALL be completed with
> +VIRTIO_BLK_S_ZONE_UNALIGNED_WP value in the field \field{status}.
> +
> +In order to avoid resource-related errors while opening zones implicitly, the
> +device MAY automatically transition zones in VIRTIO_BLK_ZS_IOPEN state to
> +VIRTIO_BLK_ZS_CLOSED state.
> +
> +All VIRTIO_BLK_T_OUT requests or VIRTIO_BLK_T_ZONE_APPEND requests issued
> +to a zone in the VIRTIO_BLK_ZS_RDONLY state SHALL be completed with
> +VIRTIO_BLK_S_ZONE_INVALID_CMD \field{status}.
> +
> +All requests issued to a zone in the VIRTIO_BLK_ZS_OFFLINE state SHALL be
> +completed with VIRTIO_BLK_S_ZONE_INVALID_CMD value in the field
> \field{status}.
> +
> +The device MUST consider the sectors that are read between the write pointer
> +position of a zone and the end of the last sector of the zone as unwritten
> data.
> +The sectors between the write pointer position and the end of the last sector
> +within the zone capacity during VIRTIO_BLK_T_ZONE_FINISH request processing
> are
> +also considered unwritten data.
> +
> +When unwritten data is present in the sector range of a read request, the
> device
> +MUST process this data in one of the following ways -
> +
> +\begin{enumerate}
> +\item Fill the unwritten data with a device-specific byte pattern. The
> +configuration, control and reporting of this byte pattern is beyond the scope
> +of this standard. This is the preferred approach.
> +
> +\item Fail the request. Depending on the driver implementation, this may
> prevent
> +the device from becoming operational.
> +\end{enumerate}
> +
> +If both the VIRTIO_BLK_F_ZONED and VIRTIO_BLK_F_SECURE_ERASE features are
> +negotiated, then
> +
> +\begin{enumerate}
> +\item the field \field{secure_erase_sector_alignment} in the configuration
> space
> +of the device MUST be a multiple of \field{zone_sectors} value reported in the
> +device configuration space.
> +
> +\item the data size in VIRTIO_BLK_T_SECURE_ERASE requests MUST be a multiple
> of
> +\field{zone_sectors} value in the device configuration space.
> +\end{enumerate}
> +
> +The device MUST handle a VIRTIO_BLK_T_SECURE_ERASE request in the same way it
> +handles VIRTIO_BLK_T_ZONE_RESET request for the zone range specified in the
> +VIRTIO_BLK_T_SECURE_ERASE request.
> +
> Â\subsubsection{Legacy Interface: Device Operation}\label{sec:Device Types /
> Block Device / Device Operation / Legacy Interface: Device Operation}
> ÂWhen using the legacy interface, transitional devices and drivers
> ÂMUST format the fields in struct virtio_blk_req