On Tue, Sep 20 2022, Dmitry Fomichev <dmitry.fomic...@wdc.com> wrote:
> 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. Can I get someone more familiar with virtio-blk than me to do a review for this? > > Thank you, > Dmitry > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/143 > > > On Sun, 2022-09-04 at 12:56 -0400, 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-storage . >> >> 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.lem...@opensource.wdc.com> >> Matias Bjørling <matias.bjorl...@wdc.com> >> Niklas Cassel <niklas.cas...@wdc.com> >> Hans Holmberg <hans.holmb...@wdc.com> >> >> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/143 >> Signed-off-by: Dmitry Fomichev <dmitry.fomic...@wdc.com> >> --- >> >> v5 -> v6: >> >> Address review comments from Cornelia Huck: >> >> - add a clause to disallow VIRTIO_BLK_F_ZONED feature to be offered by >> legacy devices >> >> - clarify VIRTIO_BLK_F_DISCARD negotiation procedure for zoned devices >> >> - simplify definitions of constant values that are specific to zoned >> devices >> >> - editorial changes >> >> v4 -> v5: >> >> Add Fixes tag pointing to the corresponding GitHub issue. >> >> Improve the patch changelog. >> >> v3 -> v4: >> >> Address additional feedback from Stefan: >> >> - align the append sector field to 8 bytes instead of 4 >> >> - define "zone sector address" in the non-normative section and use >> this term in the text in a consistent way. Make sure it is clear >> that the value is in bytes. >> >> - move portions of VIRTIO_BLK_T_ZONE_REPORT description to the >> non-normative section >> >> - clarify the wording about reading of unwritten data >> >> - editorial changes >> >> v2 -> v3: >> >> A few changes made as the result of off-list discussions with Stefan, >> Damien and Hannes: >> >> - drop virtblk_zoned_req for zoned devices and define a union for >> virtio request in header that is specific to ZONE APPEND request >> >> - drop support for ALL bit in all zone operations except for RESET >> ZONE. For this zone management operation, define a new request type, >> VIRTIO_BLK_T_ZONE_RESET_ALL. This way, the zone management out >> request header is no longer necessary >> >> - editorial changes >> >> v1 -> v2: >> >> Address Stefan's review comments: >> >> - move normative clauses to normative sections >> >> - remove the "partial" bit in zone report >> >> - change layout of virtio_blk_zoned_req. The "all" flag becomes a bit >> in "zone" bit field struct. This leaves 31 bits for potential future >> extensions. Move the status byte to be the last one in the struct >> >> - set ZBD-specific error codes in the status field, not in >> "zoned_result" field. The former "zoned_result" member now becomes >> "append_sector" >> >> - make a few editorial changes >> --- >> content.tex | 667 +++++++++++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 665 insertions(+), 2 deletions(-) >> >> diff --git a/content.tex b/content.tex >> index 7508dd1..bbc52ad 100644 >> --- a/content.tex >> +++ b/content.tex >> @@ -4557,6 +4557,13 @@ \subsection{Feature bits}\label{sec:Device Types / >> Block >> Device / Feature bits} >> maximum erase sectors count in \field{max_secure_erase_sectors} and >> maximum erase segment number in \field{max_secure_erase_seg}. >> >> +\item[VIRTIO_BLK_F_ZONED(17)] Device is a Zoned Block Device, that is, a >> device >> + that follows the zoned storage device behavior that is also supported >> by >> + industry standards such as the T10 Zoned Block Command standard (ZBC >> r05) or >> + the NVMe(TM) NVM Express Zoned Namespace Command Set Specification >> 1.1b >> + (ZNS). For brevity, these standard documents are referred as "ZBD >> standards" >> + from this point on in the text. >> + >> \end{description} >> >> \subsubsection{Legacy Interface: Feature bits}\label{sec:Device Types / >> Block >> Device / Feature bits / Legacy Interface: Feature bits} >> @@ -4572,6 +4579,11 @@ \subsubsection{Legacy Interface: Feature >> bits}\label{sec:Device Types / Block De >> called VIRTIO_BLK_F_WCE. >> \end{note} >> >> +\begin{note} >> + VIRTIO_BLK_F_ZONED feature cannot be properly negotiated without >> FEATURES_OK >> + bit. Legacy devices MUST NOT offer VIRTIO_BLK_F_ZONED feature bit. >> +\end{note} >> + >> \subsection{Device configuration layout}\label{sec:Device Types / Block >> Device >> / Device configuration layout} >> >> The \field{capacity} of the device (expressed in 512-byte sectors) is always >> @@ -4589,6 +4601,74 @@ \subsection{Device configuration >> layout}\label{sec:Device Types / Block Device / >> \field{max_secure_erase_sectors} \field{secure_erase_sector_alignment} are >> expressed >> in 512-byte units if the VIRTIO_BLK_F_SECURE_ERASE feature bit is >> negotiated. >> >> +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_NONE 0 >> +#define VIRTIO_BLK_Z_HM 1 >> +#define VIRTIO_BLK_Z_HA 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 VIRTIO_BLK_F_ZONED feature while reporting >> VIRTIO_BLK_Z_NONE >> +zoned model commonly do so for testing and development purposes. >> + >> +Host-managed zoned block devices have their LBA range divided to Sequential >> +Write Required (SWR) zones that require some additional handling from the >> host >> +for sustainable operation. All write requests to SWR zones must be >> sequential >> +and the zones with some 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 the 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. >> + >> \begin{lstlisting} >> struct virtio_blk_config { >> le64 capacity; >> @@ -4623,6 +4703,15 @@ \subsection{Device configuration >> layout}\label{sec:Device Types / Block Device / >> le32 max_secure_erase_sectors; >> le32 max_secure_erase_seg; >> le32 secure_erase_sector_alignment; >> + struct virtio_blk_zoned_characteristics { >> + le32 zone_sectors; >> + le32 max_open_zones; >> + le32 max_active_zones; >> + le32 max_append_sectors; >> + le32 write_granularity; >> + u8 model; >> + u8 unused2[3]; >> + } zoned; >> }; >> \end{lstlisting} >> >> @@ -4686,6 +4775,10 @@ \subsection{Device Initialization}\label{sec:Device >> Types / Block Device / Devic >> \field{secure_erase_sector_alignment} can be used by OS when splitting a >> request based on alignment. >> >> +\item If the VIRTIO_BLK_F_ZONED feature is negotiated, the fields in >> + \field{zoned} can be read by the driver to determine the zone >> + characteristics of the device. All \field{zoned} fields are read-only. >> + >> \end{enumerate} >> >> \drivernormative{\subsubsection}{Device Initialization}{Device Types / Block >> Device / Device Initialization} >> @@ -4701,6 +4794,29 @@ \subsection{Device Initialization}\label{sec:Device >> Types / Block Device / Devic >> The driver MUST NOT read \field{writeback} before setting >> the FEATURES_OK \field{device status} bit. >> >> +Drivers SHOULD NOT negotiate VIRTIO_BLK_F_ZONED feature if they are >> incapable >> +of supporting devices with the VIRTIO_BLK_Z_HM or VIRTIO_BLK_Z_HA 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 >> + reads VIRTIO_BLK_Z_HM from the \field{model} field of \field{zoned}, the >> + 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 >> + from the \field{model} field of \field{zoned}, the driver >> + MAY handle the device as a non-zoned device. In this case, the >> + driver SHOULD ignore all other fields in \field{zoned}. >> +\end{itemize} >> + >> \devicenormative{\subsubsection}{Device Initialization}{Device Types / Block >> Device / Device Initialization} >> >> Devices SHOULD always offer VIRTIO_BLK_F_FLUSH, and MUST offer it >> @@ -4712,6 +4828,74 @@ \subsection{Device Initialization}\label{sec:Device >> Types / Block Device / Devic >> The device MUST initialize padding bytes \field{unused0} and >> \field{unused1} to 0. >> >> +If the device that is being initialized is a not a zoned device, the device >> +SHOULD NOT offer the VIRTIO_BLK_F_ZONED feature. >> + >> +If the VIRTIO_BLK_F_ZONED feature is not accepted by the driver, >> +\begin{itemize} >> +\item the device with the VIRTIO_BLK_Z_HA zone model SHOULD proceed with the >> + initialization while setting all zoned characteristics fields to zero. >> + >> +\item the device with the VIRTIO_BLK_Z_HM zone model MUST fail to set the >> + FEATURES_OK device status bit when the driver writes the Device Status >> + 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 >> + 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 >> + block device. >> + >> +\item to the value of VIRTIO_BLK_Z_HA if it operates as a host-aware zoned >> + block device. >> +\end{itemize} >> + >> +If the VIRTIO_BLK_F_ZONED feature is negotiated, >> +\begin{itemize} >> +\item the \field{zone_sectors} field of \field{zoned} MUST be set by the >> device >> + to the size of a single zone on the device. All zones of the device have >> the >> + same size indicated by \field{zone_sectors} except for the last zone >> that >> + MAY be smaller than all other zones. The driver can calculate the number >> of >> + zones on the device as >> + \begin{lstlisting} >> + nr_zones = (capacity + zone_sectors - 1) / zone_sectors; >> + \end{lstlisting} >> + and the size of the last zone as >> + \begin{lstlisting} >> + zs_last = capacity - (nr_zones - 1) * zone_sectors; >> + \end{lstlisting} >> + >> +\item The \field{max_open_zones} field of the \field{zoned} structure MUST >> be >> + set by the device to the maximum number of zones that can be open on the >> + device (zones in the implicit open or explicit open state). A value >> + of zero indicates that the device does not have any limit on the number >> of >> + open zones. >> + >> +\item The \field{max_active_zones} field of the \field{zoned} structure MUST >> + be set by the device to the maximum number zones that can be active on >> the >> + device (zones in the implicit open, explicit open or closed state). A >> value >> + of zero indicates that the device does not have any limit on the number >> of >> + active zones. >> + >> +\item the \field{max_append_sectors} field of \field{zoned} MUST be set by >> + the device to the maximum data size of a VIRTIO_BLK_T_ZONE_APPEND >> request >> + that can be successfully issued to the device. The value of this field >> MUST >> + NOT exceed the \field{seg_max} * \field{size_max} value. A device MAY >> set >> + the \field{max_append_sectors} to zero if it doesn't support >> + VIRTIO_BLK_T_ZONE_APPEND requests. >> + >> +\item the \field{write_granularity} field of \field{zoned} MUST be set by >> the >> + device to the offset and size alignment constraint for VIRTIO_BLK_T_OUT >> + and VIRTIO_BLK_T_ZONE_APPEND requests issued to a sequential zone of the >> + device. >> + >> +\item the device MUST initialize padding bytes \field{unused2} to 0. >> +\end{itemize} >> + >> \subsubsection{Legacy Interface: Device Initialization}\label{sec:Device >> Types >> / Block Device / Device Initialization / Legacy Interface: Device >> Initialization} >> >> Because legacy devices do not have FEATURES_OK, transitional devices >> @@ -4746,7 +4930,15 @@ \subsection{Device Operation}\label{sec:Device Types / >> Block Device / Device Ope >> le32 reserved; >> le64 sector; >> u8 data[]; >> - u8 status; >> + union { >> + u8 status; >> + >> + struct { >> + u8 status; >> + u8 reserved[7]; >> + le64 append_sector; >> + } zone_append_in_hdr; >> + }; >> }; >> \end{lstlisting} >> >> @@ -4770,7 +4962,7 @@ \subsection{Device Operation}\label{sec:Device Types / >> Block Device / Device Ope >> >> The \field{sector} number indicates the offset (multiplied by 512) where >> the 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. >> >> VIRTIO_BLK_T_IN requests populate \field{data} with the contents of sectors >> read from the block device (in multiples of 512 bytes). VIRTIO_BLK_T_OUT >> @@ -4853,6 +5045,299 @@ \subsection{Device Operation}\label{sec:Device Types >> / >> Block Device / Device Ope >> command produces VIRTIO_BLK_S_IOERR. A segment may have completed >> successfully, failed, or not been processed by the device. >> >> +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), an explicit 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_APPEND 15 >> +#define VIRTIO_BLK_T_ZONE_REPORT 16 >> +#define VIRTIO_BLK_T_ZONE_OPEN 18 >> +#define VIRTIO_BLK_T_ZONE_CLOSE 20 >> +#define VIRTIO_BLK_T_ZONE_FINISH 22 >> +#define VIRTIO_BLK_T_ZONE_RESET 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. >> + >> +\begin{lstlisting} >> +#define VIRTIO_BLK_S_ZONE_INVALID_CMD 3 >> +#define VIRTIO_BLK_S_ZONE_UNALIGNED_WP 4 >> +#define VIRTIO_BLK_S_ZONE_OPEN_RESOURCE 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 the zone management commands and is the only request that >> uses >> +\field{zone_append_in_hdr} structure in \field{virtio_blk_req} 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 { >> + le64 nr_zones; >> + u8 reserved[56]; >> + 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 { >> + le64 z_cap; >> + le64 z_start; >> + le64 z_wp; >> + u8 z_type; >> + u8 z_state; >> + u8 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_CONV 1 >> +#define VIRTIO_BLK_ZT_SWR 2 >> +#define VIRTIO_BLK_ZT_SWP 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_WP 0 >> +#define VIRTIO_BLK_ZS_EMPTY 1 >> +#define VIRTIO_BLK_ZS_IOPEN 2 >> +#define VIRTIO_BLK_ZS_EOPEN 3 >> +#define VIRTIO_BLK_ZS_CLOSED 4 >> +#define VIRTIO_BLK_ZS_RDONLY 13 >> +#define VIRTIO_BLK_ZS_FULL 14 >> +#define VIRTIO_BLK_ZS_OFFLINE 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 >> + open zone resource and, additionally, >> + >> +\item a zone in VIRTIO_BLK_ZS_IOPEN, VIRTIO_BLK_ZS_EOPEN and >> + 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 >> + 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 >> + 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 >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_EOPEN when a successful VIRTIO_BLK_T_ZONE_OPEN request >> is >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_CLOSED when a successful VIRTIO_BLK_T_ZONE_CLOSE request >> is >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_CLOSED implicitly by the device when another zone is >> + entering the VIRTIO_BLK_ZS_IOPEN or VIRTIO_BLK_ZS_EOPEN state and the >> number >> + 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 >> + received for the zone. >> + >> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_OUT or >> + VIRTIO_BLK_T_ZONE_APPEND request that causes the zone to reach its >> writable >> + 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 >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_CLOSE request >> is >> + received for the zone and the write pointer of the zone has the value >> equal >> + to the start sector of the zone, >> + >> +\item VIRTIO_BLK_ZS_CLOSED when a successful VIRTIO_BLK_T_ZONE_CLOSE request >> is >> + received for the zone and the zone write pointer is larger then the >> start >> + sector of the zone, >> + >> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_ZONE_FINISH request >> is >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_FULL when a successful VIRTIO_BLK_T_OUT or >> + VIRTIO_BLK_T_ZONE_APPEND request that causes the zone to reach its >> writable >> + 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 >> + received for the zone, >> + >> +\item VIRTIO_BLK_ZS_IOPEN when a successful VIRTIO_BLK_T_OUT request or >> + 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 >> + 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 can transition from this state >> to >> +VIRTIO_BLK_ZS_EMPTY when a successful VIRTIO_BLK_T_ZONE_RESET request is >> +received for the zone >> + >> +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 >> + the zone write pointer. >> + >> +\item the ending sector of the request data multiplied by 512 is not a >> multiple >> + of the value reported by the device in the field >> \field{write_granularity} >> + 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. >> + >> \drivernormative{\subsubsection}{Device Operation}{Device Types / Block >> Device >> / Device Operation} >> >> A driver MUST NOT submit a request which would cause a read or write >> @@ -4899,6 +5384,50 @@ \subsection{Device Operation}\label{sec:Device Types / >> Block Device / Device Ope >> successfully, failed, or were processed by the device at all if the request >> failed with VIRTIO_BLK_S_IOERR. >> >> +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 512 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 >> + by the device in the field \field{write_granularity} in the >> + \field{virtio_blk_zoned_characteristics} configuration space structure. >> + >> +\item the value of the field \field{sector} that is a multiple of the number >> of >> + bytes reported by the device in the field \field{write_granularity} in >> the >> + \field{virtio_blk_zoned_characteristics} configuration space structure. >> + >> +\item the data size that will not exceed the writable zone capacity when its >> + value is added to the current value of the write pointer of the zone. >> + >> +\end{enumerate} >> + >> \devicenormative{\subsubsection}{Device Operation}{Device Types / Block >> Device >> / Device Operation} >> >> A device MUST set the \field{status} byte to VIRTIO_BLK_S_IOERR >> @@ -4990,6 +5519,140 @@ \subsection{Device Operation}\label{sec:Device Types >> / >> Block Device / Device Ope >> simplfy passthrough implementations from eMMC devices. >> \end{note} >> >> +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 with the 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 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{zone_append_in_hdr} field in \field{virtio_blk_req} MUST be set by >> +the device to contain the start sector of the data written to the zone. >> + >> +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 >> + zero by the device, the request SHALL be completed with >> VIRTIO_BLK_S_UNSUPP >> + \field{status}. >> + >> +\item if \field{max_append_sectors} configuration space value is reported as >> + a non-zero value by the device, the request SHALL be completed with >> + 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 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 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 data that is read above the write pointer of a >> zone >> +as unwritten data. The sectors between the write pointer position and the >> upper >> +write boundary of the zone 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 the both 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. >> + >> \subsubsection{Legacy Interface: Device Operation}\label{sec:Device Types / >> Block Device / Device Operation / Legacy Interface: Device Operation} >> When using the legacy interface, transitional devices and drivers >> MUST format the fields in struct virtio_blk_req --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscr...@lists.oasis-open.org For additional commands, e-mail: virtio-dev-h...@lists.oasis-open.org