Re: [PATCH] hw/nvme: add param to control auto zone transitioning to zone state closed

[Niklas Cassel <Niklas.Cassel@wdc.com>]

On Mon, Jun 07, 2021 at 11:54:02AM +0200, Klaus Jensen wrote:
> On Jun  1 07:30, Niklas Cassel wrote:
> > On Mon, May 31, 2021 at 09:39:20PM +0200, Klaus Jensen wrote:
> > > On May 31 15:42, Niklas Cassel wrote:
> > > > On Fri, May 28, 2021 at 01:22:38PM +0200, Klaus Jensen wrote:
> > > > > On May 28 11:05, Niklas Cassel wrote:
> > > > > > From: Niklas Cassel <niklas.cassel@wdc.com>
> > > > > >
> > > > > > In the Zoned Namespace Command Set Specification, chapter
> > > > > > 2.5.1 Managing resources
> > > > > >
> > > > > > "The controller may transition zones in the ZSIO:Implicitly Opened state
> > > > > > to the ZSC:Closed state for resource management purposes."
> > > > > >
> > > > > > The word may in this sentence means that automatically transitioning
> > > > > > an implicitly opened zone to closed is completely optional.
> > > > > >
> > > > > > Add a new parameter so that the user can control if this automatic
> > > > > > transitioning should be performed or not.
> > > > > >
> > > > > > Being able to control this can help with verifying that e.g. a user-space
> > > > > > program behaves properly even without this optional ZNS feature.
> > > > > >
> > > > > > The default value is set to true, in order to not change the existing
> > > > > > behavior.
> > > > > >
> > > > > > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> > > > > > ---
> > > > > > hw/nvme/ctrl.c | 9 ++++++++-
> > > > > > hw/nvme/ns.c   | 2 ++
> > > > > > hw/nvme/nvme.h | 1 +
> > > > > > 3 files changed, 11 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> > > > > > index 40a7efcea9..d00f0297a5 100644
> > > > > > --- a/hw/nvme/ctrl.c
> > > > > > +++ b/hw/nvme/ctrl.c
> > > > > > @@ -141,6 +141,11 @@
> > > > > >  *
> > > > > >  *     zoned.cross_read=<enable RAZB, default: false>
> > > > > >  *         Setting this property to true enables Read Across Zone Boundaries.
> > > > > > + *
> > > > > > + *     zoned.auto_transition=<enable auto resource management, default: true>
> > > > > > + *         Indicates if zones in zone state implicitly opened can be
> > > > > > + *         automatically transitioned to zone state closed for resource
> > > > > > + *         management purposes.
> > > > > >  */
> > > > > >
> > > > > > #include "qemu/osdep.h"
> > > > > > @@ -1699,7 +1704,9 @@ static uint16_t nvme_zrm_open_flags(NvmeNamespace *ns, NvmeZone *zone,
> > > > > >         /* fallthrough */
> > > > > >
> > > > > >     case NVME_ZONE_STATE_CLOSED:
> > > > > > -        nvme_zrm_auto_transition_zone(ns);
> > > > > > +        if (ns->params.auto_transition_zones) {
> > > > > > +            nvme_zrm_auto_transition_zone(ns);
> > > > > > +        }
> > > > > >         status = nvme_aor_check(ns, act, 1);
> > > > > >         if (status) {
> > > > > >             return status;
> > > > > > diff --git a/hw/nvme/ns.c b/hw/nvme/ns.c
> > > > > > index 3fec9c6273..31dee43d30 100644
> > > > > > --- a/hw/nvme/ns.c
> > > > > > +++ b/hw/nvme/ns.c
> > > > > > @@ -531,6 +531,8 @@ static Property nvme_ns_props[] = {
> > > > > >                        params.max_open_zones, 0),
> > > > > >     DEFINE_PROP_UINT32("zoned.descr_ext_size", NvmeNamespace,
> > > > > >                        params.zd_extension_size, 0),
> > > > > > +    DEFINE_PROP_BOOL("zoned.auto_transition", NvmeNamespace,
> > > > > > +                     params.auto_transition_zones, true),
> > > > > >     DEFINE_PROP_END_OF_LIST(),
> > > > > > };
> > > > > >
> > > > > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
> > > > > > index 81a35cda14..bd86054db2 100644
> > > > > > --- a/hw/nvme/nvme.h
> > > > > > +++ b/hw/nvme/nvme.h
> > > > > > @@ -100,6 +100,7 @@ typedef struct NvmeNamespaceParams {
> > > > > >     uint32_t max_active_zones;
> > > > > >     uint32_t max_open_zones;
> > > > > >     uint32_t zd_extension_size;
> > > > > > +    bool     auto_transition_zones;
> > > > > > } NvmeNamespaceParams;
> > > > > >
> > > > > > typedef struct NvmeNamespace {
> > > > > > --
> > > > > > 2.31.1
> > > > > >
> > > > >
> > > > > Looks good Niklas!
> > > > >
> > > > > Reviewed-by: Klaus Jensen <k.jensen@samsung.com>
> > > >
> > > > In reality, it is the controller that does the auto transitioning.
> > > >
> > > > In theory, one namespace could be attached to two different controllers,
> > > > and I guess, in that case, it depends on if the controller that we used
> > > > when doing the write supports auto transitioning or not, that determines
> > > > if a zone will be auto transitioned or not.
> > > >
> > > > If we were to change this to be a parameter of the controller instead
> > > > of a parameter of the namespace, we would require to refactor a lot of
> > > > code in the regular write path. As we currently don't have any NvmeRequest
> > > > object in nvme_zrm_open_flags().
> > > >
> > > > Thoughts?
> > > >
> > > 
> > > I think you are right. This should be controller-specific behavior. I took
> > > the liberty of moving the parameter; the refactor is minimal.
> > > 
> > > 
> > > From: Niklas Cassel <niklas.cassel@wdc.com>
> > > 
> > > In the Zoned Namespace Command Set Specification, chapter
> > > 2.5.1 Managing resources
> > > 
> > > "The controller may transition zones in the ZSIO:Implicitly Opened state
> > > to the ZSC:Closed state for resource management purposes."
> > > 
> > > The word may in this sentence means that automatically transitioning
> > > an implicitly opened zone to closed is completely optional.
> > > 
> > > Add a new parameter so that the user can control if this automatic
> > > transitioning should be performed or not.
> > > 
> > > Being able to control this can help with verifying that e.g. a user-space
> > > program behaves properly even without this optional ZNS feature.
> > > 
> > > The default value is set to true, in order to not change the existing
> > > behavior.
> > > 
> > > Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> > > [k.jensen: moved parameter to controller]
> > > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> > > ---
> > >  hw/nvme/nvme.h |  1 +
> > >  hw/nvme/ctrl.c | 32 ++++++++++++++++++++++----------
> > >  2 files changed, 23 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/hw/nvme/nvme.h b/hw/nvme/nvme.h
> > > index 81a35cda142b..93a7e0e5380e 100644
> > > --- a/hw/nvme/nvme.h
> > > +++ b/hw/nvme/nvme.h
> > > @@ -382,6 +382,7 @@ typedef struct NvmeParams {
> > >      uint8_t  vsl;
> > >      bool     use_intel_id;
> > >      uint8_t  zasl;
> > > +    bool     auto_transition_zones;
> > >      bool     legacy_cmb;
> > >  } NvmeParams;
> > > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> > > index 40a7efcea914..8dd9cb2ccbf3 100644
> > > --- a/hw/nvme/ctrl.c
> > > +++ b/hw/nvme/ctrl.c
> > > @@ -34,6 +34,7 @@
> > >   *              aerl=<N[optional]>,aer_max_queued=<N[optional]>, \
> > >   *              mdts=<N[optional]>,vsl=<N[optional]>, \
> > >   *              zoned.zasl=<N[optional]>, \
> > > + *              zoned.auto_transition=<on|off[optional]>, \
> > >   *              subsys=<subsys_id>
> > >   *      -device nvme-ns,drive=<drive_id>,bus=<bus_name>,nsid=<nsid>,\
> > >   *              zoned=<true|false[optional]>, \
> > > @@ -100,6 +101,11 @@
> > >   *   the minimum memory page size (CAP.MPSMIN). The default value is 0 (i.e.
> > >   *   defaulting to the value of `mdts`).
> > >   *
> > > + * - `zoned.auto_transition`
> > > + *   Indicates if zones in zone state implicitly opened can be automatically
> > > + *   transitioned to zone state closed for resource management purposes.
> > > + *   Defaults to 'on'.
> > > + *
> > >   * nvme namespace device parameters
> > >   * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > >   * - `shared`
> > > @@ -1686,8 +1692,8 @@ enum {
> > >      NVME_ZRM_AUTO = 1 << 0,
> > >  };
> > > -static uint16_t nvme_zrm_open_flags(NvmeNamespace *ns, NvmeZone *zone,
> > > -                                    int flags)
> > > +static uint16_t nvme_zrm_open_flags(NvmeCtrl *n, NvmeNamespace *ns,
> > > +                                    NvmeZone *zone, int flags)
> > >  {
> > >      int act = 0;
> > >      uint16_t status;
> > > @@ -1699,7 +1705,9 @@ static uint16_t nvme_zrm_open_flags(NvmeNamespace *ns, NvmeZone *zone,
> > >          /* fallthrough */
> > >      case NVME_ZONE_STATE_CLOSED:
> > > -        nvme_zrm_auto_transition_zone(ns);
> > > +        if (n->params.auto_transition_zones) {
> > > +            nvme_zrm_auto_transition_zone(ns);
> > > +        }
> > >          status = nvme_aor_check(ns, act, 1);
> > >          if (status) {
> > >              return status;
> > > @@ -1735,14 +1743,16 @@ static uint16_t nvme_zrm_open_flags(NvmeNamespace *ns, NvmeZone *zone,
> > >      }
> > >  }
> > > -static inline uint16_t nvme_zrm_auto(NvmeNamespace *ns, NvmeZone *zone)
> > > +static inline uint16_t nvme_zrm_auto(NvmeCtrl *n, NvmeNamespace *ns,
> > > +                                     NvmeZone *zone)
> > >  {
> > > -    return nvme_zrm_open_flags(ns, zone, NVME_ZRM_AUTO);
> > > +    return nvme_zrm_open_flags(n, ns, zone, NVME_ZRM_AUTO);
> > >  }
> > > -static inline uint16_t nvme_zrm_open(NvmeNamespace *ns, NvmeZone *zone)
> > > +static inline uint16_t nvme_zrm_open(NvmeCtrl *n, NvmeNamespace *ns,
> > > +                                     NvmeZone *zone)
> > >  {
> > > -    return nvme_zrm_open_flags(ns, zone, 0);
> > > +    return nvme_zrm_open_flags(n, ns, zone, 0);
> > >  }
> > >  static void nvme_advance_zone_wp(NvmeNamespace *ns, NvmeZone *zone,
> > > @@ -2283,7 +2293,7 @@ static void nvme_copy_in_complete(NvmeRequest *req)
> > >              goto invalid;
> > >          }
> > > -        status = nvme_zrm_auto(ns, zone);
> > > +        status = nvme_zrm_auto(nvme_ctrl(req), ns, zone);
> > >          if (status) {
> > >              goto invalid;
> > >          }
> > > @@ -3080,7 +3090,7 @@ static uint16_t nvme_do_write(NvmeCtrl *n, NvmeRequest *req, bool append,
> > >              goto invalid;
> > >          }
> > > -        status = nvme_zrm_auto(ns, zone);
> > > +        status = nvme_zrm_auto(n, ns, zone);
> > >          if (status) {
> > >              goto invalid;
> > >          }
> > > @@ -3169,7 +3179,7 @@ enum NvmeZoneProcessingMask {
> > >  static uint16_t nvme_open_zone(NvmeNamespace *ns, NvmeZone *zone,
> > >                                 NvmeZoneState state, NvmeRequest *req)
> > >  {
> > > -    return nvme_zrm_open(ns, zone);
> > > +    return nvme_zrm_open(nvme_ctrl(req), ns, zone);
> > >  }
> > >  static uint16_t nvme_close_zone(NvmeNamespace *ns, NvmeZone *zone,
> > > @@ -6259,6 +6269,8 @@ static Property nvme_props[] = {
> > >      DEFINE_PROP_BOOL("use-intel-id", NvmeCtrl, params.use_intel_id, false),
> > >      DEFINE_PROP_BOOL("legacy-cmb", NvmeCtrl, params.legacy_cmb, false),
> > >      DEFINE_PROP_UINT8("zoned.zasl", NvmeCtrl, params.zasl, 0),
> > > +    DEFINE_PROP_BOOL("zoned.auto_transition", NvmeCtrl,
> > > +                     params.auto_transition_zones, true),
> > >      DEFINE_PROP_END_OF_LIST(),
> > >  };
> > > --
> > > 2.31.1
> > > 
> > 
> > Thanks a lot Klaus! I really appreciate it.
> > 
> > My initial thought was to add a new flag in the enum where NVME_ZRM_AUTO is.
> > But I think that would just make the code harder to read.
> > You simply check the parameter directly, which is more obvious to the reader,
> > so I think patch looks good!
> > 
> 
> Can I add your reviewed-by on this? :)

Yes, of course:

Reviewed-by: Niklas Cassel <niklas.cassel@wdc.com>

However, in many projects you can't have a Reviewed-by that is the same as
the author, but perhaps that is not the case in QEMU.


Kind regards,
Niklas