Re: [PATCH v2 12/20] nvme: bump supported specification version to 1.3

[Beata Michalska <beata.michalska@linaro.org>]

On Mon, 18 Nov 2019 at 09:48, Klaus Birkelund <its@irrelevant.dk> wrote:
>
> On Tue, Nov 12, 2019 at 03:05:06PM +0000, Beata Michalska wrote:
> > Hi Klaus,
> >
> > On Tue, 15 Oct 2019 at 11:52, Klaus Jensen <its@irrelevant.dk> wrote:
> > >
> > > +static uint16_t nvme_identify_ns_descr_list(NvmeCtrl *n, NvmeCmd *c)
> > > +{
> > > +    static const int len = 4096;
> > > +
> > > +    struct ns_descr {
> > > +        uint8_t nidt;
> > > +        uint8_t nidl;
> > > +        uint8_t rsvd2[2];
> > > +        uint8_t nid[16];
> > > +    };
> > > +
> > > +    uint32_t nsid = le32_to_cpu(c->nsid);
> > > +    uint64_t prp1 = le64_to_cpu(c->prp1);
> > > +    uint64_t prp2 = le64_to_cpu(c->prp2);
> > > +
> > > +    struct ns_descr *list;
> > > +    uint16_t ret;
> > > +
> > > +    trace_nvme_identify_ns_descr_list(nsid);
> > > +
> > > +    if (unlikely(nsid == 0 || nsid > n->num_namespaces)) {
> > > +        trace_nvme_err_invalid_ns(nsid, n->num_namespaces);
> > > +        return NVME_INVALID_NSID | NVME_DNR;
> > > +    }
> > > +
> > In theory this should abort the command for inactive NSIDs as well.
> > But I guess this will come later on.
> >
>
> At this point in the series, the device does not support multiple
> namespaces anyway and num_namespaces is always 1. But this has also been
> reported seperately in relation the patch adding multiple namespaces and
> is fixed in v3.
>
> > > +    list = g_malloc0(len);
> > > +    list->nidt = 0x3;
> > > +    list->nidl = 0x10;
> > > +    *(uint32_t *) &list->nid[12] = cpu_to_be32(nsid);
> > > +
> > Might be worth to add some comment here -> as per the NGUID/EUI64 format.
> > Also those are not specified currently in the namespace identity data structure.
> >
>
> I'll add a comment for why the Namespace UUID is set to this value here.
> The NGUID/EUI64 fields are not set in the namespace identity data
> structure as they are not required. See the descriptions of NGUID and
> EUI64. Here for NGUID:
>
>     "The controller shall specify a globally unique namespace identifier
>     in this field, the EUI64 field, or a Namespace UUID in the Namespace
>     Identification Descriptor..."
>
> Here, I chose to provide it in the Namespace Identification Descriptor
> (by setting `list->nidt = 0x3`).
>
> > > +    ret = nvme_dma_read_prp(n, (uint8_t *) list, len, prp1, prp2);
> > > +    g_free(list);
> > > +    return ret;
> > > +}
> > > +
> > >  static uint16_t nvme_identify(NvmeCtrl *n, NvmeCmd *cmd)
> > >  {
> > >      NvmeIdentify *c = (NvmeIdentify *)cmd;
> > > @@ -934,7 +978,9 @@ static uint16_t nvme_identify(NvmeCtrl *n, NvmeCmd *cmd)
> > >      case 0x01:
> > >          return nvme_identify_ctrl(n, c);
> > >      case 0x02:
> > > -        return nvme_identify_nslist(n, c);
> > > +        return nvme_identify_ns_list(n, c);
> > > +    case 0x03:
> > > +        return nvme_identify_ns_descr_list(n, cmd);
> > >      default:
> > >          trace_nvme_err_invalid_identify_cns(le32_to_cpu(c->cns));
> > >          return NVME_INVALID_FIELD | NVME_DNR;
> > > @@ -1101,6 +1147,14 @@ static uint16_t nvme_set_feature(NvmeCtrl *n, NvmeCmd *cmd, NvmeRequest *req)
> > >          blk_set_enable_write_cache(n->conf.blk, dw11 & 1);
> > >          break;
> > >      case NVME_NUMBER_OF_QUEUES:
> > > +        if (n->qs_created > 2) {
> > > +            return NVME_CMD_SEQ_ERROR | NVME_DNR;
> > > +        }
> > > +
> > I am not sure this is entirely correct as the spec says:
> > "if any I/O Submission and/or Completion Queues (...)"
> > so it might be enough to have a single queue created
> > for this command to be valid.
> > Also I think that the condition here is to make sure that the number
> > of queues requested is being set once at init phase. Currently this will
> > allow the setting to happen if there is no active queue -> so at any
> > point of time (provided the condition mentioned). I might be wrong here
> > but it seems that what we need is a single status saying any queue
> > has been created prior to the Set Feature command at all
> >
>
> Internally, the admin queue pair is counted in qs_created, which is the
> reason for checking if is above 2. The admin queues are created when the
> controller is enabled (mmio write to the EN register in CC).
>
> I'll add a comment about that - I see why it is unclear.
>

Ok, so indeed I have missed the fact that the admin queues are being tracked by
'qs_created'. Still, I might be wrong, but, it is enough to create I/O
submission queue and delete it and the code will allow the command to proceed
Whereas the spec says :
"If a Set Features command is issued for this feature after creation of
any I/O Submission and/or I/O Completion Queues, then the Set Features
command shall fail with status code of Command Sequence Error"

I might be misreading it though but it is not entirely clear to me whether
this is : at least one queue create ... or created and in use.

But I guess that is really minor.

BR
Beata


> >
> > Small note: this patch seems to be introducing more changes
> > than specified in the commit message and especially the subject. Might
> > be worth to extend it a bit.
> >
>
> You are right. I'll split it up.