Re: [PATCH v5 06/14] hw/block/nvme: Add support for active/inactive namespaces

[Niklas Cassel]

On Mon, Sep 28, 2020 at 11:35:20AM +0900, Dmitry Fomichev wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> In NVMe, a namespace is active if it exists and is attached to the
> controller.
> 
> CAP.CSS (together with the I/O Command Set data structure) defines what
> command sets are supported by the controller.
> 
> CC.CSS (together with Set Profile) can be set to enable a subset of the
> available command sets. The namespaces belonging to a disabled command set
> will not be able to attach to the controller, and will thus be inactive.
> 
> E.g., if the user sets CC.CSS to Admin Only, NVM namespaces should be
> marked as inactive.
> 
> The identify namespace, the identify namespace CSI specific, and the namespace
> list commands have two different versions, one that only shows active
> namespaces, and the other version that shows existing namespaces, regardless
> of whether the namespace is attached or not.
> 
> Add an attached member to struct NvmeNamespace, and implement the missing CNS
> commands.
> 
> The added functionality will also simplify the implementation of namespace
> management in the future, since namespace management can also attach and
> detach namespaces.

Following my previous discussion with Klaus,
I think we need to rewrite this commit message completely:

Subject: hw/block/nvme: Add support for allocated CNS command variants

Many CNS commands have "allocated" command variants.
These includes a namespace as long as it is allocated
(i.e. a namespace is included regardless if it is active (attached)
or not.)

While these commands are optional (they are mandatory for controllers
supporting the namespace attachment command), our QEMU implementation
is more complete by actually providing support for these CNS values.

However, since our QEMU model currently does not support the namespace
attachment command, these new allocated CNS commands will return the same
result as the active CNS command variants.

In NVMe, a namespace is active if it exists and is attached to the
controller.

CAP.CSS (together with the I/O Command Set data structure) defines what
command sets are supported by the controller.

CC.CSS (together with Set Profile) can be set to enable a subset of the
available command sets.

Even if a user configures CC.CSS to e.g. Admin only, NVM namespaces
will still be attached (and thus marked as active).
Similarly, if a user configures CC.CSS to e.g. NVM, ZNS namespaces
will still be attached (and thus marked as active).

However, any operation from a disabled command set will result in a
Invalid Command Opcode.

Add an attached struct member for struct NvmeNamespace,
so that we lay the foundation for namespace attachment
support. Also implement logic in the new CNS values to
include/exclude namespaces based on this new struct member.
The only thing missing hooking up the actual Namespace Attachment
command opcode, which allows a user to toggle the attached
variable per namespace. The reason for not hooking up this
command completely is because the NVMe specification
requires that the namespace managment command is supported
if the namespacement attachment command is supported.


> 
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
> ---
>  hw/block/nvme-ns.h   |  1 +
>  hw/block/nvme.c      | 60 ++++++++++++++++++++++++++++++++++++++------
>  include/block/nvme.h | 20 +++++++++------
>  3 files changed, 65 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/block/nvme-ns.h b/hw/block/nvme-ns.h
> index cca23bc0b3..acdb76f058 100644
> --- a/hw/block/nvme-ns.h
> +++ b/hw/block/nvme-ns.h
> @@ -22,6 +22,7 @@
>  typedef struct NvmeNamespaceParams {
>      uint32_t nsid;
>      uint8_t  csi;
> +    bool     attached;
>      QemuUUID uuid;
>  } NvmeNamespaceParams;
>  
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index 4ec1ddc90a..63ad03d6d6 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c

We need to add an additional check in nvme_io_cmd()
that returns Invalid Command Opcode when CC.CSS == Admin only.

> @@ -1523,7 +1523,8 @@ static uint16_t nvme_identify_ctrl_csi(NvmeCtrl *n, 
> NvmeRequest *req)
>      return NVME_INVALID_FIELD | NVME_DNR;
>  }
>  
> -static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeRequest *req)
> +static uint16_t nvme_identify_ns(NvmeCtrl *n, NvmeRequest *req,
> +                                 bool only_active)
>  {
>      NvmeNamespace *ns;
>      NvmeIdentify *c = (NvmeIdentify *)&req->cmd;
> @@ -1540,11 +1541,16 @@ static uint16_t nvme_identify_ns(NvmeCtrl *n, 
> NvmeRequest *req)
>          return nvme_rpt_empty_id_struct(n, req);
>      }
>  
> +    if (only_active && !ns->params.attached) {
> +        return nvme_rpt_empty_id_struct(n, req);
> +    }
> +
>      return nvme_dma(n, (uint8_t *)&ns->id_ns, sizeof(NvmeIdNs),
>                      DMA_DIRECTION_FROM_DEVICE, req);
>  }
>  
> -static uint16_t nvme_identify_ns_csi(NvmeCtrl *n, NvmeRequest *req)
> +static uint16_t nvme_identify_ns_csi(NvmeCtrl *n, NvmeRequest *req,
> +                                     bool only_active)
>  {
>      NvmeNamespace *ns;
>      NvmeIdentify *c = (NvmeIdentify *)&req->cmd;
> @@ -1561,6 +1567,10 @@ static uint16_t nvme_identify_ns_csi(NvmeCtrl *n, 
> NvmeRequest *req)
>          return nvme_rpt_empty_id_struct(n, req);
>      }
>  
> +    if (only_active && !ns->params.attached) {
> +        return nvme_rpt_empty_id_struct(n, req);
> +    }
> +
>      if (c->csi == NVME_CSI_NVM) {
>          return nvme_rpt_empty_id_struct(n, req);
>      }
> @@ -1568,7 +1578,8 @@ static uint16_t nvme_identify_ns_csi(NvmeCtrl *n, 
> NvmeRequest *req)
>      return NVME_INVALID_FIELD | NVME_DNR;
>  }
>  
> -static uint16_t nvme_identify_nslist(NvmeCtrl *n, NvmeRequest *req)
> +static uint16_t nvme_identify_nslist(NvmeCtrl *n, NvmeRequest *req,
> +                                     bool only_active)
>  {
>      NvmeNamespace *ns;
>      NvmeIdentify *c = (NvmeIdentify *)&req->cmd;
> @@ -1598,6 +1609,9 @@ static uint16_t nvme_identify_nslist(NvmeCtrl *n, 
> NvmeRequest *req)
>          if (ns->params.nsid < min_nsid) {
>              continue;
>          }
> +        if (only_active && !ns->params.attached) {
> +            continue;
> +        }
>          list_ptr[j++] = cpu_to_le32(ns->params.nsid);
>          if (j == data_len / sizeof(uint32_t)) {
>              break;
> @@ -1607,7 +1621,8 @@ static uint16_t nvme_identify_nslist(NvmeCtrl *n, 
> NvmeRequest *req)
>      return nvme_dma(n, list, data_len, DMA_DIRECTION_FROM_DEVICE, req);
>  }
>  
> -static uint16_t nvme_identify_nslist_csi(NvmeCtrl *n, NvmeRequest *req)
> +static uint16_t nvme_identify_nslist_csi(NvmeCtrl *n, NvmeRequest *req,
> +                                         bool only_active)
>  {
>      NvmeNamespace *ns;
>      NvmeIdentify *c = (NvmeIdentify *)&req->cmd;
> @@ -1631,6 +1646,9 @@ static uint16_t nvme_identify_nslist_csi(NvmeCtrl *n, 
> NvmeRequest *req)
>          if (ns->params.nsid < min_nsid) {
>              continue;
>          }
> +        if (only_active && !ns->params.attached) {
> +            continue;
> +        }
>          list_ptr[j++] = cpu_to_le32(ns->params.nsid);
>          if (j == data_len / sizeof(uint32_t)) {
>              break;
> @@ -1700,17 +1718,25 @@ static uint16_t nvme_identify(NvmeCtrl *n, 
> NvmeRequest *req)
>  
>      switch (le32_to_cpu(c->cns)) {
>      case NVME_ID_CNS_NS:
> -        return nvme_identify_ns(n, req);
> +        return nvme_identify_ns(n, req, true);
>      case NVME_ID_CNS_CS_NS:
> -        return nvme_identify_ns_csi(n, req);
> +        return nvme_identify_ns_csi(n, req, true);
> +    case NVME_ID_CNS_NS_PRESENT:
> +        return nvme_identify_ns(n, req, false);
> +    case NVME_ID_CNS_CS_NS_PRESENT:
> +        return nvme_identify_ns_csi(n, req, false);
>      case NVME_ID_CNS_CTRL:
>          return nvme_identify_ctrl(n, req);
>      case NVME_ID_CNS_CS_CTRL:
>          return nvme_identify_ctrl_csi(n, req);
>      case NVME_ID_CNS_NS_ACTIVE_LIST:
> -        return nvme_identify_nslist(n, req);
> +        return nvme_identify_nslist(n, req, true);
>      case NVME_ID_CNS_CS_NS_ACTIVE_LIST:
> -        return nvme_identify_nslist_csi(n, req);
> +        return nvme_identify_nslist_csi(n, req, true);
> +    case NVME_ID_CNS_NS_PRESENT_LIST:
> +        return nvme_identify_nslist(n, req, false);
> +    case NVME_ID_CNS_CS_NS_PRESENT_LIST:
> +        return nvme_identify_nslist_csi(n, req, false);
>      case NVME_ID_CNS_NS_DESCR_LIST:
>          return nvme_identify_ns_descr_list(n, req);
>      case NVME_ID_CNS_IO_COMMAND_SET:
> @@ -2188,8 +2214,10 @@ static void nvme_clear_ctrl(NvmeCtrl *n)
>  
>  static int nvme_start_ctrl(NvmeCtrl *n)
>  {
> +    NvmeNamespace *ns;
>      uint32_t page_bits = NVME_CC_MPS(n->bar.cc) + 12;
>      uint32_t page_size = 1 << page_bits;
> +    int i;
>  
>      if (unlikely(n->cq[0])) {
>          trace_pci_nvme_err_startfail_cq();
> @@ -2276,6 +2304,22 @@ static int nvme_start_ctrl(NvmeCtrl *n)
>      nvme_init_sq(&n->admin_sq, n, n->bar.asq, 0, 0,
>                   NVME_AQA_ASQS(n->bar.aqa) + 1);
>  
> +    for (i = 1; i <= n->num_namespaces; i++) {
> +        ns = nvme_ns(n, i);
> +        if (!ns) {
> +            continue;
> +        }
> +        ns->params.attached = false;
> +        switch (ns->params.csi) {
> +        case NVME_CSI_NVM:
> +            if (NVME_CC_CSS(n->bar.cc) == CSS_NVM_ONLY ||
> +                NVME_CC_CSS(n->bar.cc) == CSS_CSI) {
> +                ns->params.attached = true;
> +            }
> +            break;
> +        }
> +    }
> +

Considering that the controller doesn't attach/detach
namespaces belonging to command sets that it doesn't
support, I think a nicer way is to remove this for-loop,
and instead, in nvme_ns_setup() or nvme_ns_init(),
always set attached = true. (Since we currently don't
support namespace attachment command).

The person that implements the last piece of namespace
management and namespace attachment will have to deal
with reading "attached" from some kind of persistent state
and setting it accordingly.

>      nvme_set_timestamp(n, 0ULL);
>  
>      QTAILQ_INIT(&n->aer_queue);
> diff --git a/include/block/nvme.h b/include/block/nvme.h
> index 4587311783..b182fe40b2 100644
> --- a/include/block/nvme.h
> +++ b/include/block/nvme.h
> @@ -804,14 +804,18 @@ typedef struct QEMU_PACKED NvmePSD {
>  #define NVME_IDENTIFY_DATA_SIZE 4096
>  
>  enum NvmeIdCns {
> -    NVME_ID_CNS_NS                = 0x00,
> -    NVME_ID_CNS_CTRL              = 0x01,
> -    NVME_ID_CNS_NS_ACTIVE_LIST    = 0x02,
> -    NVME_ID_CNS_NS_DESCR_LIST     = 0x03,
> -    NVME_ID_CNS_CS_NS             = 0x05,
> -    NVME_ID_CNS_CS_CTRL           = 0x06,
> -    NVME_ID_CNS_CS_NS_ACTIVE_LIST = 0x07,
> -    NVME_ID_CNS_IO_COMMAND_SET    = 0x1c,
> +    NVME_ID_CNS_NS                    = 0x00,
> +    NVME_ID_CNS_CTRL                  = 0x01,
> +    NVME_ID_CNS_NS_ACTIVE_LIST        = 0x02,
> +    NVME_ID_CNS_NS_DESCR_LIST         = 0x03,
> +    NVME_ID_CNS_CS_NS                 = 0x05,
> +    NVME_ID_CNS_CS_CTRL               = 0x06,
> +    NVME_ID_CNS_CS_NS_ACTIVE_LIST     = 0x07,
> +    NVME_ID_CNS_NS_PRESENT_LIST       = 0x10,
> +    NVME_ID_CNS_NS_PRESENT            = 0x11,
> +    NVME_ID_CNS_CS_NS_PRESENT_LIST    = 0x1a,
> +    NVME_ID_CNS_CS_NS_PRESENT         = 0x1b,
> +    NVME_ID_CNS_IO_COMMAND_SET        = 0x1c,
>  };
>  
>  typedef struct QEMU_PACKED NvmeIdCtrl {
> -- 
> 2.21.0
>