Re: [PATCH v3 06/15] hw/block/nvme: Add support for Namespace Types

[Klaus Jensen]

On Sep 14 07:14, Dmitry Fomichev wrote:
> From: Niklas Cassel <niklas.cassel@wdc.com>
> 
> Namespace Types introduce a new command set, "I/O Command Sets",
> that allows the host to retrieve the command sets associated with
> a namespace. Introduce support for the command set and enable
> detection for the NVM Command Set.
> 
> The new workflows for identify commands rely heavily on zero-filled
> identify structs. E.g., certain CNS commands are defined to return
> a zero-filled identify struct when an inactive namespace NSID
> is supplied.
> 
> Add a helper function in order to avoid code duplication when
> reporting zero-filled identify structures.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
> ---
>  hw/block/nvme.c | 235 +++++++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 215 insertions(+), 20 deletions(-)
> 
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index 4bd88f4046..d01c1c1e06 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -595,6 +595,33 @@ static inline uint16_t nvme_check_bounds(NvmeCtrl *n, 
> NvmeNamespace *ns,
>      return NVME_SUCCESS;
>  }
>  
> +static void nvme_fill_data(QEMUSGList *qsg, QEMUIOVector *iov,
> +                           uint64_t offset, uint8_t pattern)
> +{
> +    ScatterGatherEntry *entry;
> +    uint32_t len, ent_len;
> +
> +    if (qsg->nsg > 0) {
> +        entry = qsg->sg;
> +        for (len = qsg->size; len > 0; len -= ent_len) {
> +            ent_len = MIN(len, entry->len);
> +            if (offset > ent_len) {
> +                offset -= ent_len;
> +            } else if (offset != 0) {
> +                dma_memory_set(qsg->as, entry->base + offset,
> +                               pattern, ent_len - offset);
> +                offset = 0;
> +            } else {
> +                dma_memory_set(qsg->as, entry->base, pattern, ent_len);
> +            }
> +            entry++;
> +        }
> +    } else if (iov->iov) {
> +        qemu_iovec_memset(iov, offset, pattern,
> +                          iov_size(iov->iov, iov->niov) - offset);
> +    }
> +}
> +
>  static void nvme_rw_cb(void *opaque, int ret)
>  {
>      NvmeRequest *req = opaque;
> @@ -1153,6 +1180,19 @@ static uint16_t nvme_create_cq(NvmeCtrl *n, 
> NvmeRequest *req)
>      return NVME_SUCCESS;
>  }
>  
> +static uint16_t nvme_rpt_empty_id_struct(NvmeCtrl *n, uint64_t prp1,
> +                                         uint64_t prp2, NvmeRequest *req)
> +{
> +    uint16_t status;
> +
> +    status = nvme_map_prp(n, prp1, prp2, NVME_IDENTIFY_DATA_SIZE, req);
> +    if (status) {
> +        return status;
> +    }
> +    nvme_fill_data(&req->qsg, &req->iov, 0, 0);
> +    return NVME_SUCCESS;
> +}
> +

Instead of doing the filling, why not just directly call nvme_dma_prp
with an empty NvmeIdCtrl/NvmeIdNs stack allocated variable?

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