Re: [PATCH v4 09/14] hw/block/nvme: Support Zoned Namespace Command Set

[Klaus Jensen <its@irrelevant.dk>]

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On Sep 24 03:20, Dmitry Fomichev wrote:
> The emulation code has been changed to advertise NVM Command Set when
> "zoned" device property is not set (default) and Zoned Namespace
> Command Set otherwise.
> 
> Handlers for three new NVMe commands introduced in Zoned Namespace
> Command Set specification are added, namely for Zone Management
> Receive, Zone Management Send and Zone Append.
> 
> Device initialization code has been extended to create a proper
> configuration for zoned operation using device properties.
> 
> Read/Write command handler is modified to only allow writes at the
> write pointer if the namespace is zoned. For Zone Append command,
> writes implicitly happen at the write pointer and the starting write
> pointer value is returned as the result of the command. Write Zeroes
> handler is modified to add zoned checks that are identical to those
> done as a part of Write flow.
> 
> The code to support for Zone Descriptor Extensions is not included in
> this commit and ZDES 0 is always reported. A later commit in this
> series will add ZDE support.
> 
> This commit doesn't yet include checks for active and open zone
> limits. It is assumed that there are no limits on either active or
> open zones.
> 
> Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
> Signed-off-by: Hans Holmberg <hans.holmberg@wdc.com>
> Signed-off-by: Ajay Joshi <ajay.joshi@wdc.com>
> Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> Signed-off-by: Matias Bjorling <matias.bjorling@wdc.com>
> Signed-off-by: Aravind Ramesh <aravind.ramesh@wdc.com>
> Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
> Signed-off-by: Adam Manzanares <adam.manzanares@wdc.com>
> Signed-off-by: Dmitry Fomichev <dmitry.fomichev@wdc.com>
> ---
>  block/nvme.c         |    2 +-
>  hw/block/nvme.c      | 1057 ++++++++++++++++++++++++++++++++++++++++--
>  include/block/nvme.h |    6 +-
>  3 files changed, 1026 insertions(+), 39 deletions(-)
> 
> diff --git a/block/nvme.c b/block/nvme.c
> index 05485fdd11..7a513c9a17 100644
> --- a/block/nvme.c
> +++ b/block/nvme.c
> @@ -682,11 +1005,77 @@ static uint16_t nvme_rw(NvmeCtrl *n, NvmeRequest *req)
>          return status;
>      }
>  
> +    if (n->params.zoned) {
> +        zone_idx = nvme_zone_idx(n, slba);
> +        assert(zone_idx < n->num_zones);
> +        zone = &ns->zone_array[zone_idx];
> +
> +        if (is_write) {
> +            status = nvme_check_zone_write(zone, slba, nlb);
> +            if (status != NVME_SUCCESS) {
> +                trace_pci_nvme_err_zone_write_not_ok(slba, nlb, status);
> +                return status | NVME_DNR;
> +            }
> +
> +            assert(nvme_wp_is_valid(zone));
> +            if (append) {
> +                if (unlikely(slba != zone->d.zslba)) {
> +                    trace_pci_nvme_err_append_not_at_start(slba, zone->d.zslba);
> +                    return NVME_ZONE_INVALID_WRITE | NVME_DNR;
> +                }
> +                if (data_size > (n->page_size << n->zasl)) {
> +                    trace_pci_nvme_err_append_too_large(slba, nlb, n->zasl);
> +                    return NVME_INVALID_FIELD | NVME_DNR;
> +                }
> +                slba = zone->w_ptr;
> +            } else if (unlikely(slba != zone->w_ptr)) {
> +                trace_pci_nvme_err_write_not_at_wp(slba, zone->d.zslba,
> +                                                   zone->w_ptr);
> +                return NVME_ZONE_INVALID_WRITE | NVME_DNR;
> +            }
> +            req->fill_ofs = -1LL;
> +        } else {
> +            status = nvme_check_zone_read(n, zone, slba, nlb,
> +                                          n->params.cross_zone_read);
> +            if (status != NVME_SUCCESS) {
> +                trace_pci_nvme_err_zone_read_not_ok(slba, nlb, status);
> +                return status | NVME_DNR;
> +            }
> +
> +            if (slba + nlb > zone->w_ptr) {
> +                /*
> +                 * All or some data is read above the WP. Need to
> +                 * fill out the buffer area that has no backing data
> +                 * with a predefined data pattern (zeros by default)
> +                 */
> +                if (slba >= zone->w_ptr) {
> +                    req->fill_ofs = 0;
> +                } else {
> +                    req->fill_ofs = ((zone->w_ptr - slba) << data_shift);
> +                }

If Read Across Zone Boundaries is enabled and the read in zone A
includes LBAs above the write pointer, but crossing into a full zone
(zone B), then you are gonna overwrite the valid data in zone B with the
fill pattern.

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