[PATCH RFC 0/3] hw/block/nvme: dif-based end-to-end data protection support

[Klaus Jensen <its@irrelevant.dk>]

From: Klaus Jensen <k.jensen@samsung.com>

This series adds support for extended LBAs and end-to-end data
protection. Marked RFC, since there are a bunch of issues that could use
some discussion.

Storing metadata bytes contiguously with the logical block data and
creating a physically extended logical block basically breaks the DULBE
and deallocation support I just added. Formatting a namespace with
protection information requires the app- and reftags of deallocated or
unwritten blocks to be 0xffff and 0xffffffff respectively; this could be
used to reintroduce DULBE support in that case, albeit at a somewhat
higher cost than the block status flag-based approach.

There is basically three ways of storing metadata (and maybe a forth,
but that is probably quite the endeavour):

  1. Storing metadata as extended blocks directly on the blockdev. That
     is the approach used in this RFC.

  2. Use a separate blockdev. Incidentially, this is also the easiest
     and most straightforward solution to support MPTR-based "separate
     metadata". This also allows DULBE and block deallocation to be
     supported using the existing approach.

  3. A hybrid of 1 and 2 where the metadata is stored contiguously at
    the end of the nvme-ns blockdev.

Option 1 obviously works well with DIF-based protection information and
extended LBAs since it maps one to one. Option 2 works flawlessly with
MPTR-based metadata, but extended LBAs can be "emulated" at the cost of
a bunch of scatter/gather operations.

The 4th option is extending an existing image format (QCOW2) or create
something on top of RAW to supports metadata bytes per block. But both
approaches require full API support through the block layer. And
probably a lot of other stuff that I did not think about.

Anyway, we would love some comments on this.

Gollu Appalanaidu (2):
  nvme: add support for extended LBAs
  hw/block/nvme: end-to-end data protection

Klaus Jensen (1):
  hw/block/nvme: refactor nvme_dma

 hw/block/nvme-ns.h    |  22 +-
 hw/block/nvme.h       |  36 +++
 include/block/nvme.h  |  24 +-
 hw/block/nvme-ns.c    |  66 ++++-
 hw/block/nvme.c       | 616 ++++++++++++++++++++++++++++++++++++++----
 hw/block/trace-events |  10 +
 6 files changed, 704 insertions(+), 70 deletions(-)

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2.29.2