While looking at VM bootup times, we stumbled over the fact that the NVMe
code only does I/O operations of up to 4kb at a given point in time. This
is usually ok, but if you have an OS that loads a lot of data on boot in
combination to network backed storage, it shows in bootup times.

There is no need to restrict ourselves to 4kb though. The INT13 call we
receive gives us much larger chunks which we can just map into a native
bigger NVMe I/O call if the request buffer is page aligned.

This patch implements all logic required to do the above and gives a
substantial performance boost on boot.

v1 -> v2:

  - fix dprintf
  - Fix bounds check on PRP list add logic
  - Reduce PRP list to 15 entries embedded in the ns struct.
    This reduces BIOS reserved memory footprint by 4kb.

Alexander Graf (3):
  nvme: Record maximum allowed request size
  nvme: Allow to set PRP2
  nvme: Pass large I/O requests as PRP lists

 src/hw/nvme-int.h |  16 ++++++++-
 src/hw/nvme.c     | 106 +++++++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 105 insertions(+), 17 deletions(-)

-- 
2.16.4




Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879


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