[PATCH v3 0/3] Drivers: hv: decrypt netvsc buffers on contiguous direct-map addresses

[Kameron Carr <kameroncarr@linux.microsoft.com>]

Arm CCA Realms implement set_memory_decrypted() only for addresses in the
kernel linear map; vmalloc()/vmap() addresses are rejected. netvsc
allocates its large send and receive buffers with vzalloc() and passes
those addresses to vmbus_establish_gpadl(), which calls
set_memory_decrypted(), causing GPADL establishment to fail in a Realm.

This series allocates shared buffers as a list of chunks, each physically
contiguous, decrypts each chunk through its direct-map address, and
combines them into a virtually contiguous mapping with vmap(). Private
buffers continue to use vzalloc().

Changes since v1 [1]:
  Patch 1:
    - Add HV_GPADL_BUFFER_DECRYPTED to enum hv_gpadl_type to indicate a
      buffer that has already been decrypted.
  Patch 2:
    - Rename netvsc_{alloc,free}_buf_pages() -> vmbus_{alloc,free}_buffer()
      and move them to channel.c. 
    - Remove struct netvsc_buf_chunk and replace with page folio in
      compound pages.
    - vmbus_alloc_buffer():
      - use vzalloc() for non-host-visible buffers and remove the
        encryption decision out of netvsc.
      - min_t() -> min().
      - zero the memory after allocation.
      - specify @size "will be rounded up to PAGE_SIZE" in the docstring.

Changes since v2 [2]:
  Patch 2:
    - Split patch into two patches, separating new helper functions in 
      VMBus from the netvsc driver changes.
    - Change `nr_pages`, `remaining`, and `page_idx` to unsigned long to
      avoid casting.
    - Move `order` initialization to the top of vmbus_alloc_buffer(),
      removing one min() call.
    - Change `order` to a signed int to avoid needing min_t().
    - Restructure loop in vmbus_alloc_buffer() to avoid nested loops and
      simplify logic.
    - Small comment changes.

[1]: https://lore.kernel.org/all/20260721195633.1438361-1-kameroncarr@linux.microsoft.com/
[2]: https://lore.kernel.org/all/20260730233359.3850612-1-kameroncarr@linux.microsoft.com/


Kameron Carr (3):
  Drivers: hv: vmbus: add vmbus_establish_gpadl_caller_decrypted()
  hv: vmbus: Add vmbus_alloc_buffer()/vmbus_free_buffer() for CoCo VMs
  hv_netvsc: Allocate host-visible GPADL buffers using
    vmbus_alloc_buffer()

 drivers/hv/channel.c            | 182 +++++++++++++++++++++++++++++++-
 drivers/net/hyperv/hyperv_net.h |   8 +-
 drivers/net/hyperv/netvsc.c     | 104 ++++++++++++------
 drivers/net/hyperv/netvsc_drv.c |   6 ++
 include/linux/hyperv.h          |  15 ++-
 5 files changed, 278 insertions(+), 37 deletions(-)


base-commit: a4ffc59238be84dd1c26bf1c001543e832674fc6
-- 
2.45.4