[PATCH v6 0/9] mshv: add SEV-SNP support for MSHV root partitions

[Wei Hu]

This series adds support for creating and managing AMD SEV-SNP
confidential virtual machines through the Microsoft Hypervisor root
partition driver.

The series adds fixed-size MSHV UAPI definitions, the required Microsoft
Hypervisor ABI definitions and hypercall helpers, partition ioctls,
capability discovery, processor-feature handling, ordered encrypted-memory
teardown, and nested-root SynIC handling.

Two prerequisite fixes lead the series. The first makes memory-region
unmap ownership explicit and retains mappings, pinned pages, the partition,
and the module whenever checked hypervisor unmap cannot prove cleanup. The
second publishes and withdraws per-CPU SynIC pointers so interrupt readers
cannot observe mappings after initialization failure or CPU teardown.

Testing:

  - Built all four affected x86 MSHV objects with W=1 at every commit (9/9).
  - Built the complete x86_64 kernel and modules with W=1.
  - Built the affected ARM64 objects with W=1.
  - Ran scripts/checkpatch.pl --strict on every production patch.
  - Verified installed UAPI layouts in 64-bit and 32-bit userspace builds.
  - Generated rust-vmm MSHV bindings for x86_64 and arm64.
  - Passed all 9 KUnit host-access tests on a separate test-only branch.
  - Passed the Cloud Hypervisor single-CVM launch test.
  - Booted a four-vCPU SEV-SNP guest to login; Cloud Hypervisor exited cleanly.

The development host needs two additional local runtime patches to boot as
a nested MSHV root partition: EFI HvLoader root-partition boot enablement
and the non-upstreamable nested-VMBus interrupt-vector workaround. Neither
patch, the KUnit follow-up, nor any runtime-only commit is part of this
nine-patch series.

Changes since v5:

  - In patch 1, keep the existing failed-chunk rollback, then attempt checked
    full-region cleanup for any earlier mapped chunks before quarantining an
    unpublished region. Preserve the original map error and serialize the
    initial movable NO_ACCESS map with mreg_mutex.
  - In patch 6, cap MODIFY_GPA_HOST_ACCESS at 65536 4K array entries. Reject a
    larger request with -E2BIG and completed set to zero before variable
    allocation or side effects. Use sort_nonatomic() and bounded scheduling
    points in long user-controlled loops.
  - Document in patch 6 that a successful PSP request intentionally leaves
    request and response pages host-none for encrypted guest consumption;
    explicit access changes or teardown restore them.
  - In patch 7, use CONFIG_X86_64 for the in-kernel SNP reporting block. Keep
    __x86_64__ in exported UAPI because headers_install rejects CONFIG_* leaks;
    x86_64 and arm64 bindgen output and UAPI layouts remain correct.
  - Classify the reported PSP-success restoration issue as a false positive.
    Findings identified as pre-existing remain unchanged and out of scope.

Link: https://lore.kernel.org/linux-hyperv/20260908121403.1160280-1-weh@xxxxxxxxxxxxxxxxxxx/

Wei Hu (3):
  mshv: retain memory regions until unmap succeeds
  mshv: clear SynIC mappings before freeing them
  mshv: set up own SynIC registers on a nested root partition

Wei Liu (6):
  mshv: add SEV-SNP UAPI definitions
  mshv: add SEV-SNP PSP request hypercall
  mshv: add SEV-SNP isolated page hypercalls
  mshv: wire SEV-SNP partition ioctls
  mshv: detect and report SEV-SNP support at init
  mshv: use safe partition CPU feature defaults

 drivers/hv/mshv_regions.c      |  510 +++++++++---
 drivers/hv/mshv_root.h         |  122 ++-
 drivers/hv/mshv_root_hv_call.c |  369 +++++++--
 drivers/hv/mshv_root_main.c    | 1324 ++++++++++++++++++++++++++++++--
 drivers/hv/mshv_synic.c        |  172 +++--
 include/hyperv/hvgdk_mini.h    |   31 +
 include/hyperv/hvhdk.h         |  124 ++-
 include/hyperv/hvhdk_mini.h    |   53 ++
 include/uapi/linux/mshv.h      |  117 ++-
 9 files changed, 2518 insertions(+), 304 deletions(-)


base-commit: be0cfab740e58b70047ef6e7e3d578f00ed5d258
-- 
2.43.0