[PATCH v3 0/7] mshv: add SEV-SNP support for MSHV root partitions

[Wei Hu <weh@linux.microsoft.com>]

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.

The patches are based on the current hyperv-next branch.

Testing:

  - Built the complete seven-patch series on x86_64.
  - Verified the installed UAPI in 64-bit and 32-bit userspace builds.
  - Generated rust-vmm MSHV bindings from the kernel headers.
  - Booted Linux as an MSHV root partition with SEV-SNP available.
  - Passed Cloud Hypervisor's common_cvm::test_focal_simple_launch.
  - Booted a four-vCPU SEV-SNP guest to login.

The development host needs two additional local patches to boot as a
nested MSHV root partition: the EFI HvLoader enablement and the
non-upstreamable nested-VMBus interrupt-vector workaround. Neither patch
is part of this series.

Changes since v2:

  - Rebase onto current hyperv-next.
  - Drop the system-property structure fix, which is already upstream as
    commit d6f0248f04a9 ("mshv: fix hv_input_get_system_property struct").
  - Drop the EFI HvLoader patch as requested; alternative root-partition
    boot mechanisms will be explored separately.
  - Drop the panic-notifier SNP unlock patch. A panic notifier is not a
    guaranteed pre-crash-kexec hook and cannot safely traverse mutable
    memory-region state in all contexts.
  - Redesign variable-length ioctls to use fixed-size headers and aligned
    userspace pointers. Name GPA and PFN inputs explicitly and add the
    isolated-page size to the UAPI.
  - Replace public bitfields and the large by-value launch payload with a
    naturally aligned pointer-based ABI and field-by-field kernel
    translation.
  - Process userspace page arrays in bounded batches, yield between
    batches, validate large-page alignment and contiguity, and improve
    partial-progress diagnostics.
  - Keep encrypted pages pinned until mappings are removed, the SNP
    partition state is destroyed, and host access is restored. Quarantine
    the partition and retain the module if a safety-critical phase fails.
  - Remove the unbounded delayed-work teardown retry.
  - Treat rejected SNP capability queries (including L1VH) as non-fatal,
    and copy per-CPU results before restoring interrupts.
  - Preserve nested virtualization in the legacy safe feature defaults.
  - Reject device opens until parent-partition initialization completes.
  - Remove redundant SNP operations from the generic passthrough
    hypercall interface.

Link: https://lore.kernel.org/linux-hyperv/20260810124527.1409634-1-weh@linux.microsoft.com/

Wei Hu (1):
  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      |  10 +-
 drivers/hv/mshv_root.h         |  29 ++
 drivers/hv/mshv_root_hv_call.c | 190 +++++++-
 drivers/hv/mshv_root_main.c    | 854 +++++++++++++++++++++++++++++++--
 drivers/hv/mshv_synic.c        |  16 +-
 include/hyperv/hvgdk_mini.h    |  31 ++
 include/hyperv/hvhdk.h         | 124 ++++-
 include/hyperv/hvhdk_mini.h    |  53 ++
 include/uapi/linux/mshv.h      |  99 +++-
 9 files changed, 1365 insertions(+), 41 deletions(-)


base-commit: be0cfab740e58b70047ef6e7e3d578f00ed5d258
-- 
2.43.0