[PATCH v2 0/2] KVM: selftests: SEV: address two TODOs in the SEV tests

[Hemanth Selam <hemanth.selam@gmail.com>]

This small series fills in two pre-existing TODOs in the x86 SEV
selftests. Both are test-only changes; there is no functional change to
the kernel.

Patch 1 adds negative coverage to sev_init2_tests: when the platform
does not support a given SEV VM type (SEV-ES or SEV-SNP), it verifies
that KVM_CREATE_VM rejects that type with -EINVAL. Previously the test
only exercised the VM types that were supported, so a mismatch between
KVM_CAP_VM_TYPES and the actual KVM_CREATE_VM enforcement would have
gone unnoticed.

Patch 2 makes sev_smoke_test capture the launch measurement returned by
KVM_SEV_LAUNCH_MEASURE for SEV and SEV-ES guests and asserts that it is
not all zeros, instead of discarding it. A full attestation-style
validation is not possible from the selftest (userspace does not hold
the transport keys used to derive the measurement), but a non-zero
check catches a PSP/plumbing failure that silently leaves the buffer
untouched. SEV-SNP uses a different launch flow and is skipped.

Testing: built and run on an AMD EPYC 9755 (Turin) host running this
tree (7.2.0-rc2), with sev/sev_es/sev_snp all enabled. Both tests pass.
The new rejection path was additionally exercised by reloading kvm_amd
with sev_snp=0 so the unsupported types are rejected: under strace,
KVM_CREATE_VM for the SEV-ES and SNP types both return -EINVAL and the
test passes. checkpatch --strict is clean on both patches.

Changes in v2:
 - Patch 1: fix unreachable fd cleanup in test_create_invalid_type().
   TEST_ASSERT() aborts on failure, so the trailing "if (fd >= 0)
   close(fd)" could never run; close the fd (and latch errno) before
   the assert instead, so an unexpectedly-created VM is not leaked.
   Reported-by: Sashiko AI review.
 - Trimmed the added in-code comments to short high-level notes and
   moved the detailed rationale into the commit messages.
 - No functional change to patch 2.

v1: https://lore.kernel.org/all/20260709164751.621326-1-hemanth.selam@gmail.com/

Hemanth Selam (2):
  KVM: selftests: SEV: Verify unsupported VM types are rejected at
    creation
  KVM: selftests: SEV: Sanity check the launch measurement

 .../selftests/kvm/x86/sev_init2_tests.c       | 27 +++++++++++++++++--
 .../selftests/kvm/x86/sev_smoke_test.c        | 23 +++++++++++++++--
 2 files changed, 46 insertions(+), 4 deletions(-)

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2.43.7