[PATCH v2 0/4] KVM: arm64: selftests: Basic nested guest support

[Wei-Lin Chang <weilin.chang@arm.com>]

Hi,

This is v2 of adding basic support for running nested guests (L2) in
kselftest. After getting feedback from v1 [1], I mostly started over
from scratch. Therefore you won't lose any context if you start here.
Nonetheless, I still compiled the broad changes.

Patch 1 adds GPR save/restore code for guest, and vEL2 exception
vectors.

Patch 2 adds other hypervisor helpers.

Patch 3 adds the hello_nested selftest to jump from vEL2 -> EL1 -> vEL2.

Patch 4 enhances the hello_nested selftest so that vEL1 handles a
hypercall from EL1.

* Changes from v1 [1]:

  - Set HCR_EL2.E2H for the guest.

  - Pivoted from "userspace setting up everything" to "make L1 more like
    a proper hypervisor". Guest EL2 exception vectors, and GPR
    save/restore are added. There is also some infrastructure to
    save/restore system registers, right now only SP_EL1 is
    saved/restored to give L2 a stack. More system registers can be
    added in the future.

  - Removed the stage-2 page table generator. The stage-2 page table
    generator was bad, and the changes needed for the previous point
    alone is already making the series larger, so I decided to not add
    any guest stage-2 code in this iteration.

Thanks!

[1]: https://lore.kernel.org/kvmarm/20260325003620.2214766-1-weilin.chang@arm.com/

Wei-Lin Chang (4):
  KVM: arm64: selftests: Add GPR save/restore functions for NV
  KVM: arm64: sefltests: Add helpers for guest hypervisors
  KVM: arm64: sefltests: Add basic NV selftest
  KVM: arm64: selftests: Enhance hello_nested test

 tools/testing/selftests/kvm/Makefile.kvm      |   4 +
 .../selftests/kvm/arm64/hello_nested.c        | 132 +++++++++++++++++
 .../selftests/kvm/include/arm64/nested.h      |  62 ++++++++
 tools/testing/selftests/kvm/lib/arm64/entry.S | 137 ++++++++++++++++++
 .../selftests/kvm/lib/arm64/hyp-entry.S       |  77 ++++++++++
 .../testing/selftests/kvm/lib/arm64/nested.c  |  58 ++++++++
 6 files changed, 470 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/arm64/hello_nested.c
 create mode 100644 tools/testing/selftests/kvm/include/arm64/nested.h
 create mode 100644 tools/testing/selftests/kvm/lib/arm64/entry.S
 create mode 100644 tools/testing/selftests/kvm/lib/arm64/hyp-entry.S
 create mode 100644 tools/testing/selftests/kvm/lib/arm64/nested.c

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2.43.0