[PATCH v4 RESEND 0/5] KVM: riscv: Add KVM_PRE_FAULT_MEMORY support

[Jinyu Tang]

Add RISC-V support for the generic KVM_PRE_FAULT_MEMORY ioctl.

Patch 1 and patch 2 fix existing G-stage huge-page corner cases. They
are included first because the prefault hook relies on the map path
reporting the mapping that actually covers the requested GPA.

Patch 3 adds the RISC-V arch hook for KVM_PRE_FAULT_MEMORY. Patch 4 adds
Sv57 indexing support to the RISC-V KVM selftest helpers, and patch 5
enables the generic pre_fault_memory_test for RISC-V.

Patch 1 folds the previously posted standalone G-stage table overwrite
fix into this series:

  https://lore.kernel.org/kvm-riscv/20260814105752.565325-1-jinyu.tang@linux.dev/T/#u

Changes in v4 resend:
- Resend the full series because the previous v4 send was interrupted
  and the kvm-riscv list archive did not show a complete thread. No
  code changes.

Changes in v4:
- Fold the standalone G-stage non-leaf overwrite fix into this series.
- Avoid THP adjustment when the original faulting GPA already has an
  existing 4K G-stage leaf.
- Return an error for HWPOISON instead of reporting success without a
  visible G-stage mapping. (Sashiko)

Changes in v3:
- Retry internally when the map path returns success without a visible
  G-stage mapping, instead of exposing -EAGAIN. (Sashiko)

Changes in v2:
- Drop the per-test guest_modes_append_default() call from
  pre_fault_memory_test.c. (Sean)

Jinyu Tang (5):
  KVM: riscv: Avoid overwriting G-stage tables with huge leaves
  KVM: riscv: Avoid THP adjustment for existing 4K G-stage leaves
  KVM: riscv: Implement KVM_PRE_FAULT_MEMORY
  KVM: selftests: Add RISC-V Sv57 page table indexing
  KVM: selftests: Enable pre_fault_memory_test for RISC-V

 arch/riscv/kvm/Kconfig                        |  1 +
 arch/riscv/kvm/gstage.c                       |  9 ++
 arch/riscv/kvm/mmu.c                          | 83 ++++++++++++++++++-
 arch/riscv/kvm/vm.c                           |  1 +
 tools/testing/selftests/kvm/Makefile.kvm      |  1 +
 .../selftests/kvm/include/riscv/processor.h   |  6 ++
 .../selftests/kvm/lib/riscv/processor.c       |  2 +
 7 files changed, 100 insertions(+), 3 deletions(-)

-- 
2.43.0