[PATCH v2 0/2] KVM: riscv: Fix hugetlb G-stage block mapping eligibility

[Jinyu Tang]

RISC-V KVM checks memslot alignment and head/tail coverage before
installing THP-backed PMD G-stage block mappings, but the hugetlb path
has used the hugetlb VMA size directly. That can be wrong for memslots
whose HVA and GPA have different offsets within the target block, or for
partial head/tail blocks.

Generalize the existing block eligibility helper so it can check a
caller-provided target size, use it to select hugetlb mappings with a
PUD -> PMD -> PAGE_SIZE fallback, and add a selftest mode that creates a
hugetlb memslot with a deliberate HVA/GPA offset mismatch.

Tested on a QEMU RISC-V host with 8 pre-allocated 2MB hugepages:

  # ./kvm_page_table_test -m 19 -s anonymous -b 4M -v 1
  # ./kvm_page_table_test -m 19 -s anonymous_hugetlb_2mb -b 4M -v 1
  # timeout 30s ./kvm_page_table_test \
        -m 19 -s anonymous_hugetlb_2mb -b 4M -v 1 -u

  base + selftest:
    anonymous:                 PASS
    aligned hugetlb:           PASS
    misaligned hugetlb:        timeout

  patched:
    anonymous:                 PASS
    aligned hugetlb:           PASS
    misaligned hugetlb:        PASS

v1 -> v2:
  - Squash the helper parameterization into the hugetlb fix
  - Use the ALIGN()/ALIGN_DOWN() form suggested by Nutty Liu and Anup
    for the memslot boundary check.

Jinyu Tang (2):
  KVM: riscv: Check hugetlb block mappings against memslot bounds
  KVM: selftests: Add a hugetlb memslot alignment test mode

 arch/riscv/kvm/mmu.c                          | 54 +++++++++++++++----
 .../selftests/kvm/kvm_page_table_test.c       | 28 +++++++---
 2 files changed, 66 insertions(+), 16 deletions(-)

-- 
2.43.0