[PATCH v5 0/5] KVM: riscv: Fix stale FWFT feature exposure and enhance selftests

[Yong-Xuan Wang]

This series fixes three bugs in the SBI FWFT (Firmware Features) extension
and improves the related selftest infrastructure.
The bugs are:
1. Missing CSR dirty marking: When userspace sets FWFT feature values via
   KVM_SET_ONE_REG, modified CSRs (e.g., henvcfg.PMM for pointer masking)
   are not marked dirty, leading to stale state after vCPU scheduling or
   migration.
2. Hardware probing side effects: The try_to_set_pmm() function modifies
   HENVCFG.PMM during hardware capability detection but fails to restore
   the original value, leaving the CSR in an altered state that affects
   subsequent operations.
3. Stale feature exposure: FWFT feature support is cached at vCPU
   initialization time. When userspace subsequently disables ISA extensions
   via KVM_SET_ONE_REG, the cached support status is not updated, allowing
   guests to access features that depend on disabled extensions.
Patches 1-3 fix these bugs separately.

The selftest improvements (patches 4-5) enhance the get-reg-list test by
refactoring the extension sublist infrastructure and splitting FWFT
feature testing into separate, properly-gated sublists.

---
Changes in v5:
- Add CSR dirty marking fix (new patch 1/5) (sashiko-bot)
- Split original FWFT bug fix into two focused patches
  - Add init() callback with try_to_set_pmm() restoration fix (new patch
    2/5) (sashiko-bot)
  - Keep runtime supported() checks as separate patch (patch 3/5)
- Link to v4: https://patch.msgid.link/20260601-kvm-get_reg_list-v2-v4-0-c88abc81ebda@sifive.com

Changes in v4:
- Rename the title of cover letter
- Disable preemption when running try_to_set_pmm() (sashiko-bot)
- Remove check_supported_reg() (sashiko-bot)
- Link to v3: https://patch.msgid.link/20260528-kvm-get_reg_list-v2-v3-0-170969a8599f@sifive.com

Changes in v3:
- Restore 'supported' field with init() callback for initialization probing
  (sashiko-bot)
- Add NULL checks before calling feature->supported() in all functions
- Fix isa_ext_enabled tracking logic and restore isa_ext_cant_disable array
- Add sbi_ext_enabled tracking and enhance dependency checking (sashiko-bot)
- Refine code organization and variable naming consistency (sashiko-bot)
- Link to v2: https://patch.msgid.link/20260526-kvm-get_reg_list-v2-v2-0-7940a401454a@sifive.com

Changes in v2:
- Fix FWFT stale feature exposure by removing static 'supported' field
- Refactor get-reg-list test to use unified extension sublist macros
- Split FWFT testing into per-feature sublists with runtime checks
  (Andrew)

To: Anup Patel <anup at brainfault.org>
To: Atish Patra <atish.patra at linux.dev>
To: Paul Walmsley <pjw at kernel.org>
To: Palmer Dabbelt <palmer at dabbelt.com>
To: Albert Ou <aou at eecs.berkeley.edu>
To: Alexandre Ghiti <alex at ghiti.fr>
To: Clément Léger <cleger at rivosinc.com>
To: Andrew Jones <ajones at ventanamicro.com>
To: Paolo Bonzini <pbonzini at redhat.com>
To: Shuah Khan <shuah at kernel.org>
Cc: greentime.hu at sifive.com
Cc: vincent.chen at sifive.com
Cc: zong.li at sifive.com
Cc: kvm at vger.kernel.org
Cc: kvm-riscv at lists.infradead.org
Cc: linux-riscv at lists.infradead.org
Cc: linux-kernel at vger.kernel.org
Cc: linux-kselftest at vger.kernel.org

---
Yong-Xuan Wang (5):
      KVM: RISC-V: SBI FWFT: Mark vCPU CSRs dirty after setting feature value
      KVM: RISC-V: SBI FWFT: Add optional init() callback for hardware probing
      KVM: RISC-V: SBI FWFT: Fix stale feature exposure after runtime extension changes
      KVM: riscv: selftests: Refactor ISA and SBI extension sublist macros
      KVM: riscv: selftests: Split SBI FWFT into separate feature-specific sublists

 arch/riscv/kvm/vcpu_sbi_fwft.c                   |  44 +++++++-
 tools/testing/selftests/kvm/riscv/get-reg-list.c | 138 ++++++++++++++---------
 2 files changed, 125 insertions(+), 57 deletions(-)
---
base-commit: c7832534a8160276cccb9a8cc8cafb5614c579d0
change-id: 20260526-kvm-get_reg_list-v2-f9f36961ac6c