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(-)
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@brainfault.org>
To: Atish Patra <atish.patra@linux.dev>
To: Paul Walmsley <pjw@kernel.org>
To: Palmer Dabbelt <palmer@dabbelt.com>
To: Albert Ou <aou@eecs.berkeley.edu>
To: Alexandre Ghiti <alex@ghiti.fr>
To: Clément Léger <cleger@rivosinc.com>
To: Andrew Jones <ajones@ventanamicro.com>
To: Paolo Bonzini <pbonzini@redhat.com>
To: Shuah Khan <shuah@kernel.org>
Cc: greentime.hu@sifive.com
Cc: vincent.chen@sifive.com
Cc: zong.li@sifive.com
Cc: kvm@vger.kernel.org
Cc: kvm-riscv@lists.infradead.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-kselftest@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
On Mon, Jun 1, 2026 at 3:56 PM Yong-Xuan Wang <yongxuan.wang@sifive.com> wrote: > > 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@brainfault.org> > To: Atish Patra <atish.patra@linux.dev> > To: Paul Walmsley <pjw@kernel.org> > To: Palmer Dabbelt <palmer@dabbelt.com> > To: Albert Ou <aou@eecs.berkeley.edu> > To: Alexandre Ghiti <alex@ghiti.fr> > To: Clément Léger <cleger@rivosinc.com> > To: Andrew Jones <ajones@ventanamicro.com> > To: Paolo Bonzini <pbonzini@redhat.com> > To: Shuah Khan <shuah@kernel.org> > Cc: greentime.hu@sifive.com > Cc: vincent.chen@sifive.com > Cc: zong.li@sifive.com > Cc: kvm@vger.kernel.org > Cc: kvm-riscv@lists.infradead.org > Cc: linux-riscv@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-kselftest@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 Queued this series for Linux-7.2 Regards, Anup
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