[PATCH v3 0/7] Add support for FEAT_{LS64, LS64_V} and related tests

[Yicong Yang]

From: Yicong Yang <yangyicong at hisilicon.com>

Armv8.7 introduces single-copy atomic 64-byte loads and stores
instructions and its variants named under FEAT_{LS64, LS64_V}.
Add support for Armv8.7 FEAT_{LS64, LS64_V}:
- Add identifying and enabling in the cpufeature list
- Expose the support of these features to userspace through HWCAP3
  and cpuinfo
- Add related hwcap test
- Handle the trap of unsupported memory (normal/uncacheable) access in a VM

A real scenario for this feature is that the userspace driver can make use of
this to implement direct WQE (workqueue entry) - a mechanism to fill WQE
directly into the hardware.

Picked Marc's 2 patches form [1] for handling the LS64 trap in a VM on emulated
MMIO and the introduce of KVM_EXIT_ARM_LDST64B.

[1] https://lore.kernel.org/linux-arm-kernel/20240815125959.2097734-1-maz@kernel.org/

Tested with hwcap test [*]:
[*] https://lore.kernel.org/linux-arm-kernel/20250331094320.35226-5-yangyicong@huawei.com/
On host:
root at localhost:/tmp# dmesg | grep "All CPU(s) started"
[    0.504846] CPU: All CPU(s) started at EL2
root at localhost:/tmp# ./hwcap
[...]
# LS64 present
ok 217 cpuinfo_match_LS64
ok 218 sigill_LS64
ok 219 # SKIP sigbus_LS64
# LS64_V present
ok 220 cpuinfo_match_LS64_V
ok 221 sigill_LS64_V
ok 222 # SKIP sigbus_LS64_V
# 115 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:107 fail:0 xfail:0 xpass:0 skip:115 error:0

On guest:
root at localhost:/# dmesg | grep "All CPU(s) started"
[    0.451482] CPU: All CPU(s) started at EL1
root at localhost:/mnt# ./hwcap
[...]
# LS64 present
ok 217 cpuinfo_match_LS64
ok 218 sigill_LS64
ok 219 # SKIP sigbus_LS64
# LS64_V present
ok 220 cpuinfo_match_LS64_V
ok 221 sigill_LS64_V
ok 222 # SKIP sigbus_LS64_V
# 115 skipped test(s) detected. Consider enabling relevant config options to improve coverage.
# Totals: pass:107 fail:0 xfail:0 xpass:0 skip:115 error:0

Change since v2:
- Handle the LS64 fault to userspace and allow userspace to inject LS64 fault
- Reorder the patches to make KVM handling prior to feature support
Link: https://lore.kernel.org/linux-arm-kernel/20250331094320.35226-1-yangyicong@huawei.com/

Change since v1:
- Drop the support for LS64_ACCDATA
- handle the DABT of unsupported memory type after checking the memory attributes
Link: https://lore.kernel.org/linux-arm-kernel/20241202135504.14252-1-yangyicong@huawei.com/

Marc Zyngier (2):
  KVM: arm64: Add exit to userspace on {LD,ST}64B* outside of memslots
  KVM: arm64: Add documentation for KVM_EXIT_ARM_LDST64B

Yicong Yang (5):
  KVM: arm64: Handle DABT caused by LS64* instructions on unsupported
    memory
  KVM: arm/arm64: Allow user injection of unsupported exclusive/atomic
    DABT
  arm64: Provide basic EL2 setup for FEAT_{LS64, LS64_V} usage at EL0/1
  arm64: Add support for FEAT_{LS64, LS64_V}
  KVM: arm64: Enable FEAT_{LS64, LS64_V} in the supported guest

 Documentation/arch/arm64/booting.rst    | 12 ++++++
 Documentation/arch/arm64/elf_hwcaps.rst |  6 +++
 Documentation/virt/kvm/api.rst          | 43 +++++++++++++++++----
 arch/arm64/include/asm/el2_setup.h      | 12 +++++-
 arch/arm64/include/asm/esr.h            |  8 ++++
 arch/arm64/include/asm/hwcap.h          |  2 +
 arch/arm64/include/asm/kvm_emulate.h    |  7 ++++
 arch/arm64/include/uapi/asm/hwcap.h     |  2 +
 arch/arm64/include/uapi/asm/kvm.h       |  3 +-
 arch/arm64/kernel/cpufeature.c          | 51 +++++++++++++++++++++++++
 arch/arm64/kernel/cpuinfo.c             |  2 +
 arch/arm64/kvm/guest.c                  |  4 ++
 arch/arm64/kvm/inject_fault.c           | 29 ++++++++++++++
 arch/arm64/kvm/mmio.c                   | 27 ++++++++++++-
 arch/arm64/kvm/mmu.c                    | 21 +++++++++-
 arch/arm64/tools/cpucaps                |  2 +
 include/uapi/linux/kvm.h                |  3 +-
 17 files changed, 222 insertions(+), 12 deletions(-)

-- 
2.24.0