From: Yicong Yang <yangyic...@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.
This patchset also complement with Marc's patchset v2[1] for handling LS64*
trapped if not advertised for a VM.
[1]
https://lore.kernel.org/linux-arm-kernel/20250310122505.2857610-1-...@kernel.org/
Tested with updated hwcap test:
On host:
root@localhost:/tmp# dmesg | grep "All CPU(s) started"
[ 0.504846] CPU: All CPU(s) started at EL2
root@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@localhost:/# dmesg | grep "All CPU(s) started"
[ 0.205580] CPU: All CPU(s) started at EL1
root@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 v1:
- Drop the suppport 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-yangyic...@huawei.com/
Yicong Yang (6):
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
kselftest/arm64: Add HWCAP test for FEAT_{LS64, LS64_V}
arm64: Add ESR.DFSC definition of unsupported exclusive or atomic
access
KVM: arm64: Handle DABT caused by LS64* instructions on unsupported
memory
Documentation/arch/arm64/booting.rst | 12 +++
Documentation/arch/arm64/elf_hwcaps.rst | 6 ++
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/kernel/cpufeature.c | 51 +++++++++++++
arch/arm64/kernel/cpuinfo.c | 2 +
arch/arm64/kvm/inject_fault.c | 35 +++++++++
arch/arm64/kvm/mmu.c | 37 +++++++++-
arch/arm64/tools/cpucaps | 2 +
tools/testing/selftests/arm64/abi/hwcap.c | 90 +++++++++++++++++++++++
13 files changed, 264 insertions(+), 2 deletions(-)
--
2.24.0
