From: Yicong Yang <yangyicong@xxxxxxxxxxxxx>
Armv8.7 introduces single-copy atomic 64-byte loads and stores
instructions and its variants named under FEAT_{LS64, LS64_V,
LS64_ACCDATA}. Add support for Armv8.7 FEAT_{LS64, LS64_V, LS64_ACCDATA}:
- 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 depends on Marc's patchset[1] for enabling related
features in a VM, HCRX trap handling, etc.
[1] https://lore.kernel.org/linux-arm-kernel/20240815125959.2097734-1-maz@xxxxxxxxxx/
Tested with updated hwcap test:
On host:
root@localhost:/# dmesg | grep "All CPU(s) started"
[ 1.600263] CPU: All CPU(s) started at EL2
root@localhost:/# ./hwcap
[snip...]
# LS64 present
ok 169 cpuinfo_match_LS64
ok 170 sigill_LS64
ok 171 # SKIP sigbus_LS64
# LS64_V present
ok 172 cpuinfo_match_LS64_V
ok 173 sigill_LS64_V
ok 174 # SKIP sigbus_LS64_V
# LS64_ACCDATA present
ok 175 cpuinfo_match_LS64_ACCDATA
ok 176 sigill_LS64_ACCDATA
ok 177 # SKIP sigbus_LS64_ACCDATA
# Totals: pass:92 fail:0 xfail:0 xpass:0 skip:85 error:0
On guest:
root@localhost:/# dmesg | grep "All CPU(s) started"
[ 1.375272] CPU: All CPU(s) started at EL1
root@localhost:/# ./hwcap
[snip...]
# LS64 present
ok 169 cpuinfo_match_LS64
ok 170 sigill_LS64
ok 171 # SKIP sigbus_LS64
# LS64_V present
ok 172 cpuinfo_match_LS64_V
ok 173 sigill_LS64_V
ok 174 # SKIP sigbus_LS64_V
# LS64_ACCDATA present
ok 175 cpuinfo_match_LS64_ACCDATA
ok 176 sigill_LS64_ACCDATA
ok 177 # SKIP sigbus_LS64_ACCDATA
# Totals: pass:92 fail:0 xfail:0 xpass:0 skip:85 error:0
Yicong Yang (5):
arm64: Provide basic EL2 setup for FEAT_{LS64, LS64_V, LS64_ACCDATA}
usage at EL0/1
arm64: Add support for FEAT_{LS64, LS64_V, LS64_ACCDATA}
kselftest/arm64: Add HWCAP test for FEAT_{LS64, LS64_V, LS64_ACCDATA}
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 | 28 +++++
Documentation/arch/arm64/elf_hwcaps.rst | 9 ++
arch/arm64/include/asm/el2_setup.h | 26 ++++-
arch/arm64/include/asm/esr.h | 8 ++
arch/arm64/include/asm/hwcap.h | 3 +
arch/arm64/include/uapi/asm/hwcap.h | 3 +
arch/arm64/kernel/cpufeature.c | 70 +++++++++++-
arch/arm64/kernel/cpuinfo.c | 3 +
arch/arm64/kvm/mmu.c | 14 +++
arch/arm64/tools/cpucaps | 3 +
tools/testing/selftests/arm64/abi/hwcap.c | 127 ++++++++++++++++++++++
11 files changed, 291 insertions(+), 3 deletions(-)
--
2.24.0
