Presently we don't have any automatic stress testing for the handling of floating point save and restore with KVM, nor it's interaction with the host's management of the floating point registers. The majority of the focused stress testing has been done by running the existing fp-stress selftest on the host, starting a guest and then running fp-stress in there too but this has been a manual process rather than something done as a matter of routine by CI.
Plug this gap by reworking the test loads so that they can be run as KVM guests, using a simple VMM that provides the interface that fp-stress expects from it's test loads. We run the FPSIMD and SVE tests in KVM guests for half the CPUs, if EL2 is available then half the KVM tests will use it. The tests run in a minimal environment with the VMM and test binaries tightly coupled to each other. There's more coverage could be added, but this is an improvement over the current situation and can be built on in future. Off the top of my head: - We only test nested guests running at EL2 with E2H set. - We only run the guests at the highest VL they support. - Enabling the MMU would avoid surprises due to the performance differences. - We do not run any protected guests (this currently taints the kernel so should wait until the pKVM support is less experimental). - It might be useful to have the VMM signal handler save and restore the guest register state to exercise that path. - Possibly it would be useful to disable irrelevant features so less time is spent context switching non-FP state? Signed-off-by: Mark Brown <[email protected]> --- Mark Brown (11): kselftest/arm64: Factor Linux syscalls out of asm-utils.S kselftest/arm64: Factor shared signal handlers out of fp-stress loads kselftest/arm64: Move exit calls out of fp-stress loads kselftest/arm64: Use exit_error() rather than SIGABRT in fp-stress kselftest/arm64: Exit with an error code on data mismatches in fp-stress kselftest/arm64: Factor startup code out of fp-stress load programs kselftest/arm64: Remove the sched_yield()s from the fp-stress loads kselftest/arm64: Add a very simple VMM for use in fp-stress kselftest/arm64: Build KVM guest versions of the fp-stress loads kselftest/arm64: Use execv() to start fp-stress test loads kselftest/arm64: Run KVM guests from fp-stress tools/testing/selftests/arm64/fp/.gitignore | 4 + tools/testing/selftests/arm64/fp/Makefile | 64 ++- tools/testing/selftests/arm64/fp/asm-utils-kvm.S | 86 +++ tools/testing/selftests/arm64/fp/asm-utils-linux.S | 181 +++++++ tools/testing/selftests/arm64/fp/asm-utils.S | 36 -- tools/testing/selftests/arm64/fp/fp-pidbench.S | 6 +- .../testing/selftests/arm64/fp/fp-stress-kvm.lds.S | 58 ++ tools/testing/selftests/arm64/fp/fp-stress-vmm.c | 596 +++++++++++++++++++++ tools/testing/selftests/arm64/fp/fp-stress-vmm.h | 17 + tools/testing/selftests/arm64/fp/fp-stress.c | 230 +++++++- tools/testing/selftests/arm64/fp/fpsimd-test.S | 121 +---- tools/testing/selftests/arm64/fp/sve-test.S | 139 +---- tools/testing/selftests/arm64/fp/za-test.S | 138 +---- tools/testing/selftests/arm64/fp/zt-test.S | 131 +---- 14 files changed, 1244 insertions(+), 563 deletions(-) --- base-commit: cee9395acd8043be0644b25c34bfa86623f2b935 change-id: 20250401-arm64-fp-stress-kvm-4720ca307da4 Best regards, -- Mark Brown <[email protected]>
