On Tue, 3 Mar 2020 at 21:32, Alexandru Elisei <alexandru.elisei@xxxxxxx> wrote:
>
> Hi,
>
> On 2/25/20 8:20 AM, Naresh Kamboju wrote:
> > Hi Alexandru,
> >
> > On Mon, 24 Feb 2020 at 23:14, Naresh Kamboju <naresh.kamboju@xxxxxxxxxx> wrote:
> >>> I think this is because you are running it on one physical CPU (it's exactly the
> >>> same message I am getting when I use taskset to run the tests). Can you try and
> >>> run it without taskset and see if it solves your issue?
> > We have a new problem when running [1] without taskset on Juno-r2.
> > None of the test got pass [2] when running without taskset on Juno-r2.
> >
> I think I have an explanation for why all the tests fail. qemu creates a vcpu to
> match the host cpu in kvm_arm_create_scratch_host_vcpu and it sets the target to
> whatever the result of the KVM_ARM_PREFERRED_TARGET ioctl is. If it's run on the
> little core, the target will be KVM_ARM_TARGET_CORTEX_A53. If it's run on the big
> core, the target will be KVM_ARM_TARGET_GENERIC_V8. I tried it a few times, and
> for me it has always been the big core.
>
> The vcpu is created from a different thread by doing a KVM_ARM_VCPU_INIT ioctl and
> KVM makes sure that the vcpu target matches the target corresponding to the
> physical CPU the thread is running on. What is happening is that the vcpu thread
> is run on a little core, so the target as far as KVM is concerned should be
> KVM_ARM_TARGET_CORTEX_A53, but qemu (correctly) set it to
> KVM_ARM_TARGET_GENERIC_V8. The ioctl return -EINVAL (-22) and qemu dies.
>
> To get around this, I ran the tests either only on the big cores or on the little
> cores.
Thanks for explaining in details.
I have seen this scenario and defined my test to run only on CPU 0.
The CPU 0 on my Juno-r2 devices found to be LITTLE CPU.
>
> I also managed to reliably trigger the PMU failures that you are seeing. They only
> happen when kvm-unit-tests is run on the little cores (ran them 10 times in a
> loop). When run on the big cores, everything is fine (also ran them 10 times in a
> loop). Log output when it fails:
Thanks for reproducing this PMU failure.
>
> # taskset -c 0,3,4,5 arm/run arm/pmu.flat
CPU 0,3,4,5 are seem to be on little cores.
> /usr/bin/qemu-system-aarch64 -nodefaults -machine virt,gic-version=host,accel=kvm
> -cpu host -device virtio-serial-device -device virtconsole,chardev=ctd -chardev
> testdev,id=ctd -device pci-testdev -display none -serial stdio -kernel
> arm/pmu.flat # -initrd /tmp/tmp.s4ld4DX4uK
> INFO: PMU version: 3
> INFO: pmu: PMU implementer/ID code/counters: 0x41("A")/0x3/6
> PASS: pmu: Control register
> Read 0 then 0.
> FAIL: pmu: Monotonically increasing cycle count
> instrs : cycles0 cycles1 ...
> 4: 0
> cycles not incrementing!
> FAIL: pmu: Cycle/instruction ratio
> SUMMARY: 3 tests, 2 unexpected failures
>
> I'm looking into it.
- Naresh
