Found this when reviewing the PMU undef patches [1], which will get merged for 5.11 (Paolo accepted the pull request [2]). This only happens if we try to run the PMU tests when creating a VCPU *without* the PMU feature. I think qemu creates the VCPU by default with a PMU and I don't know if or how that could be disabled. On the other hand, kvmtool doesn't enable the feature by default, and you need the specify the --pmu knob on the command line to enable guest PMU. I think this should only affect kvmtool users. For reference, this is what happens without the patch when I try to run a PMU test on a host built from the kvmarm-5.11 tag from the pull request (the --pmu knob is missing from the kvmtool command line): $ lkvm run -c1 -m64 -f arm/pmu.flat -p cycle-counter # lkvm run --firmware arm/pmu.flat -m 64 -c 1 --name guest-821 Info: Placing fdt at 0x80200000 - 0x80210000 chr_testdev_init: chr-testdev: can't find a virtio-console Unhandled exception ec=0 (UNKNOWN) Vector: 4 (el1h_sync) ESR_EL1: 02000000, ec=0 (UNKNOWN) FAR_EL1: 1de7ec7edbadc0de (not valid) Exception frame registers: pc : [<000000008000b058>] lr : [<0000000080000084>] pstate: 00000000 sp : 000000008003ff60 x29: 0000000000000000 x28: 0000000000000000 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000002 x20: 0000000080016a10 x19: 0000000000000000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000080040000 x14: 0000000080040000 x13: 000000008003ff5c x12: 0000000000000058 x11: 0000000000000064 x10: 000000008003ff0c x9 : 0000000000008400 x8 : 0000000000008008 x7 : 0000000000000001 x6 : 0000000000000004 x5 : 0000000000000000 x4 : 0000000080050003 x3 : 0000000000000001 x2 : 0000000080016d38 x1 : 0000000080016a10 x0 : 0000000000000002 With the patch applied: $ lkvm run -c1 -m64 -f arm/pmu.flat -p cycle-counter # lkvm run --firmware arm/pmu.flat -m 64 -c 1 --name guest-1240 Info: Placing fdt at 0x80200000 - 0x80210000 chr_testdev_init: chr-testdev: can't find a virtio-console No PMU found, test skipped... SUMMARY: 0 tests [1] https://www.spinics.net/lists/kvm-arm/msg43347.html [2] https://www.spinics.net/lists/kvm/msg231080.html Alexandru Elisei (1): arm: pmu: Don't read PMCR if PMU is not present arm/pmu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) -- 2.29.2
