Some of the ARMv7 & ARMv8 load/store instructions might trigger a data abort exception with no valid ISS info to be decoded. The lack of decode info makes it at least tricky to emulate the instruction which is one of the (many) reasons why KVM will not even try to do so.
So far, if a guest made an attempt to access memory outside the memory slot, KVM reported vague ENOSYS. As a result QEMU exited with no useful information being provided or even a clue on what has just happened. Recently ARM KVM introduced support for notifying guest of an attempt to execute an instruction that resulted in dabt with no valid ISS decoding info. This still leaves QEMU to handle the case, but at least now, it can enable further debugging of the encountered issue by being more verbose in a (hopefully) useful way. Beata Michalska (1): target/arm: kvm: Handle DABT with no valid ISS accel/kvm/kvm-all.c | 15 +++++++ accel/stubs/kvm-stub.c | 4 ++ include/sysemu/kvm.h | 1 + target/arm/cpu.h | 3 +- target/arm/kvm.c | 95 ++++++++++++++++++++++++++++++++++++++++++ target/arm/kvm32.c | 3 ++ target/arm/kvm64.c | 3 ++ target/arm/kvm_arm.h | 19 +++++++++ 8 files changed, 142 insertions(+), 1 deletion(-) -- 2.17.1
