On 15 April 2013 11:39, Andre Przywara <andre.przywara@xxxxxxxxxx> wrote:
I've run on this problem before, while trying to run KVM guests on A7 cores.
For some reason the 3rd A7 hangs in arch/arm/kvm/init.S, on the instruction that updates HSCTLR between the two isbs on __do_hyp_init (mcr p15, 4, r0, c1, c0, 0). If you boot the system with maxcpus=4 then init_hyp_mode() will not hang on the A7 cluster. Other than that from my limited testing KVM on A7 works on a usual linux guest. I also tried to only boot the 3rd A7 core to rule out any racing issues, but still the same behaviour applies.
Also good to note that last time I checked, once KVM initializes on all A15 and A7 cores, you can change the guest process between the two clusters and it seems to work without problems. Of course I only did a very limited testing of the setup, so take this with a grain of salt.
Regards.
> [Q: doesGood point. It seems like the code hangs in init_hyp_mode().
> all the hyp mode code have to also run on the A15s or
> is it A7-safe?]
Will do more debugging in there now.
I've run on this problem before, while trying to run KVM guests on A7 cores.
For some reason the 3rd A7 hangs in arch/arm/kvm/init.S, on the instruction that updates HSCTLR between the two isbs on __do_hyp_init (mcr p15, 4, r0, c1, c0, 0). If you boot the system with maxcpus=4 then init_hyp_mode() will not hang on the A7 cluster. Other than that from my limited testing KVM on A7 works on a usual linux guest. I also tried to only boot the 3rd A7 core to rule out any racing issues, but still the same behaviour applies.
Also good to note that last time I checked, once KVM initializes on all A15 and A7 cores, you can change the guest process between the two clusters and it seems to work without problems. Of course I only did a very limited testing of the setup, so take this with a grain of salt.
Regards.
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