[PATCH] ARM: KVM: iterate over all CPUs for CPU compatibility check

[Christoffer Dall]

On Tue, Apr 16, 2013 at 8:59 AM, Christoffer Dall <cdall at cs.columbia.edu> wrote:
> On Mon, Apr 15, 2013 at 2:52 AM, Alexander Spyridakis
> <a.spyridakis at virtualopensystems.com> wrote:
>> On 15 April 2013 11:39, Andre Przywara <andre.przywara at linaro.org> wrote:
>>>
>>> > [Q: does
>>> >     all the hyp mode code have to also run on the A15s or
>>> >     is it A7-safe?]
>>>
>>> Good point. It seems like the code hangs in init_hyp_mode().
>>> 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.
>>
> You lost me on the maxcpus=4 and racing point here. If it works with
> maxcpus=4 then it works with two A7s, right? Why would running with
> maxcpus=3 (ie. one A7) rule out any race condition?
>
[resending this as someone misspelled Marc's e-mail]