On 30/01/12 22:46, Peter Maydell wrote:
> On 20 January 2012 02:59, Christoffer Dall
> <[email protected]> wrote:
>> There's a new list of issues available at:
>>
>> https://github.com/virtualopensystems/linux-kvm-arm/issues
>
> Thanks for putting this up. Here's a couple more for you :-)
>
> * Support guest kernels configured for LPAE
>
> At the moment (well, if you have Marc's 3.3rc1 tree with the A15 L2
> cache control register bodge in it) you can boot an A15 kernel
> configured without LPAE as a KVM guest, but an LPAE kernel with LPAE
> enabled will not boot. This probably mostly requires supporting the
> 64 bit wide cp15 registers that LPAE implies.
So I had a look at that one. LPAE is not the problem (an LPAE kernel
runs fine as a guest), but a KVM-enabled kernel dies trying to execute
an SMC instruction.
The obvious fix would be to test for the virt extensions in ID_PFR1
before enabling KVM, and mask out the virt extensions from the same
register in the guest by trapping CP15-c0. But c0 is used by cache
maintenance operations, and trapping would lead to unacceptable
performance degradation.
Ideas anyone?
M.
--
Jazz is not dead. It just smells funny...
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