On 30/01/12 22:46, Peter Maydell wrote: > On 20 January 2012 02:59, Christoffer Dall > <c.dall@xxxxxxxxxxxxxxxxxxxxxx> 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... -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
