On Tue, Aug 21, 2012 at 9:49 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: > On 21/08/12 12:47, Alexander Graf wrote: >> On 08/21/2012 01:39 PM, Marc Zyngier wrote: >>> On 20/08/12 21:45, Christoffer Dall wrote: >>>> On Mon, Aug 20, 2012 at 1:22 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >>>>> Guys, >>>>> >>>>> I'm seeing weird regressions on v11 when running Thumb2 code: >>>>> >>>>> [ 315.637769] cyclictest (3319): undefined instruction: pc=0000a2f4 >>>>> [ 315.637791] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>>> [ 316.216214] cyclictest (3324): undefined instruction: pc=0000a2f4 >>>>> [ 316.217515] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>>> [ 325.854063] cyclictest (3444): undefined instruction: pc=0000a2f4 >>>>> [ 325.854076] Code: 4640 4649 f002 fbc4 (ed95) 7b06 >>>>> >>>>> My previous work branch was quite solid (v10 based). Do we have a clear >>>>> idea of what's changed in the exception handling path? Or should I >>>>> consider doing the diff dance? >>>>> >>>>> I have the ugly feeling that we're adjusting the PC in a creative way. >>>>> >>>> if that's the case, it's probably the kvm_skip_instr() thingy. Which >>>> code are you running? simply a Thumb guest kernel or something in user >>>> space? If the latter, can you share? >>> This is a Thumb2 guest + userspace guest. The instruction is always the >>> same VFP instruction, so it actually looks VFP related, not PC adjusting >>> as I initially thought. Doing stuff on the host seems to easily trigger >>> the problem on the gust. >>> >>> But there's very little difference between my two trees (at least VFP >>> wise), hence my growing perplexity... >>> >>> I'll continue investigating. >> >> Did you maybe compile them with different config options? Like >> preemption? :) > > No, I'm quite careful to use the exact same config file. I also made > sure I was using 3.6-rc2 for both branches. I have a few additional ARM > specific patches that I'm going to back out, so the two trees are similar. > > Except for whatever comes from kvm/next, of course. But I can't see > anything there that would have such an weird impact. > I changed the allocation of the vfp_struct to support module loading/unloading. The vfp structs now get kmalloc'ed and memset (see init_hyp_mode). Maybe I messed something up there? -Christoffer _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
