[PATCH] KVM: ARM: ignore guest L2 cache control SMCs on Highbank and OMAP

[Marc Zyngier]

On 2013-08-14 11:22, Peter Maydell wrote:
> On 14 August 2013 10:32, Marc Zyngier <marc.zyngier at arm.com> wrote:
>> On 2013-08-14 10:22, Andre Przywara wrote:
>
>>> +static int kvm_ignore_l2x0_call(struct kvm_vcpu *vcpu)
>>> +{
>>> +     unsigned long fn_nr = *vcpu_reg(vcpu, 12) & ~((u32) 0);
>>> +
>>> +     if (fn_nr == 0x102) {
>>> +             kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
>>> +             return 1;
>>> +     }
>>> +
>>> +     return 0;
>>> +}
>>
>> And what if I run mach-foo which uses r12 to request bar services 
>> from
>> secure mode? Is it safe to ignore it? We need something much better 
>> than
>> just testing random registers to guess what the guest wants.
>
> Definitely. This needs to be addressed via the kernel providing
> some mechanism so that userspace and/or a KVM-specific bit
> of 'firmware' running in the guest VM can handle the SMC
> calls the guest tries to make, because it's totally board
> specific.

Right. We're in violent agreement here.

What I can imagine is some kind of feature bit that would cause an exit 
all the way to userspace, letting QEMU handle the call.

That would be simple enough to implement, I believe. At least on the 
kernel side.

         M.
-- 
Fast, cheap, reliable. Pick two.