On 29/05/20 14:08, Vitaly Kuznetsov wrote:
>> On 24/04/20 13:37, Jon Doron wrote:
>>> +static int syndbg_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host)
>>> +{
>>> + struct kvm_hv_syndbg *syndbg = vcpu_to_hv_syndbg(vcpu);
>>> +
>>> + if (!syndbg->active && !host)
>>> + return 1;
>>> +
>> One small thing: is the ENABLE_CAP and active field needed? Can you
>> just check if the guest has the syndbg CPUID bits set?
>>
> Yes, we can probably get away with a static capability (so userspace
> knows that the interface is supported and CPUID bit can be set) and
> check guest_cpuid_has() here but we don't have Hyper-V feature leaves
> exposed as X86_FEATURE_* (yet). It is probably possible to implement an
> interim solution by open coding the check with kvm_find_cpuid_entry() or
> something like that.
Yes, that would be fine if you just abstract it in its own function.
Paolo
