On 21/02/2018 15:52, Tom Lendacky wrote:
> On 2/21/2018 8:47 AM, Tom Lendacky wrote:
>> On 2/21/2018 8:32 AM, Paolo Bonzini wrote:
>>> On 21/02/2018 15:15, Tom Lendacky wrote:
>>>> On 2/21/2018 5:41 AM, Paolo Bonzini wrote:
>>>>> On 16/02/2018 00:12, Tom Lendacky wrote:
>>>>>> +static u32 msr_based_features[] = {
>>>>>> +};
>>>>>> +
>>>>>> +static unsigned int num_msr_based_features = ARRAY_SIZE(msr_based_features);
>>>>>> +
>>>>>> bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer)
>>>>>> {
>>>>>> if (efer & efer_reserved_bits)
>>>>>> @@ -2785,6 +2794,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>>>>> case KVM_CAP_SET_BOOT_CPU_ID:
>>>>>> case KVM_CAP_SPLIT_IRQCHIP:
>>>>>> case KVM_CAP_IMMEDIATE_EXIT:
>>>>>> + case KVM_CAP_GET_MSR_FEATURES:
>>>>>> r = 1;
>>>>>> break;
>>>>>> case KVM_CAP_ADJUST_CLOCK:
>>>>>> @@ -4410,6 +4420,47 @@ long kvm_arch_vm_ioctl(struct file *filp,
>>>>>> r = kvm_x86_ops->mem_enc_unreg_region(kvm, ®ion);
>>>>>> break;
>>>>>> }
>>>>>> + case KVM_GET_MSR_INDEX_LIST: {
>>>>>> + struct kvm_msr_list __user *user_msr_list = argp;
>>>>>> + struct kvm_msr_list msr_list;
>>>>>> + unsigned int n;
>>>>>> +
>>>>>> + r = -EFAULT;
>>>>>> + if (copy_from_user(&msr_list, user_msr_list, sizeof(msr_list)))
>>>>>> + goto out;
>>>>>> + n = msr_list.nmsrs;
>>>>>> + msr_list.nmsrs = num_msr_based_features;
>>>>>> + if (copy_to_user(user_msr_list, &msr_list, sizeof(msr_list)))
>>>>>> + goto out;
>>>>>> + r = -E2BIG;
>>>>>> + if (n < msr_list.nmsrs)
>>>>>> + goto out;
>>>>>> + r = -EFAULT;
>>>>>> + if (copy_to_user(user_msr_list->indices, &msr_based_features,
>>>>>> + num_msr_based_features * sizeof(u32)))
>>>>>> + goto out;
>>>>>> + r = 0;
>>>>>> + break;
>>>>>
>>>>> I think it's better to have some logic in kvm_init_msr_list, to filter
>>>>> the MSR list based on whatever MSRs the backend provides.
>>>>
>>>> Ok, that's what I had originally and then you said to just return the full
>>>> list and let KVM_GET_MSR return a 0 or 1 if it was supported. I can switch
>>>> it back.
>>>
>>> Hmm, I cannot find this remark (I would have been very confused, so I
>>> tried to look for it). I commented on removing kvm_valid_msr_feature,
>>> but not kvm_init_msr_list.
>>
>> I think this is the reply that sent me off on that track:
>> https://marc.info/?l=linux-kernel&m=151862648123153&w=2
Yeah, it was referring to AMD hosts that don't have the MSR. Sorry for
the confusion.
>> I'll make it consistent with the other MSR-related items and initialize
>> the list in kvm_init_msr_list(). I'll change the signature of the
>> msr_feature() kvm_x86_ops callback to take an index and optionally return
>> a data value so it can be used to check for support when building the
>> list and return a value when needed.
>
> Hmm, actually I'll just leave the signature alone and pass in a local
> kvm_msr_entry struct variable for the call when initializing the list.
Sounds good!
Paolo
