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SubjectRe: [RFC PATCH 1/2] KVM: x86: Add a framework for supporting MSR-based features
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On 2/13/2018 10:25 AM, Paolo Bonzini wrote:
> On 08/02/2018 23:58, Tom Lendacky wrote:
>> +bool kvm_valid_msr_feature(u32 msr, u64 data)
>> +{
>> + unsigned int i;
>> +
>> + for (i = 0; i < num_msr_based_features; i++) {
>> + struct kvm_msr_based_features *m = msr_based_features + i;
>> +
>> + if (msr != m->msr)
>> + continue;
>> +
>> + /* Make sure not trying to change unsupported bits */
>> + return (data & ~m->mask) ? false : true;
>> + }
>> +
>> + return false;
>> +}
>> +EXPORT_SYMBOL_GPL(kvm_valid_msr_feature);
>> +
>
> This is probably unnecessary too (the allowed values are a bit more
> complicated for, you just guessed it, VMX capability MSRs) and you can
> just check bits other than LFENCE in svm_set_msr.

The whole routine or just the bit checking? I can see still needing the
check to be sure the "feature" is present.

Thanks,
Tom

>
> Paolo
>

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