Re: [RFC PATCH 1/2] KVM: x86: Add a framework for supporting MSR-based features

[Paolo Bonzini]

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.

Paolo