linux-kernel - Re: [RFC PATCH v5 027/104] KVM: TDX: initialize VM with TDX specific parameters

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Message-ID: <6e370d39-fcb6-c158-e5fb-690cd3802150@redhat.com>
Date:   Tue, 5 Apr 2022 15:01:09 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Kai Huang <kai.huang@...el.com>, isaku.yamahata@...el.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 027/104] KVM: TDX: initialize VM with TDX specific
 parameters

On 3/31/22 06:55, Kai Huang wrote:
>>   
>> +struct kvm_tdx_init_vm {
>> +	__u32 max_vcpus;
>> +	__u32 tsc_khz;
>> +	__u64 attributes;
>> +	__u64 cpuid;
> Is it better to append all CPUIDs directly into this structure, perhaps at end
> of this structure, to make it more consistent with TD_PARAMS?
> 
> Also, I think somewhere in commit message or comments we should explain why
> CPUIDs are passed here (why existing KVM_SET_CUPID2 is not sufficient).
> 

Indeed, it would be easier to use the existing cpuid data in struct 
kvm_vcpu, because right now there is no way to ensure that they are 
consistent.

Why is KVM_SET_CPUID2 not enough?  Are there any modifications done by 
KVM that affect the measurement?

Thanks,

Paolo