linux-kernel - Re: [PATCH v19 105/130] KVM: TDX: handle KVM hypercall with TDG.VP.VMCALL

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Date: Wed, 17 Apr 2024 14:16:57 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Isaku Yamahata <isaku.yamahata@...el.com>, Chao Gao <chao.gao@...el.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
 isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com,
 isaku.yamahata@...ux.intel.com
Subject: Re: [PATCH v19 105/130] KVM: TDX: handle KVM hypercall with
 TDG.VP.VMCALL



On 4/4/2024 9:27 AM, Isaku Yamahata wrote:
> On Tue, Apr 02, 2024 at 04:52:46PM +0800,
> Chao Gao <chao.gao@...el.com> wrote:
>
>>> +static int tdx_emulate_vmcall(struct kvm_vcpu *vcpu)
>>> +{
>>> +	unsigned long nr, a0, a1, a2, a3, ret;
>>> +
>> do you need to emulate xen/hyper-v hypercalls here?
>
> No. kvm_emulate_hypercall() handles xen/hyper-v hypercalls,
> __kvm_emulate_hypercall() doesn't.
So for TDX, kvm doesn't support xen/hyper-v, right?

Then, should KVM_CAP_XEN_HVM and KVM_CAP_HYPERV be filtered out for TDX?

>
>> Nothing tells userspace that xen/hyper-v hypercalls are not supported and
>> so userspace may expose related CPUID leafs to TD guests.
>>