linux-kernel - Re: [PATCH 4/7] KVM: TDX: Handle TDG.VP.VMCALL<MapGPA>

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Message-ID: <fc0306fe-8a78-4024-9b67-0f8cb9f7450a@linux.intel.com>
Date: Wed, 18 Dec 2024 09:38:10 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>
Cc: pbonzini@...hat.com, seanjc@...gle.com, kvm@...r.kernel.org,
 rick.p.edgecombe@...el.com, kai.huang@...el.com, adrian.hunter@...el.com,
 reinette.chatre@...el.com, tony.lindgren@...ux.intel.com,
 isaku.yamahata@...el.com, yan.y.zhao@...el.com, chao.gao@...el.com,
 michael.roth@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] KVM: TDX: Handle TDG.VP.VMCALL<MapGPA>




On 12/16/2024 2:03 PM, Xiaoyao Li wrote:
> On 12/16/2024 9:08 AM, Binbin Wu wrote:
>>
>>
>>
>> On 12/13/2024 5:32 PM, Xiaoyao Li wrote:
>>> On 12/1/2024 11:53 AM, Binbin Wu wrote:
>>>
>> [...]
>>>> +
>>>> +static int tdx_map_gpa(struct kvm_vcpu *vcpu)
>>>> +{
>>>> +    struct vcpu_tdx * tdx = to_tdx(vcpu);
>>>> +    u64 gpa = tdvmcall_a0_read(vcpu);
>>>
>>> We can use kvm_r12_read() directly, which is more intuitive. And we can drop the MACRO for a0/a1/a2/a3 accessors in patch 022.
>> I am neutral about it.
>>
>
> a0, a1, a2, a3, are the name convention for KVM's hypercall. It makes sense when serving as the parameters to __kvm_emulate_hypercall().
>
> However, now __kvm_emulate_hypercall() is made to a MACRO and we don't need the temp variable like a0 = kvm_xx_read().
>
> For TDVMCALL leafs other than normal KVM hypercalls, they are all TDX specific and defined in TDX GHCI spec, a0/a1/a2/a3 makes no sense for them.
OK, make sense.

Thanks!