linux-kernel - Re: [PATCH 2/7] KVM: TDX: Implement TDX vcpu enter/exit path

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Message-ID: <91eccab3-2740-4bb7-ac3f-35dea506a0de@linux.intel.com>
Date: Fri, 22 Nov 2024 13:56:10 +0800
From: Binbin Wu <binbin.wu@...ux.intel.com>
To: Xiaoyao Li <xiaoyao.li@...el.com>, Adrian Hunter
 <adrian.hunter@...el.com>, pbonzini@...hat.com, seanjc@...gle.com,
 kvm@...r.kernel.org, dave.hansen@...ux.intel.com
Cc: rick.p.edgecombe@...el.com, kai.huang@...el.com,
 reinette.chatre@...el.com, tony.lindgren@...ux.intel.com,
 dmatlack@...gle.com, isaku.yamahata@...el.com, nik.borisov@...e.com,
 linux-kernel@...r.kernel.org, x86@...nel.org, yan.y.zhao@...el.com,
 chao.gao@...el.com, weijiang.yang@...el.com
Subject: Re: [PATCH 2/7] KVM: TDX: Implement TDX vcpu enter/exit path




On 11/22/2024 1:23 PM, Xiaoyao Li wrote:
[...]
>> +
>> +fastpath_t tdx_vcpu_run(struct kvm_vcpu *vcpu, bool force_immediate_exit)
>> +{
>> +    struct vcpu_tdx *tdx = to_tdx(vcpu);
>> +
>> +    /* TDX exit handle takes care of this error case. */
>> +    if (unlikely(tdx->state != VCPU_TD_STATE_INITIALIZED)) {
>> +        /* Set to avoid collision with EXIT_REASON_EXCEPTION_NMI. */
>
> It seems the check fits better in tdx_vcpu_pre_run().

Indeed, it's cleaner to move the check to vcpu_pre_run.
Then no need to set the value to vp_enter_ret, and the comments are not
needed.

>
> And without the patch of how TDX handles Exit (i.e., how deal with vp_enter_ret), it's hard to review this comment.
>
>> +        tdx->vp_enter_ret = TDX_SW_ERROR;
>> +        return EXIT_FASTPATH_NONE;
>> +    }
>> +
>> +    trace_kvm_entry(vcpu, force_immediate_exit);
>> +
>> +    tdx_vcpu_enter_exit(vcpu);
>> +
>> +    vcpu->arch.regs_avail &= ~VMX_REGS_LAZY_LOAD_SET;
>> +    trace_kvm_exit(vcpu, KVM_ISA_VMX);
>> +
>> +    return EXIT_FASTPATH_NONE;
>> +}
>> +
[...]