linux-kernel - Re: [PATCH v5 18/19] KVM:nVMX: Refine error code injection to nested VM

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Date:   Wed, 9 Aug 2023 11:00:38 +0800
From:   "Yang, Weijiang" <weijiang.yang@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
CC:     <pbonzini@...hat.com>, <peterz@...radead.org>,
        <john.allen@....com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <rick.p.edgecombe@...el.com>,
        <chao.gao@...el.com>, <binbin.wu@...ux.intel.com>
Subject: Re: [PATCH v5 18/19] KVM:nVMX: Refine error code injection to nested
 VM

On 8/5/2023 5:38 AM, Sean Christopherson wrote:
> This is not "refinement", this is full on supporting a new nVMX feature.  Please
> phrase the shortlog accordingly, e.g. something like this (it's not very good,
> but it's a start).
>
>    KVM: nVMX: Add support for exposing "No PM H/W error code checks" to L1
>
> Regarding shortlog, please update all of them in this series to put a space after
> the colon, i.e. "KVM: VMX:" and "KVM: x86:", not "KVM:x86:".
OK, will update this part.
>>   static void nested_vmx_setup_cr_fixed(struct nested_vmx_msrs *msrs)
>> diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
>> index 96952263b029..1884628294e4 100644
>> --- a/arch/x86/kvm/vmx/nested.h
>> +++ b/arch/x86/kvm/vmx/nested.h
>> @@ -284,6 +284,13 @@ static inline bool nested_cr4_valid(struct kvm_vcpu *vcpu, unsigned long val)
>>   	       __kvm_is_valid_cr4(vcpu, val);
>>   }
>>   
>> +static inline bool nested_cpu_has_no_hw_errcode(struct kvm_vcpu *vcpu)
>> +{
>> +	struct vcpu_vmx *vmx = to_vmx(vcpu);
>> +
>> +	return vmx->nested.msrs.basic & VMX_BASIC_NO_HW_ERROR_CODE;
> The "CC" part of my suggestion is critical to this being sane.  As is, this reads
> "nested CPU has no hardware error code", which is not even remotely close to the
> truth.
Understood, I was not aware of the essence of "CC".
> static inline bool nested_cpu_has_no_hw_errcode_cc(struct kvm_vcpu *vcpu)
> {
> 	return to_vmx(vcpu)->nested.msrs.basic & VMX_BASIC_NO_HW_ERROR_CODE_CC;
> }
>
> [*] https://lore.kernel.org/all/ZJ7vyBw1nbTBOfuf@google.com