linux-kernel - Re: [PATCH] KVM: Fix some obsolete comments

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Message-ID: <3e25a121a6754020ac3a1eda9fb7fad6@huawei.com>
Date:   Wed, 26 Feb 2020 01:48:28 +0000
From:   linmiaohe <linmiaohe@...wei.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
CC:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "sean.j.christopherson@...el.com" <sean.j.christopherson@...el.com>,
        "wanpengli@...cent.com" <wanpengli@...cent.com>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "joro@...tes.org" <joro@...tes.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "bp@...en8.de" <bp@...en8.de>, "hpa@...or.com" <hpa@...or.com>
Subject: Re: [PATCH] KVM: Fix some obsolete comments

Vitaly Kuznetsov <vkuznets@...hat.com> writes:
>linmiaohe <linmiaohe@...wei.com> writes:
>
>> From: Miaohe Lin <linmiaohe@...wei.com>
>>
>
>Thank you for the cleanup, I looked at nested_svm_intercept() and I see room for improvement, e.g. (completely untested!)
>
>diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 76c24b3491f6..fcb26d64d3c7 100644
>--- a/arch/x86/kvm/svm.c
>+++ b/arch/x86/kvm/svm.c
>@@ -3280,42 +3280,36 @@ static int nested_svm_intercept(struct vcpu_svm *svm)
>        case SVM_EXIT_IOIO:
>                vmexit = nested_svm_intercept_ioio(svm);
>                break;
>-       case SVM_EXIT_READ_CR0 ... SVM_EXIT_WRITE_CR8: {
>-               u32 bit = 1U << (exit_code - SVM_EXIT_READ_CR0);
>-               if (svm->nested.intercept_cr & bit)
>+       case SVM_EXIT_READ_CR0 ... SVM_EXIT_WRITE_CR8:
>+               if (svm->nested.intercept_cr &
>+                   BIT(exit_code - SVM_EXIT_READ_CR0))
>-       default: {
>-               u64 exit_bits = 1ULL << (exit_code - SVM_EXIT_INTR);
>-               if (svm->nested.intercept & exit_bits)
>+       default:
>+               if (svm->nested.intercept & BIT_ULL(exit_code - 
>+ SVM_EXIT_INTR))
>                        vmexit = NESTED_EXIT_DONE;
>        }
>-       }
> 
>        return vmexit;
> }
>
>Feel free to pick stuff you like and split your changes to this function in a separate patch.

Sounds good, many thanks for your improvement suggestion. Will do in a separate patch.

>>  	u32 exit_code = svm->vmcb->control.exit_code; diff --git 
>> throws
>> - * #UD or #GP.
>> + * #UD, #GP or #SS.
>
>Oxford comma, anyone? :-)))

I have no strong preference. ^_^

>>   */
>>  int get_vmx_mem_address(struct kvm_vcpu *vcpu, unsigned long exit_qualification,
>
>All your changes look correct, so
>
>Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
>

Many thanks for your review, and nice suggestion again!