linux-kernel - Re: [RFC PATCH 06/13] KVM: SVM: Add logic to determine x2APIC mode

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Date:   Thu, 3 Mar 2022 09:12:01 +0700
From:   "Suthikulpanit, Suravee" <suravee.suthikulpanit@....com>
To:     Maxim Levitsky <mlevitsk@...hat.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     pbonzini@...hat.com, seanjc@...gle.com, joro@...tes.org,
        jon.grimm@....com, wei.huang2@....com, terry.bowman@....com
Subject: Re: [RFC PATCH 06/13] KVM: SVM: Add logic to determine x2APIC mode

Hi Maxim,

On 2/25/2022 12:29 AM, Maxim Levitsky wrote:
>> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
>> index 1a0bf6b853df..bfbebb933da2 100644
>> --- a/arch/x86/kvm/svm/svm.h
>> +++ b/arch/x86/kvm/svm/svm.h
>> @@ -225,6 +225,7 @@ struct vcpu_svm {
>>   	u32 dfr_reg;
>>   	struct page *avic_backing_page;
>>   	u64 *avic_physical_id_cache;
>> +	bool x2apic_enabled;
>>   
>>   	/*
>>   	 * Per-vcpu list of struct amd_svm_iommu_ir:
>> @@ -566,6 +567,7 @@ void avic_init_vmcb(struct vcpu_svm *svm);
>>   int avic_incomplete_ipi_interception(struct kvm_vcpu *vcpu);
>>   int avic_unaccelerated_access_interception(struct kvm_vcpu *vcpu);
>>   int avic_init_vcpu(struct vcpu_svm *svm);
>> +void avic_update_vapic_bar(struct vcpu_svm *svm, u64 data);
>>   void avic_vcpu_load(struct kvm_vcpu *vcpu, int cpu);
>>   void avic_vcpu_put(struct kvm_vcpu *vcpu);
>>   void avic_post_state_restore(struct kvm_vcpu *vcpu);
> 
> Have you looked at how this is done on Intel's APICv side?
> You need to implement .set_virtual_apic_mode instead.
> (look at vmx_set_virtual_apic_mode)

Actually, that would be better. I'll update this part to use svm_set_virtual_apic_mode,
which is doing nothing at the moment.

Regards,
Suravee