Re: [PATCH] KVM: SVM: Fix potential wrong physical id in avic_handle_ldr_update

[linmiaohe]

Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> writes:

>> Guest physical APIC ID may not equal to vcpu->vcpu_id in some case.
>> We may set the wrong physical id in avic_handle_ldr_update as we 
>> always use vcpu->vcpu_id.

Hi, Vitaly, thanks for your reply.
Do you think there may be a wrong physical id in avic_handle_ldr_update too ?

>>
>> @@ -4591,6 +4591,8 @@ static int avic_handle_ldr_update(struct kvm_vcpu *vcpu)
>>  	int ret = 0;
>>  	struct vcpu_svm *svm = to_svm(vcpu);
>>  	u32 ldr = kvm_lapic_get_reg(vcpu->arch.apic, APIC_LDR);
>> +	u32 apic_id_reg = kvm_lapic_get_reg(vcpu->arch.apic, APIC_ID);
>> +	u32 id = (apic_id_reg >> 24) & 0xff;
>
>If we reach here than we're guaranteed to be in xAPIC mode, right? Could you maybe export and use kvm_xapic_id() here then (and in
>avic_handle_apic_id_update() too)?
>

I think we're guaranteed to be in xAPIC mode when we reach here. I would have a try to export
and use use kvm_xapic_id here and in avic_handle_apic_id_update too.
Thanks for your suggestion.

Have a nice day.
Best wishes.