Re: [RFC Patch 3/3] KVM/x86: Add tlb_remote_flush callback support for vmcs
From: Vitaly Kuznetsov
Date: Thu Jun 14 2018 - 06:34:03 EST
Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> writes:
> On 6/12/2018 11:12 PM, Vitaly Kuznetsov wrote:
>> Tianyu Lan <Tianyu.Lan@xxxxxxxxxxxxx> writes:
>>> +static int vmx_remote_flush_tlb(struct kvm *kvm)
>>> + struct kvm_vcpu *vcpu = kvm_get_vcpu(kvm, 0);
>>> + if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
>>> + return -1;
>> Why vcpu0? Can arch.mmu.root_hpa-s differ across vCPUs? What happens if
>> they do?
> Yes, it may take place that arch.mmu.root_hpa is differ across vCPUs.
> We may check all vcpu root_hpa and use the hypercall when there is only
> one validated ept table. If not, go back to current way.
I'd suggest an optimization: keep track of wether root_hpas are equal
across all vcpus (check this on change).