Re: [PATCH] KVM: VMX: Add ept_sync_context in flush_tlb

[Avi Kivity <avi@qumranet.com>]

Yang, Sheng wrote:
> On Wednesday 25 June 2008 20:02:17 Avi Kivity wrote:
>   
>> Yang, Sheng wrote:
>>     
>>> From 54dc26e44f1c0aa460bef409b799f36dae56a911 Mon Sep 17 00:00:00 2001
>>> From: Sheng Yang <sheng.yang@intel.com>
>>> Date: Wed, 18 Jun 2008 11:23:13 +0800
>>> Subject: [PATCH] KVM: VMX: Add ept_sync_context in flush_tlb
>>>
>>> Fix a potention issue caused by kvm_mmu_slot_remove_write_access().
>>> The old behavior don't sync EPT TLB with modified EPT entry, which
>>> result in inconsistent content of EPT TLB and EPT table.
>>>
>>>
>>> @@ -1407,6 +1408,8 @@ static void exit_lmode(struct kvm_vcpu *vcpu)
>>>  static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
>>>  {
>>>  	vpid_sync_vcpu_all(to_vmx(vcpu));
>>> +	if (vm_need_ept())
>>> +		ept_sync_context(to_vmx(vcpu));
>>>  }
>>>       
>> So we're flushing both the vpid tlb and the ept context?  What does an
>> ept context flush mean exactly?  tlb entries for gpa->hpa?
>>     
>
> Yeah, the entries for gpa->hpa. So if we don't do this, cpu may see rw entry 
> rather than ro, then write to it directly rather than fall into KVM. 
>
>   

I see.  Back to the patch, can't you replace vmx->eptp by 
construct_eptp(vcpu->arch.mmu.root_hpa)?

-- 
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