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

["Yang, Sheng" <sheng.yang@intel.com>]

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. 

-- 
Thanks
Yang, Sheng