Re: [PATCH] KVM: nVMX: Reset vmxon_ptr upon VMXOFF emulation.

[Yu Zhang]

On Thu, Sep 09, 2021 at 04:20:35PM +0000, Sean Christopherson wrote:
> On Thu, Sep 09, 2021, Yu Zhang wrote:
> > From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> > 
> > Currently, 'vmx->nested.vmxon_ptr' is not reset upon VMXOFF
> > emulation. This is not a problem per se as we never access
> > it when !vmx->nested.vmxon. But this should be done to avoid
> > any issue in the future.
> > 
> > Also, initialize the vmxon_ptr when vcpu is created.
> > 
> > Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> > Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
> > ---
> >  arch/x86/kvm/vmx/nested.c | 1 +
> >  arch/x86/kvm/vmx/vmx.c    | 1 +
> >  2 files changed, 2 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> > index 90f34f12f883..e4260f67caac 100644
> > --- a/arch/x86/kvm/vmx/nested.c
> > +++ b/arch/x86/kvm/vmx/nested.c
> > @@ -289,6 +289,7 @@ static void free_nested(struct kvm_vcpu *vcpu)
> >  	kvm_clear_request(KVM_REQ_GET_NESTED_STATE_PAGES, vcpu);
> >  
> >  	vmx->nested.vmxon = false;
> > +	vmx->nested.vmxon_ptr = -1ull;
> 
> Looks like the "-1ull" comes from current_vmptr and friends, but using INVALID_GPA
> is more appropriate.  It's the same value, but less arbitrary.  The other usage of
> -1ull for guest physical addresses should really be cleaned up, too.
> 

Indeed. I guess many "-1ull"s will be replaced in nested.c.

We need another cleanup patch for this cleanup patch, which comes from my
first cleanup patch to just clean some comments.. :-) Anyway, thanks!

B.R.
Yu