Re: [PATCH 1/2] KVM: introduce __vmx_flush_tlb to handle specific vpid

[Wanpeng Li]

On 9/25/15 12:12 AM, Bandan Das wrote:
> Wanpeng Li <wanpeng.li@xxxxxxxxxxx> writes:
>
> > Introduce __vmx_flush_tlb() to handle specific vpid.
> >
> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
> > ---
> >   arch/x86/kvm/vmx.c | 21 +++++++++++++--------
> >   1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> > index 794c529..7188c5e 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -1343,13 +1343,13 @@ static void loaded_vmcs_clear(struct loaded_vmcs *loaded_vmcs)
> >   			 __loaded_vmcs_clear, loaded_vmcs, 1);
> >   }
> >   
> > -static inline void vpid_sync_vcpu_single(struct vcpu_vmx *vmx)
> > +static inline void vpid_sync_vcpu_single(int vpid)
> >   {
> > -	if (vmx->vpid == 0)
> > +	if (vpid == 0)
> >   		return;
> >   
> >   	if (cpu_has_vmx_invvpid_single())
> > -		__invvpid(VMX_VPID_EXTENT_SINGLE_CONTEXT, vmx->vpid, 0);
> > +		__invvpid(VMX_VPID_EXTENT_SINGLE_CONTEXT, vpid, 0);
> >   }
> >   
> >   static inline void vpid_sync_vcpu_global(void)
> > @@ -1358,10 +1358,10 @@ static inline void vpid_sync_vcpu_global(void)
> >   		__invvpid(VMX_VPID_EXTENT_ALL_CONTEXT, 0, 0);
> >   }
> >   
> > -static inline void vpid_sync_context(struct vcpu_vmx *vmx)
> > +static inline void vpid_sync_context(int vpid)
> >   {
> >   	if (cpu_has_vmx_invvpid_single())
> > -		vpid_sync_vcpu_single(vmx);
> > +		vpid_sync_vcpu_single(vpid);
> >   	else
> >   		vpid_sync_vcpu_global();
> >   }
> Not sure myself what's the right thing to do but this may be undesirable
> in a nested environment. Assuming the processor supports global invalidation
> only, this seems like a easy way for the nested guest to invalidate *all*
> mappings - even the L1 specific mappings.

Indeed, however, there's no easy way to handle the w/o single 
invalidation case, we can improve it if you have any idea, otherwise, it 
can be left to further optimization. :-)

Regards,
Wanpeng Li
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