Re: [Xen-devel] [RFC v1 14/15] Suppress posting interrupts when 'SN' is set

["Wu, Feng" <feng.wu@xxxxxxxxx>]

> -----Original Message-----
> From: Andrew Cooper [mailto:andrew.cooper3@xxxxxxxxxx]
> Sent: Friday, March 27, 2015 4:35 AM
> To: Wu, Feng; xen-devel@xxxxxxxxxxxxx
> Cc: Zhang, Yang Z; Tian, Kevin; keir@xxxxxxx; JBeulich@xxxxxxxx
> Subject: Re: [Xen-devel] [RFC v1 14/15] Suppress posting interrupts when 'SN' 
> is
> set
> 
> On 25/03/15 12:31, Feng Wu wrote:
> > Currently, we don't support urgent interrupt, all interrupts
> > are recognized as non-urgent interrupt, so we cannot send
> > posted-interrupt when 'SN' is set.
> >
> > Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> > ---
> >   xen/arch/x86/hvm/vmx/vmx.c | 13 ++++++++++++-
> >   1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
> > index 6323bd6..40c7b0e 100644
> > --- a/xen/arch/x86/hvm/vmx/vmx.c
> > +++ b/xen/arch/x86/hvm/vmx/vmx.c
> > @@ -1663,9 +1663,20 @@ static void
> __vmx_deliver_posted_interrupt(struct vcpu *v)
> >
> >   static void vmx_deliver_posted_intr(struct vcpu *v, u8 vector)
> >   {
> > +    int r, sn;
> > +
> >       if ( pi_test_and_set_pir(vector, &v->arch.hvm_vmx.pi_desc) )
> >           return;
> >
> > +    /*
> > +     * Currently, we don't support urgent interrupt, all interrupts
> > +     * are recognized as non-urgent interrupt, so we cannot send
> > +     * posted-interrupt when 'SN' is set.
> > +     */
> > +
> > +    sn = pi_test_sn(&v->arch.hvm_vmx.pi_desc);
> 
> Is there anywhere which sets sn at all? I cant spot anywhere.
> 

SN is set in [13/15] while vCPU is going to runnable state.

Thanks,
Feng

> ~Andrew
> 
> > +    r = pi_test_and_set_on(&v->arch.hvm_vmx.pi_desc);
> > +
> >       if ( unlikely(v->arch.hvm_vmx.eoi_exitmap_changed) )
> >       {
> >           /*
> > @@ -1675,7 +1686,7 @@ static void vmx_deliver_posted_intr(struct vcpu *v,
> u8 vector)
> >            */
> >           pi_set_on(&v->arch.hvm_vmx.pi_desc);
> >       }
> > -    else if ( !pi_test_and_set_on(&v->arch.hvm_vmx.pi_desc) )
> > +    else if ( !r && !sn )
> >       {
> >           __vmx_deliver_posted_interrupt(v);
> >           return;


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