On Mon, Nov 18, 2019 at 04:37:16PM +0100, Cédric Le Goater wrote: > On 18/11/2019 16:12, Greg Kurz wrote: > > When using the XIVE KVM device, the trigger page is directly accessible > > in QEMU. Unlike with XICS, no need to ask KVM to fire the interrupt. A > > simple store on the trigger page does the job. > > > > Just call xive_esb_trigger(). > > Yes but the KVM XIVE device does a few other checks. > > It checks that the interrupt was correctly initialized at the KVM device > level. We should be fine in QEMU which has similar checks. > > It caches the LSI assertion level. We should be fine also because it is > useless in KVM when using the XIVE native exploitation mode. > > It checks it is not a passthru interrupt. Any idea on how to check this > condition under QEMU ? > > > This may improve performance of emulated devices that go through > > qemu_set_irq(), eg. virtio devices created with ioeventfd=off or > > configured by the guest to use LSI interrupts, which aren't really > > recommended setups. > > LGTM.
Ok, between the comments above and this, I'm not sure if this is ready
to merge or not.
>
> Any figures to share ?
>
> C.
>
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > ---
> > hw/intc/spapr_xive_kvm.c | 16 ++--------------
> > 1 file changed, 2 insertions(+), 14 deletions(-)
> >
> > diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> > index 08012ac7cd76..69e73552f1ef 100644
> > --- a/hw/intc/spapr_xive_kvm.c
> > +++ b/hw/intc/spapr_xive_kvm.c
> > @@ -354,32 +354,20 @@ static void kvmppc_xive_source_get_state(XiveSource
> > *xsrc)
> > void kvmppc_xive_source_set_irq(void *opaque, int srcno, int val)
> > {
> > XiveSource *xsrc = opaque;
> > - SpaprXive *xive = SPAPR_XIVE(xsrc->xive);
> > - struct kvm_irq_level args;
> > - int rc;
> > -
> > - /* The KVM XIVE device should be in use */
> > - assert(xive->fd != -1);
> >
> > - args.irq = srcno;
> > if (!xive_source_irq_is_lsi(xsrc, srcno)) {
> > if (!val) {
> > return;
> > }
> > - args.level = KVM_INTERRUPT_SET;
> > } else {
> > if (val) {
> > xsrc->status[srcno] |= XIVE_STATUS_ASSERTED;
> > - args.level = KVM_INTERRUPT_SET_LEVEL;
> > } else {
> > xsrc->status[srcno] &= ~XIVE_STATUS_ASSERTED;
> > - args.level = KVM_INTERRUPT_UNSET;
> > }
> > }
> > - rc = kvm_vm_ioctl(kvm_state, KVM_IRQ_LINE, &args);
> > - if (rc < 0) {
> > - error_report("XIVE: kvm_irq_line() failed : %s", strerror(errno));
> > - }
> > +
> > + xive_esb_trigger(xsrc, srcno);
> > }
>
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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