Re: [PATCH] KVM: arm64: vgic-debug: Don't put unmarked LPIs

Oliver Upton
2024-08-19T16:26:57Z

On Sat, Aug 17, 2024 at 06:31:45PM +0800, Zenghui Yu wrote:
> On 2024/8/17 18:25, Marc Zyngier wrote:
> > On Sat, 17 Aug 2024 11:15:41 +0100,
> > Zenghui Yu <yuzenghui@huawei.com> wrote:
> > >
> > > If there were LPIs being mapped behind our back (i.e., between .start() and
> > > .stop()), we would put them at iter_unmark_lpis() without checking if they
> > > were actually *marked*, which is obviously not good.
> > >
> > > Switch to use the xa_for_each_marked() iterator to fix it.

Urgh, that's what I'd meant to do. Thanks for catching this Zenghui.

> > > Fixes: 85d3ccc8b75b ("KVM: arm64: vgic-debug: Use an xarray mark for debug iterator")
> > > Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
> > > ---
> > > arch/arm64/kvm/vgic/vgic-debug.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/arch/arm64/kvm/vgic/vgic-debug.c b/arch/arm64/kvm/vgic/vgic-debug.c
> > > index bc74d06398ef..e1397ab2072a 100644
> > > --- a/arch/arm64/kvm/vgic/vgic-debug.c
> > > +++ b/arch/arm64/kvm/vgic/vgic-debug.c
> > > @@ -85,7 +85,7 @@ static void iter_unmark_lpis(struct kvm *kvm)
> > > struct vgic_irq *irq;
> > > unsigned long intid;
> > >
> > > - xa_for_each(&dist->lpi_xa, intid, irq) {
> > > + xa_for_each_marked(&dist->lpi_xa, intid, irq, LPI_XA_MARK_DEBUG_ITER) {
> > > xa_clear_mark(&dist->lpi_xa, intid, LPI_XA_MARK_DEBUG_ITER);
> > > vgic_put_irq(kvm, irq);
> > > }
> >
> > Ouch. Nicely caught. I think this deserves a
> >
> > Cc: stable@vger.kernel.org # v6.10
>
> Yup. I guess Oliver will help to add it when applying ;-)

Indeed, I'll grab it here in a moment.

> >
> > With that,
> >
> > Reviewed-by: Marc Zyngier <maz@kernel.org>
>

Thanks both!

--
Best,
Oliver