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

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Message-ID: <ZsNySeySMxxcpUTS@linux.dev>
Date: Mon, 19 Aug 2024 09:26:49 -0700
From: Oliver Upton <oliver.upton@...ux.dev>
To: Zenghui Yu <yuzenghui@...wei.com>
Cc: Marc Zyngier <maz@...nel.org>, kvmarm@...ts.linux.dev,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	james.morse@....com, suzuki.poulose@....com,
	wanghaibin.wang@...wei.com
Subject: Re: [PATCH] KVM: arm64: vgic-debug: Don't put unmarked LPIs

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@...wei.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@...wei.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@...r.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@...nel.org>
> 

Thanks both!

-- 
Best,
Oliver