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

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Message-ID: <86a5hbzbrt.wl-maz@kernel.org>
Date: Sat, 17 Aug 2024 11:25:42 +0100
From: Marc Zyngier <maz@...nel.org>
To: Zenghui Yu <yuzenghui@...wei.com>
Cc: <kvmarm@...ts.linux.dev>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>,
	<oliver.upton@...ux.dev>,
	<james.morse@....com>,
	<suzuki.poulose@....com>,
	<wanghaibin.wang@...wei.com>
Subject: Re: [PATCH] KVM: arm64: vgic-debug: Don't put unmarked LPIs

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.
> 
> 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

With that,

Reviewed-by: Marc Zyngier <maz@...nel.org>

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.