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To:     Eric Auger <eric.auger@redhat.com>
Subject: Re: [PATCH] KVM: arm/arm64: vgic-its: Fix restoration of unmapped  collections
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Date:   Fri, 13 Dec 2019 10:43:22 +0000
From:   Marc Zyngier <maz@kernel.org>
Cc:     <eric.auger.pro@gmail.com>, <linux-kernel@vger.kernel.org>,
        <kvmarm@lists.cs.columbia.edu>
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Hi Eric,

On 2019-12-13 09:42, Eric Auger wrote:
> Saving/restoring an unmapped collection is a valid scenario. For
> example this happens if a MAPTI command was sent, featuring an
> unmapped collection. At the moment the CTE fails to be restored.
> Only compare against the number of online vcpus if the rdist
> base is set.
>
> Cc: stable@vger.kernel.org # v4.11+
> Fixes: ea1ad53e1e31a ("KVM: arm64: vgic-its: Collection table 
> save/restore")
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
>  virt/kvm/arm/vgic/vgic-its.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c 
> b/virt/kvm/arm/vgic/vgic-its.c
> index 98c7360d9fb7..17920d1b350a 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -2475,7 +2475,8 @@ static int vgic_its_restore_cte(struct vgic_its
> *its, gpa_t gpa, int esz)
>  	target_addr = (u32)(val >> KVM_ITS_CTE_RDBASE_SHIFT);
>  	coll_id = val & KVM_ITS_CTE_ICID_MASK;
>
> -	if (target_addr >= atomic_read(&kvm->online_vcpus))
> +	if (target_addr != COLLECTION_NOT_MAPPED &&
> +	    target_addr >= atomic_read(&kvm->online_vcpus))
>  		return -EINVAL;
>
>  	collection = find_collection(its, coll_id);

Looks good to me. Out of curiosity, how was this spotted?

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...