linux-kernel - Re: [PATCH 3/9] KVM: arm64: vgic-v3: Fix error handling in vgic_v3_set_redist

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Date:   Mon, 28 Dec 2020 15:35:11 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Eric Auger <eric.auger@...hat.com>
Cc:     eric.auger.pro@...il.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
        drjones@...hat.com, alexandru.elisei@....com, james.morse@....com,
        julien.thierry.kdev@...il.com, suzuki.poulose@....com,
        shuah@...nel.org, pbonzini@...hat.com
Subject: Re: [PATCH 3/9] KVM: arm64: vgic-v3: Fix error handling in vgic_v3_set_redist_base()

Hi Eric,

On Sat, 12 Dec 2020 18:50:04 +0000,
Eric Auger <eric.auger@...hat.com> wrote:
> 
> vgic_register_all_redist_iodevs may succeed while
> vgic_register_all_redist_iodevs fails. For example this can happen

The same function cannot both fail and succeed ;-) Can you shed some
light on what you had in mind?

> while adding a redistributor region overlapping a dist region. The
> failure only is detected on vgic_register_all_redist_iodevs when
> vgic_v3_check_base() gets called.
> 
> In such a case, remove the newly added redistributor region and free
> it.
> 
> Signed-off-by: Eric Auger <eric.auger@...hat.com>
> ---
>  arch/arm64/kvm/vgic/vgic-mmio-v3.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kvm/vgic/vgic-mmio-v3.c b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> index 8e8a862def76..581f0f490000 100644
> --- a/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-mmio-v3.c
> @@ -866,8 +866,14 @@ int vgic_v3_set_redist_base(struct kvm *kvm, u32 index, u64 addr, u32 count)
>  	 * afterwards will register the iodevs when needed.
>  	 */
>  	ret = vgic_register_all_redist_iodevs(kvm);
> -	if (ret)
> +	if (ret) {
> +		struct vgic_redist_region *rdreg =
> +			vgic_v3_rdist_region_from_index(kvm, index);
> +

nit: consider splitting declaration and assignment so that we avoid
the line split if you insist on the 80 character limit.

> +		list_del(&rdreg->list);
> +		kfree(rdreg);
>  		return ret;
> +	}
>  
>  	return 0;
>  }
> -- 
> 2.21.3
> 
> 

Thanks,

	M.

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