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From: Thomas Huth <thuth@redhat.com>
Message-ID: <56026D31.3050305@redhat.com>
Date: Wed, 23 Sep 2015 11:13:21 +0200
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Subject: Re: [Qemu-devel] [RFC PATCH 02/10] vfio: Generalize
 vfio_listener_region_add failure path
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To: David Gibson <david@gibson.dropbear.id.au>, alex.williamson@redhat.com, aik@ozlabs.ru, gwshan@linux.vnet.ibm.com
Cc: lvivier@redhat.com, pbonzini@redhat.com, qemu-ppc@nongnu.org, qemu-devel@nongnu.org

On 17/09/15 15:09, David Gibson wrote:
> If a DMA mapping operation fails in vfio_listener_region_add() it
> checks to see if we've already completed initial setup of the
> container.  If so it reports an error so the setup code can fail
> gracefully, otherwise throws a hw_error().
> 
> There are other potential failure cases in vfio_listener_region_add()
> which could benefit from the same logic, so move it to its own
> fail: block.  Later patches can use this to extend other failure cases
> to fail as gracefully as possible under the circumstances.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  hw/vfio/common.c | 26 +++++++++++++++-----------
>  1 file changed, 15 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index e3152f6..9953b9c 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -400,19 +400,23 @@ static void vfio_listener_region_add(MemoryListener *listener,
>          error_report("vfio_dma_map(%p, 0x%"HWADDR_PRIx", "
>                       "0x%"HWADDR_PRIx", %p) = %d (%m)",
>                       container, iova, end - iova, vaddr, ret);
> +        goto fail;
> +    }
>  
> -        /*
> -         * On the initfn path, store the first error in the container so we
> -         * can gracefully fail.  Runtime, there's not much we can do other
> -         * than throw a hardware error.
> -         */
> -        if (!container->iommu_data.initialized) {
> -            if (!container->iommu_data.error) {
> -                container->iommu_data.error = ret;
> -            }
> -        } else {
> -            hw_error("vfio: DMA mapping failed, unable to continue");
> +    return;
> +
> +fail:
> +    /*
> +     * On the initfn path, store the first error in the container so we
> +     * can gracefully fail.  Runtime, there's not much we can do other
> +     * than throw a hardware error.
> +     */
> +    if (!container->iommu_data.initialized) {
> +        if (!container->iommu_data.error) {
> +            container->iommu_data.error = ret;
>          }
> +    } else {
> +        hw_error("vfio: DMA mapping failed, unable to continue");
>      }
>  }

Reviewed-by: Thomas Huth <thuth@redhat.com>