linux-kernel - Re: [PATCH v2 04/12] iommu: Replace device fault handler with iommu_queue

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Message-ID: <ZNUq2IcvjEkwQewc@ziepe.ca>
Date:   Thu, 10 Aug 2023 15:22:16 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Nicolin Chen <nicolinc@...dia.com>,
        Yi Liu <yi.l.liu@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 04/12] iommu: Replace device fault handler with
 iommu_queue_iopf()

On Thu, Jul 27, 2023 at 01:48:29PM +0800, Lu Baolu wrote:
> The individual iommu drivers report iommu faults by calling
> iommu_report_device_fault(), where a pre-registered device fault handler
> is called to route the fault to another fault handler installed on the
> corresponding iommu domain.
> 
> The pre-registered device fault handler is static and won't be dynamic
> as the fault handler is eventually per iommu domain. Replace calling
> device fault handler with iommu_queue_iopf().
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/iommu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 4352a149a935..00309f66153b 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -1381,7 +1381,7 @@ int iommu_report_device_fault(struct device *dev, struct iommu_fault_event *evt)
>  		mutex_unlock(&fparam->lock);
>  	}
>  
> -	ret = fparam->handler(&evt->fault, fparam->data);
> +	ret = iommu_queue_iopf(&evt->fault, dev);
>  	if (ret && evt_pending) {
>  		mutex_lock(&fparam->lock);
>  		list_del(&evt_pending->list);

I don't get it, why not remove fparam->handler/data entirely in this
patch? There is no user once you do this change?

Jason