linux-kernel - Re: [PATCH v9 13/14] iommu: Improve iopf_queue_remove

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Date: Fri, 5 Jan 2024 12:25:40 -0400
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>,
	Longfang Liu <liulongfang@...wei.com>,
	Yan Zhao <yan.y.zhao@...el.com>, iommu@...ts.linux.dev,
	kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v9 13/14] iommu: Improve iopf_queue_remove_device()

On Wed, Dec 20, 2023 at 09:23:31AM +0800, Lu Baolu wrote:
> -int iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev)
> +void iopf_queue_remove_device(struct iopf_queue *queue, struct device *dev)
>  {
> -	int ret = 0;
>  	struct iopf_fault *iopf, *next;
> +	struct iommu_page_response resp;
>  	struct dev_iommu *param = dev->iommu;
>  	struct iommu_fault_param *fault_param;
> +	const struct iommu_ops *ops = dev_iommu_ops(dev);
>  
>  	mutex_lock(&queue->lock);
>  	mutex_lock(&param->lock);
>  	fault_param = rcu_dereference_check(param->fault_param,
>  					    lockdep_is_held(&param->lock));
> -	if (!fault_param) {
> -		ret = -ENODEV;
> -		goto unlock;
> -	}
> -
> -	if (fault_param->queue != queue) {
> -		ret = -EINVAL;
> -		goto unlock;
> -	}
>  
> -	if (!list_empty(&fault_param->faults)) {
> -		ret = -EBUSY;
> +	if (WARN_ON(!fault_param || fault_param->queue != queue))
>  		goto unlock;
> -	}
> -
> -	list_del(&fault_param->queue_list);
>  
> -	/* Just in case some faults are still stuck */
> +	mutex_lock(&fault_param->lock);
>  	list_for_each_entry_safe(iopf, next, &fault_param->partial, list)
>  		kfree(iopf);
>  
> +	list_for_each_entry_safe(iopf, next, &fault_param->faults, list) {
> +		memset(&resp, 0, sizeof(struct iommu_page_response));
> +		resp.pasid = iopf->fault.prm.pasid;
> +		resp.grpid = iopf->fault.prm.grpid;
> +		resp.code = IOMMU_PAGE_RESP_INVALID;

I would probably move the resp and iopf variables into here:

		struct iopf_fault *iopf = &group->last_fault;
		struct iommu_page_response resp = {
			.pasid = iopf->fault.prm.pasid,
			.grpid = iopf->fault.prm.grpid,
			.code = IOMMU_PAGE_RESP_INVALID
		};

(and call the other one partial_iopf)

But this looks fine either way

Reviewed-by: Jason Gunthorpe <jgg@...dia.com>

Jason