linux-kernel - Re: [PATCH 5/9] iommu: Make fault

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Date:   Tue, 11 Jul 2023 14:31:51 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        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>, iommu@...ts.linux.dev,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH 5/9] iommu: Make fault_param generic

Hi BaoLu,

On Tue, 11 Jul 2023 09:06:38 +0800, Lu Baolu <baolu.lu@...ux.intel.com>
wrote:

> The iommu faults, including recoverable faults (IO page faults) and
> unrecoverable faults (DMA faults), are generic to all devices. The
> iommu faults could possibly be triggered for every device.
> 
> The fault_param pointer under struct dev_iommu is the per-device fault
> data. Therefore, the fault_param pointer should be allocated during
> iommu device probe and freed when the device is released.
> 
> With this done, the individual iommu drivers that support iopf have no
> need to call iommu_[un]register_device_fault_handler() any more.
> This will make it easier for the iommu drivers to support iopf, and it
> will also make the fault_param allocation and free simpler.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c    | 13 +------------
>  drivers/iommu/intel/iommu.c                    | 18 ++++--------------
>  drivers/iommu/iommu.c                          | 14 ++++++++++++++
>  3 files changed, 19 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c index
> a5a63b1c947e..fa8ab9d413f8 100644 ---
> a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c +++
> b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c @@ -437,7 +437,6 @@
> bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master) 
>  static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master
> *master) {
> -	int ret;
>  	struct device *dev = master->dev;
>  
>  	/*
> @@ -450,16 +449,7 @@ static int arm_smmu_master_sva_enable_iopf(struct
> arm_smmu_master *master) if (!master->iopf_enabled)
>  		return -EINVAL;
>  
> -	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
> -	if (ret)
> -		return ret;
> -
> -	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf,
> dev);
> -	if (ret) {
> -		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
> -		return ret;
> -	}
> -	return 0;
> +	return iopf_queue_add_device(master->smmu->evtq.iopf, dev);
>  }
>  
>  static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master
> *master) @@ -469,7 +459,6 @@ static void
> arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master) if
> (!master->iopf_enabled) return;
>  
> -	iommu_unregister_device_fault_handler(dev);
>  	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
>  }
>  
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 5c8c5cdc36cf..22e43db20252 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4594,23 +4594,14 @@ static int intel_iommu_enable_iopf(struct device
> *dev) if (ret)
>  		return ret;
>  
> -	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf,
> dev);
> -	if (ret)
> -		goto iopf_remove_device;
> -
>  	ret = pci_enable_pri(pdev, PRQ_DEPTH);
> -	if (ret)
> -		goto iopf_unregister_handler;
> +	if (ret) {
> +		iopf_queue_remove_device(iommu->iopf_queue, dev);
> +		return ret;
> +	}
>  	info->pri_enabled = 1;
>  
>  	return 0;
> -
> -iopf_unregister_handler:
> -	iommu_unregister_device_fault_handler(dev);
> -iopf_remove_device:
> -	iopf_queue_remove_device(iommu->iopf_queue, dev);
> -
> -	return ret;
>  }
>  
>  static int intel_iommu_disable_iopf(struct device *dev)
> @@ -4637,7 +4628,6 @@ static int intel_iommu_disable_iopf(struct device
> *dev)
>  	 * fault handler and removing device from iopf queue should never
>  	 * fail.
>  	 */
> -	WARN_ON(iommu_unregister_device_fault_handler(dev));
>  	WARN_ON(iopf_queue_remove_device(iommu->iopf_queue, dev));
>  
>  	return 0;
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 65895b987e22..8d1f0935ea71 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -299,7 +299,15 @@ static int dev_iommu_get(struct device *dev)
>  		return -ENOMEM;
>  
>  	mutex_init(&param->lock);
> +	param->fault_param = kzalloc(sizeof(*param->fault_param),
> GFP_KERNEL);
since fault_param is _always_ allocated/freed along with param, can we merge
into one allocation? i.e.
 struct dev_iommu {
        struct mutex lock;
-       struct iommu_fault_param        *fault_param;
+       struct iommu_fault_param        fault_param;


> +	if (!param->fault_param) {
> +		kfree(param);
> +		return -ENOMEM;
> +	}
> +	mutex_init(&param->fault_param->lock);
> +	INIT_LIST_HEAD(&param->fault_param->faults);
>  	dev->iommu = param;
> +
>  	return 0;
>  }
>  
> @@ -312,6 +320,12 @@ static void dev_iommu_free(struct device *dev)
>  		fwnode_handle_put(param->fwspec->iommu_fwnode);
>  		kfree(param->fwspec);
>  	}
> +	/*
> +	 * All pending faults should have been drained before
> +	 * device release.
> +	 */
> +	WARN_ON_ONCE(!list_empty(&param->fault_param->faults));
> +	kfree(param->fault_param);
>  	kfree(param);
>  }
>  


Thanks,

Jacob