linux-kernel - RE: [PATCH v4 5/5] iommu/vt-d: Remove redundant IOTLB flush

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Date:   Thu, 7 May 2020 06:37:02 +0000
From:   "Tian, Kevin" <kevin.tian@...el.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>
CC:     "Raj, Ashok" <ashok.raj@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>
Subject: RE: [PATCH v4 5/5] iommu/vt-d: Remove redundant IOTLB flush

> From: Lu Baolu
> Sent: Thursday, May 7, 2020 8:56 AM
> 
> IOTLB flush already included in the PASID tear down and the page request
> drain process. There is no need to flush again.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
>  drivers/iommu/intel-svm.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 7256eb965cf6..5ff05adc96e9 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -209,11 +209,9 @@ static void intel_mm_release(struct mmu_notifier
> *mn, struct mm_struct *mm)
>  	 * *has* to handle gracefully without affecting other processes.
>  	 */
>  	rcu_read_lock();
> -	list_for_each_entry_rcu(sdev, &svm->devs, list) {
> +	list_for_each_entry_rcu(sdev, &svm->devs, list)
>  		intel_pasid_tear_down_entry(svm->iommu, sdev->dev,
>  					    svm->pasid, true);
> -		intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
> -	}
>  	rcu_read_unlock();
> 
>  }
> @@ -407,7 +405,6 @@ int intel_svm_unbind_gpasid(struct device *dev, int
> pasid)
>  			intel_pasid_tear_down_entry(iommu, dev,
>  						    svm->pasid, false);
>  			intel_svm_drain_prq(dev, svm->pasid);
> -			intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>  			kfree_rcu(sdev, rcu);
> 
>  			if (list_empty(&svm->devs)) {
> @@ -647,7 +644,6 @@ int intel_svm_unbind_mm(struct device *dev, int
> pasid)
>  			intel_pasid_tear_down_entry(iommu, dev,
>  						    svm->pasid, false);
>  			intel_svm_drain_prq(dev, svm->pasid);
> -			intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>  			kfree_rcu(sdev, rcu);
> 
>  			if (list_empty(&svm->devs)) {
> --
> 2.17.1

Reviewed-by: Kevin Tian <kevin.tian@...el.com>