Re: [PATCH 1/3] iommu/vt-d: Remove redundant IOTLB flush

[Lu Baolu]

On 2020/3/20 12:32, Jacob Pan wrote:
> IOTLB flush already included in the PASID tear down process. There
> is no need to flush again.

It seems that intel_pasid_tear_down_entry() doesn't flush the pasid
based device TLB?

Best regards,
baolu

> Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> ---
>   drivers/iommu/intel-svm.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 8f42d717d8d7..1483f1845762 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -268,10 +268,9 @@ 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);
> -		intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
> -	}
> +
>   	rcu_read_unlock();
>   
>   }
> @@ -731,7 +730,6 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
>   			 * large and has to be physically contiguous. So it's
>   			 * hard to be as defensive as we might like. */
>   			intel_pasid_tear_down_entry(iommu, dev, svm->pasid);
> -			intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
>   			kfree_rcu(sdev, rcu);
>   
>   			if (list_empty(&svm->devs)) {