linux-kernel - Re: [PATCH v2 16/19] iommu/vtd: Clean up for SVM device list

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <d7db0f68-3b56-7fac-e290-8c57ad9dcb2c@redhat.com>
Date:   Fri, 26 Apr 2019 18:19:20 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe.brucker@....com>
Cc:     Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Christoph Hellwig <hch@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Andriy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: Re: [PATCH v2 16/19] iommu/vtd: Clean up for SVM device list

Hi

On 4/24/19 1:31 AM, Jacob Pan wrote:
> Use combined macro for_each_svm_dev() to simplify SVM device iteration.
> 
> Suggested-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Reviewed-by: Eric Auger <eric.auger@...hat.com>

Thanks

Eric

> ---
>  drivers/iommu/intel-svm.c | 76 ++++++++++++++++++++++-------------------------
>  1 file changed, 36 insertions(+), 40 deletions(-)
> 
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index 0a973c2..39dfb2e 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -447,15 +447,13 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
>  				goto out;
>  			}
>  
> -			list_for_each_entry(sdev, &svm->devs, list) {
> -				if (dev == sdev->dev) {
> -					if (sdev->ops != ops) {
> -						ret = -EBUSY;
> -						goto out;
> -					}
> -					sdev->users++;
> -					goto success;
> +			for_each_svm_dev() {
> +				if (sdev->ops != ops) {
> +					ret = -EBUSY;
> +					goto out;
>  				}
> +				sdev->users++;
> +				goto success;
>  			}
>  
>  			break;
> @@ -585,40 +583,38 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
>  	if (!svm)
>  		goto out;
>  
> -	list_for_each_entry(sdev, &svm->devs, list) {
> -		if (dev == sdev->dev) {
> -			ret = 0;
> -			sdev->users--;
> -			if (!sdev->users) {
> -				list_del_rcu(&sdev->list);
> -				/* Flush the PASID cache and IOTLB for this device.
> -				 * Note that we do depend on the hardware *not* using
> -				 * the PASID any more. Just as we depend on other
> -				 * devices never using PASIDs that they have no right
> -				 * to use. We have a *shared* PASID table, because it's
> -				 * 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, !svm->mm);
> -				kfree_rcu(sdev, rcu);
> -
> -				if (list_empty(&svm->devs)) {
> -					ioasid_free(svm->pasid);
> -					if (svm->mm)
> -						mmu_notifier_unregister(&svm->notifier, svm->mm);
> -
> -					list_del(&svm->list);
> -
> -					/* We mandate that no page faults may be outstanding
> -					 * for the PASID when intel_svm_unbind_mm() is called.
> -					 * If that is not obeyed, subtle errors will happen.
> -					 * Let's make them less subtle... */
> -					memset(svm, 0x6b, sizeof(*svm));
> -					kfree(svm);
> -				}
> +	for_each_svm_dev() {
> +		ret = 0;
> +		sdev->users--;
> +		if (!sdev->users) {
> +			list_del_rcu(&sdev->list);
> +			/* Flush the PASID cache and IOTLB for this device.
> +			 * Note that we do depend on the hardware *not* using
> +			 * the PASID any more. Just as we depend on other
> +			 * devices never using PASIDs that they have no right
> +			 * to use. We have a *shared* PASID table, because it's
> +			 * 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, !svm->mm);
> +			kfree_rcu(sdev, rcu);
> +
> +			if (list_empty(&svm->devs)) {
> +				ioasid_free(svm->pasid);
> +				if (svm->mm)
> +					mmu_notifier_unregister(&svm->notifier, svm->mm);
> +
> +				list_del(&svm->list);
> +
> +				/* We mandate that no page faults may be outstanding
> +				 * for the PASID when intel_svm_unbind_mm() is called.
> +				 * If that is not obeyed, subtle errors will happen.
> +				 * Let's make them less subtle... */
> +				memset(svm, 0x6b, sizeof(*svm));
> +				kfree(svm);
>  			}
> -			break;
>  		}
> +		break;
>  	}
>   out:
>  	mutex_unlock(&pasid_mutex);
>