iommu.lists.linux-foundation.org archive mirror
 help / color / mirror / Atom feed
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>,
	iommu@lists.linux-foundation.org,
	LKML <linux-kernel@vger.kernel.org>,
	Joerg Roedel <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>
Cc: "Tian, Kevin" <kevin.tian@intel.com>, Raj Ashok <ashok.raj@intel.com>
Subject: Re: [PATCH 7/7] iommu/vt-d: Disable multiple GPASID-dev bind
Date: Thu, 25 Jun 2020 20:54:22 +0800	[thread overview]
Message-ID: <e8725709-8720-ade2-34a3-999f0cf61fde@linux.intel.com> (raw)
In-Reply-To: <1592926996-47914-8-git-send-email-jacob.jun.pan@linux.intel.com>

On 2020/6/23 23:43, Jacob Pan wrote:
> For the unlikely use case where multiple aux domains from the same pdev
> are attached to a single guest and then bound to a single process
> (thus same PASID) within that guest, we cannot easily support this case
> by refcounting the number of users. As there is only one SL page table
> per PASID while we have multiple aux domains thus multiple SL page tables
> for the same PASID.
> 
> Extra unbinding guest PASID can happen due to race between normal and
> exception cases. Termination of one aux domain may affect others unless
> we actively track and switch aux domains to ensure the validity of SL
> page tables and TLB states in the shared PASID entry.
> 
> Support for sharing second level PGDs across domains can reduce the
> complexity but this is not available due to the limitations on VFIO
> container architecture. We can revisit this decision once sharing PGDs
> are available.
> 
> Overall, the complexity and potential glitch do not warrant this unlikely
> use case thereby removed by this patch.
> 
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>

Fixes: 56722a4398a30 ("iommu/vt-d: Add bind guest PASID support")
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

> ---
>   drivers/iommu/intel/svm.c | 22 +++++++++-------------
>   1 file changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index 6c87c807a0ab..d386853121a2 100644
> --- a/drivers/iommu/intel/svm.c
> +++ b/drivers/iommu/intel/svm.c
> @@ -277,20 +277,16 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
>   			goto out;
>   		}
>   
> +		/*
> +		 * Do not allow multiple bindings of the same device-PASID since
> +		 * there is only one SL page tables per PASID. We may revisit
> +		 * once sharing PGD across domains are supported.
> +		 */
>   		for_each_svm_dev(sdev, svm, dev) {
> -			/*
> -			 * For devices with aux domains, we should allow
> -			 * multiple bind calls with the same PASID and pdev.
> -			 */
> -			if (iommu_dev_feature_enabled(dev,
> -						      IOMMU_DEV_FEAT_AUX)) {
> -				sdev->users++;
> -			} else {
> -				dev_warn_ratelimited(dev,
> -						     "Already bound with PASID %u\n",
> -						     svm->pasid);
> -				ret = -EBUSY;
> -			}
> +			dev_warn_ratelimited(dev,
> +					     "Already bound with PASID %u\n",
> +					     svm->pasid);
> +			ret = -EBUSY;
>   			goto out;
>   		}
>   	} else {
> 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

      reply	other threads:[~2020-06-25 12:54 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23 15:43 [PATCH 0/7] iommu/vt-d: Misc tweaks and fixes for vSVA Jacob Pan
2020-06-23 15:43 ` [PATCH 1/7] iommu/vt-d: Enforce PASID devTLB field mask Jacob Pan
2020-06-25  7:14   ` Lu Baolu
2020-06-23 15:43 ` [PATCH 2/7] iommu/vt-d: Remove global page support in devTLB flush Jacob Pan
2020-06-25  7:17   ` Lu Baolu
2020-06-23 15:43 ` [PATCH 3/7] iommu/vt-d: Fix PASID devTLB invalidation Jacob Pan
2020-06-25  7:25   ` Lu Baolu
2020-06-30  3:01     ` Tian, Kevin
2020-06-30  4:58       ` Jacob Pan
2020-06-30  4:57     ` Jacob Pan
2020-06-23 15:43 ` [PATCH 4/7] iommu/vt-d: Handle non-page aligned address Jacob Pan
2020-06-25 10:05   ` Lu Baolu
2020-06-30 17:19     ` Jacob Pan
2020-06-23 15:43 ` [PATCH 5/7] iommu/vt-d: Fix devTLB flush for vSVA Jacob Pan
2020-06-23 20:12   ` kernel test robot
2020-06-24  0:38   ` Jacob Pan
2020-06-23 15:43 ` [PATCH 6/7] iommu/vt-d: Warn on out-of-range invalidation address Jacob Pan
2020-06-25 10:10   ` Lu Baolu
2020-06-30 17:34     ` Jacob Pan
2020-07-01  1:45       ` Lu Baolu
2020-07-01 14:19         ` Jacob Pan
2020-06-23 15:43 ` [PATCH 7/7] iommu/vt-d: Disable multiple GPASID-dev bind Jacob Pan
2020-06-25 12:54   ` Lu Baolu [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=e8725709-8720-ade2-34a3-999f0cf61fde@linux.intel.com \
    --to=baolu.lu@linux.intel.com \
    --cc=ashok.raj@intel.com \
    --cc=dwmw2@infradead.org \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jacob.jun.pan@linux.intel.com \
    --cc=joro@8bytes.org \
    --cc=kevin.tian@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).