From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: arnd@arndb.de, gregkh@linuxfoundation.org,
iommu@lists.linux-foundation.org, zhangfei.gao@linaro.org,
linux-accelerators@lists.ozlabs.org
Subject: Re: [PATCH 0/2] iommu: Remove iommu_sva_ops::mm_exit()
Date: Wed, 8 Apr 2020 16:04:47 -0300 [thread overview]
Message-ID: <20200408190447.GB11886@ziepe.ca> (raw)
In-Reply-To: <20200408140427.212807-1-jean-philippe@linaro.org>
On Wed, Apr 08, 2020 at 04:04:25PM +0200, Jean-Philippe Brucker wrote:
> The IOMMU SVA API currently requires device drivers to implement an
> mm_exit() callback, which stops device jobs that do DMA. This function
> is called in the release() MMU notifier, when an address space that is
> shared with a device exits.
>
> It has been noted several time during discussions about SVA that
> cancelling DMA jobs can be slow and complex, and doing it in the
> release() notifier might cause synchronization issues (patch 2 has more
> background). Device drivers must in any case call unbind() to remove
> their bond, after stopping DMA from a more favorable context (release of
> a file descriptor).
>
> So after mm exits, rather than notifying device drivers, we can hold on
> to the PASID until unbind(), ask IOMMU drivers to silently abort DMA and
> Page Requests in the meantime. This change should relieve the mmput()
> path.
At least all the patch comments look like they are on the right track
to me, thanks for doing this.
Jason
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prev parent reply other threads:[~2020-04-08 19:04 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-08 14:04 [PATCH 0/2] iommu: Remove iommu_sva_ops::mm_exit() Jean-Philippe Brucker
2020-04-08 14:04 ` [PATCH 1/2] uacce: Remove mm_exit() op Jean-Philippe Brucker
2020-04-09 9:07 ` Zhangfei Gao
2020-04-09 9:44 ` Jean-Philippe Brucker
2020-04-08 14:04 ` [PATCH 2/2] iommu: Remove iommu_sva_ops::mm_exit() Jean-Philippe Brucker
2020-04-08 18:35 ` [PATCH 0/2] " Jacob Pan
2020-04-08 19:02 ` Jason Gunthorpe
2020-04-08 21:35 ` Jacob Pan
2020-04-08 22:32 ` Jason Gunthorpe
2020-04-08 23:48 ` Jacob Pan
2020-04-09 6:39 ` Jean-Philippe Brucker
2020-04-09 14:14 ` Jacob Pan
2020-04-09 14:25 ` Jason Gunthorpe
2020-04-09 16:21 ` Jacob Pan
2020-04-09 16:58 ` Jason Gunthorpe
2020-04-09 14:50 ` Jean-Philippe Brucker
2020-04-09 16:27 ` Jacob Pan
2020-04-10 15:52 ` Jacob Pan
2020-04-15 7:47 ` Jean-Philippe Brucker
2020-04-16 20:58 ` Jacob Pan
2020-04-20 8:02 ` Jean-Philippe Brucker
2020-04-09 12:08 ` Jason Gunthorpe
2020-04-09 16:31 ` Jacob Pan
2020-04-08 23:49 ` Fenghua Yu
2020-04-09 12:12 ` Jason Gunthorpe
2020-04-08 19:04 ` Jason Gunthorpe [this message]
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