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From: Jason Gunthorpe via iommu <iommu@lists.linux-foundation.org>
To: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Dave Jiang <dave.jiang@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	"Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
	Barry Song <21cnbao@gmail.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	iommu@lists.linux-foundation.org, mike.campin@intel.com
Subject: Re: [RFC 0/7] Support in-kernel DMA with PASID and SVA
Date: Thu, 7 Oct 2021 14:48:22 -0300	[thread overview]
Message-ID: <20211007174822.GK2744544@nvidia.com> (raw)
In-Reply-To: <20211007105010.33d706cf@jacob-builder>

On Thu, Oct 07, 2021 at 10:50:10AM -0700, Jacob Pan wrote:

> On platforms that are DMA snooped, this barrier is not needed. But I think
> your point is that once we convert to DMA API, the sync/barrier is covered
> by DMA APIs if !dev_is_dma_coherent(dev). Then all archs are good.

No.. my point is that a CPU store release is not necessary a DMA
visiable event on all platforms and things like dma_wmb/rmb() may
still be necessary. This all needs to be architected before anyone
starts writing drivers that assume a coherent DMA model without using
a coherent DMA allocation.

Jason
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  reply	other threads:[~2021-10-07 17:48 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-21 20:29 [RFC 0/7] Support in-kernel DMA with PASID and SVA Jacob Pan
2021-09-21 20:29 ` [RFC 1/7] ioasid: reserve special PASID for in-kernel DMA Jacob Pan
2021-09-21 20:29 ` [RFC 2/7] dma-iommu: Add API for DMA request with PASID Jacob Pan
2021-09-21 20:29 ` [RFC 3/7] iommu/vt-d: Add DMA w/ PASID support for PA and IOVA Jacob Pan
2021-09-21 20:29 ` [RFC 4/7] dma-iommu: Add support for DMA w/ PASID in KVA Jacob Pan
2021-09-21 20:29 ` [RFC 5/7] iommu/vt-d: Add support for KVA PASID mode Jacob Pan
2021-09-21 20:29 ` [RFC 6/7] iommu: Add KVA map API Jacob Pan
2021-09-21 20:29 ` [RFC 7/7] dma/idxd: Use dma-iommu PASID API instead of SVA lib Jacob Pan
2021-09-22 17:04 ` [RFC 0/7] Support in-kernel DMA with PASID and SVA Jason Gunthorpe via iommu
2021-09-29 19:37 ` Jacob Pan
2021-09-29 19:39   ` Jason Gunthorpe via iommu
2021-09-29 22:57     ` Jacob Pan
2021-09-29 23:43       ` Jason Gunthorpe via iommu
2021-09-30 14:22         ` Campin, Mike
2021-09-30 15:21           ` Jacob Pan
2021-10-01 12:24 ` Barry Song
2021-10-01 12:36   ` Jason Gunthorpe via iommu
2021-10-01 12:45     ` Barry Song
2021-10-04 16:40       ` Jacob Pan
2021-10-04 18:21         ` Jason Gunthorpe via iommu
2021-10-07  5:43           ` Barry Song
2021-10-07 11:32             ` Jason Gunthorpe via iommu
2021-10-07 11:54               ` Barry Song
2021-10-07 11:59                 ` Jason Gunthorpe via iommu
2021-10-07 17:50                   ` Jacob Pan
2021-10-07 17:48                     ` Jason Gunthorpe via iommu [this message]
2021-10-07 18:08                       ` Jacob Pan
2021-10-07 19:11             ` Jacob Pan
2021-10-07 19:10               ` Jason Gunthorpe via iommu

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