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From: Joerg Roedel <joro@8bytes.org>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: alan.cox@intel.com, Christoph Hellwig <hch@lst.de>,
	Stefano Stabellini <sstabellini@kernel.org>,
	ashok.raj@intel.com, Jonathan Corbet <corbet@lwn.net>,
	pengfei.xu@intel.com, Ingo Molnar <mingo@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	kevin.tian@intel.com,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	mika.westerberg@linux.intel.com, Alan Cox <alan@linux.intel.com>,
	Juergen Gross <jgross@suse.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Mika Westerberg <mika.westerberg@intel.com>,
	linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
	jacob.jun.pan@intel.com, Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v6 5/8] iommu: Add bounce page APIs
Date: Thu, 15 Aug 2019 17:48:45 +0200
Message-ID: <20190815154845.GA18327@8bytes.org> (raw)
In-Reply-To: <445624e7-eb57-8089-8eb3-8687a65b1258@linux.intel.com>

On Thu, Aug 15, 2019 at 02:15:32PM +0800, Lu Baolu wrote:
> iommu_map/unmap() APIs haven't parameters for dma direction and
> attributions. These parameters are elementary for DMA APIs. Say,
> after map, if the dma direction is TO_DEVICE and a bounce buffer is
> used, we must sync the data from the original dma buffer to the bounce
> buffer; In the opposite direction, if dma is FROM_DEVICE, before unmap,
> we need to sync the data from the bounce buffer onto the original
> buffer.

The DMA direction from DMA-API maps to the protections in iommu_map():

	DMA_FROM_DEVICE:	IOMMU_WRITE
	DMA_TO_DEVICE:		IOMMU_READ
	DMA_BIDIRECTIONAL	IOMMU_READ | IOMMU_WRITE

And for the sync DMA-API also has separate functions for either
direction. So I don't see why these extra functions are needed in the
IOMMU-API.


Regards,

	Joerg
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  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-30  4:52 [PATCH v6 0/8] iommu: Bounce page for untrusted devices Lu Baolu
2019-07-30  4:52 ` [PATCH v6 1/8] iommu/vt-d: Don't switch off swiotlb if use direct dma Lu Baolu
2019-07-30  4:52 ` [PATCH v6 2/8] PCI: Add dev_is_untrusted helper Lu Baolu
2019-07-30  4:52 ` [PATCH v6 3/8] swiotlb: Split size parameter to map/unmap APIs Lu Baolu
2019-07-30  4:52 ` [PATCH v6 4/8] swiotlb: Zero out bounce buffer for untrusted device Lu Baolu
2019-07-30  4:52 ` [PATCH v6 5/8] iommu: Add bounce page APIs Lu Baolu
2019-08-14  8:38   ` Joerg Roedel
2019-08-15  6:15     ` Lu Baolu
2019-08-15 15:48       ` Joerg Roedel [this message]
2019-08-16  2:45         ` Lu Baolu
2019-08-16  4:46           ` Christoph Hellwig
2019-08-18  3:07             ` Lu Baolu
2019-07-30  4:52 ` [PATCH v6 6/8] iommu/vt-d: Check whether device requires bounce buffer Lu Baolu
2019-07-30  4:52 ` [PATCH v6 7/8] iommu/vt-d: Add trace events for device dma map/unmap Lu Baolu
2019-07-30  4:52 ` [PATCH v6 8/8] iommu/vt-d: Use bounce buffer for untrusted devices Lu Baolu

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