IOMMU Archive on lore.kernel.org
 help / color / Atom feed
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>
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: Fri, 16 Aug 2019 10:45:13 +0800
Message-ID: <ec1dc4e2-626c-9c12-f17c-b51420fc2e81@linux.intel.com> (raw)
In-Reply-To: <20190815154845.GA18327@8bytes.org>

Hi Joerg,

On 8/15/19 11:48 PM, Joerg Roedel wrote:
> 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.
>

Okay. I understand that adding these APIs in iommu.c is not a good idea.
And, I also don't think merging the bounce buffer implementation into
iommu_map() is feasible since iommu_map() is not DMA API centric.

The bounce buffer implementation will eventually be part of DMA APIs
defined in dma-iommu.c, but currently those APIs are not ready for x86
use yet. So I will put them in iommu/vt-d driver for this time being and
will move them to dma-iommu.c later.

Does this work for you?

Best regards,
Lu Baolu
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  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
2019-08-16  2:45         ` Lu Baolu [this message]
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

Reply instructions:

You may reply publically 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=ec1dc4e2-626c-9c12-f17c-b51420fc2e81@linux.intel.com \
    --to=baolu.lu@linux.intel.com \
    --cc=alan.cox@intel.com \
    --cc=alan@linux.intel.com \
    --cc=ashok.raj@intel.com \
    --cc=bhelgaas@google.com \
    --cc=boris.ostrovsky@oracle.com \
    --cc=corbet@lwn.net \
    --cc=dwmw2@infradead.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=jacob.jun.pan@intel.com \
    --cc=jgross@suse.com \
    --cc=joro@8bytes.org \
    --cc=kevin.tian@intel.com \
    --cc=konrad.wilk@oracle.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mika.westerberg@intel.com \
    --cc=mika.westerberg@linux.intel.com \
    --cc=mingo@redhat.com \
    --cc=pengfei.xu@intel.com \
    --cc=robin.murphy@arm.com \
    --cc=rostedt@goodmis.org \
    --cc=sstabellini@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

IOMMU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-iommu/0 linux-iommu/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-iommu linux-iommu/ https://lore.kernel.org/linux-iommu \
		iommu@lists.linux-foundation.org iommu@archiver.kernel.org
	public-inbox-index linux-iommu


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.linux-foundation.lists.iommu


AGPL code for this site: git clone https://public-inbox.org/ public-inbox