From: Jason Gunthorpe <jgg@nvidia.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
Alex Williamson <alex.williamson@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Christoph Hellwig <hch@infradead.org>,
Kevin Tian <kevin.tian@intel.com>,
Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
Dan Williams <dan.j.williams@intel.com>,
rafael@kernel.org, Diana Craciun <diana.craciun@oss.nxp.com>,
Cornelia Huck <cohuck@redhat.com>,
Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
Jacob jun Pan <jacob.jun.pan@intel.com>,
Chaitanya Kulkarni <kch@nvidia.com>,
Stuart Yoder <stuyoder@gmail.com>,
Laurentiu Tudor <laurentiu.tudor@nxp.com>,
Thierry Reding <thierry.reding@gmail.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Jonathan Hunter <jonathanh@nvidia.com>,
Li Yang <leoyang.li@nxp.com>, Dmitry Osipenko <digetx@gmail.com>,
iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 07/14] PCI: Add driver dma ownership management
Date: Mon, 14 Feb 2022 09:11:17 -0400 [thread overview]
Message-ID: <20220214131117.GW4160@nvidia.com> (raw)
In-Reply-To: <YgpQOmBA7QJJu+2E@kroah.com>
On Mon, Feb 14, 2022 at 01:51:06PM +0100, Greg Kroah-Hartman wrote:
> On Mon, Feb 14, 2022 at 08:38:42AM -0400, Jason Gunthorpe wrote:
> > On Mon, Feb 14, 2022 at 11:03:42AM +0100, Greg Kroah-Hartman wrote:
> > > On Tue, Jan 04, 2022 at 09:56:37AM +0800, Lu Baolu wrote:
> > > > Multiple PCI devices may be placed in the same IOMMU group because
> > > > they cannot be isolated from each other. These devices must either be
> > > > entirely under kernel control or userspace control, never a mixture. This
> > > > checks and sets DMA ownership during driver binding, and release the
> > > > ownership during driver unbinding.
> > > >
> > > > The device driver may set a new flag (no_kernel_api_dma) to skip calling
> > > > iommu_device_use_dma_api() during the binding process. For instance, the
> > > > userspace framework drivers (vfio etc.) which need to manually claim
> > > > their own dma ownership when assigning the device to userspace.
> > > >
> > > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> > > > include/linux/pci.h | 5 +++++
> > > > drivers/pci/pci-driver.c | 21 +++++++++++++++++++++
> > > > 2 files changed, 26 insertions(+)
> > > >
> > > > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > > > index 18a75c8e615c..d29a990e3f02 100644
> > > > +++ b/include/linux/pci.h
> > > > @@ -882,6 +882,10 @@ struct module;
> > > > * created once it is bound to the driver.
> > > > * @driver: Driver model structure.
> > > > * @dynids: List of dynamically added device IDs.
> > > > + * @no_kernel_api_dma: Device driver doesn't use kernel DMA API for DMA.
> > > > + * Drivers which don't require DMA or want to manually claim the
> > > > + * owner type (e.g. userspace driver frameworks) could set this
> > > > + * flag.
> > >
> > > Again with the bikeshedding, but this name is a bit odd. Of course it's
> > > in the kernel, this is all kernel code, so you can drop that. And
> > > again, "negative" flags are rough. So maybe just "prevent_dma"?
> >
> > That is misleading too, it is not that DMA is prevented, but that the
> > kernel's dma_api has not been setup.
>
> "has not been" or "will not be"?
"has not been" as that action was supposed to happen before probe(),
but the flag skips it.
A driver that sets this flag can still decide to enable the dma API on
its own. eg tegra drivers do this.
> What you want to prevent is the iommu core claiming the device
> automatically, right? So how about "prevent_iommu_dma"?
"claim" is not a good description. iommu always "claims" the device -
eg sets a domain, sets the dev and bus parameters, etc.
This really is only about setting up the in-kernel dma api, eg
allowing dma_map_sg()/etc to work.
dma api is just one way to operate the iommu, there are others too.
Think of this flag as
false = the driver is going to use the dma api (most common)
true = the driver will decide how to use the iommu by itself
Does it help think of a clearer name?
Jason
next prev parent reply other threads:[~2022-02-14 13:11 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-04 1:56 [PATCH v5 00/14] Fix BUG_ON in vfio_iommu_group_notifier() Lu Baolu
2022-01-04 1:56 ` [PATCH v5 01/14] iommu: Add dma ownership management interfaces Lu Baolu
2022-01-04 10:08 ` Christoph Hellwig
2022-01-04 16:41 ` Bjorn Helgaas
2022-01-04 19:23 ` Jason Gunthorpe
2022-01-06 3:18 ` Lu Baolu
2022-01-06 3:54 ` Lu Baolu
2022-01-06 15:46 ` Jason Gunthorpe
2022-01-07 1:50 ` Lu Baolu
2022-01-06 3:43 ` Lu Baolu
2022-01-06 3:47 ` Lu Baolu
2022-01-06 3:51 ` Lu Baolu
2022-01-05 6:57 ` Lu Baolu
2022-01-04 1:56 ` [PATCH v5 02/14] driver core: Add dma_cleanup callback in bus_type Lu Baolu
2022-01-04 10:08 ` Christoph Hellwig
2022-01-04 12:39 ` Jason Gunthorpe
2022-01-04 13:04 ` Greg Kroah-Hartman
2022-02-08 5:55 ` Lu Baolu
2022-02-08 11:35 ` Greg Kroah-Hartman
2022-02-14 10:01 ` Greg Kroah-Hartman
2022-02-14 10:02 ` Greg Kroah-Hartman
2022-01-04 1:56 ` [PATCH v5 03/14] amba: Stop sharing platform_dma_configure() Lu Baolu
2022-01-04 1:56 ` [PATCH v5 04/14] driver core: platform: Add driver dma ownership management Lu Baolu
2022-02-14 9:59 ` Greg Kroah-Hartman
2022-02-14 13:18 ` Jason Gunthorpe
2022-02-14 13:37 ` Greg Kroah-Hartman
2022-02-14 13:43 ` Jason Gunthorpe
2022-01-04 1:56 ` [PATCH v5 05/14] amba: " Lu Baolu
2022-01-04 1:56 ` [PATCH v5 06/14] bus: fsl-mc: " Lu Baolu
2022-01-04 1:56 ` [PATCH v5 07/14] PCI: " Lu Baolu
2022-02-14 10:03 ` Greg Kroah-Hartman
2022-02-14 12:38 ` Jason Gunthorpe
2022-02-14 12:51 ` Greg Kroah-Hartman
2022-02-14 13:11 ` Jason Gunthorpe [this message]
2022-02-14 13:39 ` Greg Kroah-Hartman
2022-02-14 13:43 ` Jason Gunthorpe
2022-02-15 3:06 ` Lu Baolu
2022-02-23 18:00 ` Bjorn Helgaas
2022-02-23 18:07 ` Jason Gunthorpe
2022-01-04 1:56 ` [PATCH v5 08/14] PCI: pci_stub: Suppress kernel DMA ownership auto-claiming Lu Baolu
2022-01-04 1:56 ` [PATCH v5 09/14] PCI: portdrv: " Lu Baolu
2022-01-04 17:06 ` Bjorn Helgaas
2022-01-04 19:26 ` Jason Gunthorpe
2022-01-04 19:51 ` Bjorn Helgaas
2022-01-05 0:35 ` Jason Gunthorpe
2022-01-06 4:12 ` Lu Baolu
2022-01-06 18:32 ` Bjorn Helgaas
2022-01-07 1:53 ` Lu Baolu
2022-01-04 1:56 ` [PATCH v5 10/14] vfio: Set DMA ownership for VFIO devices Lu Baolu
2022-01-04 1:56 ` [PATCH v5 11/14] vfio: Remove use of vfio_group_viable() Lu Baolu
2022-01-04 1:56 ` [PATCH v5 12/14] vfio: Delete the unbound_list Lu Baolu
2022-01-04 1:56 ` [PATCH v5 13/14] vfio: Remove iommu group notifier Lu Baolu
2022-01-04 1:56 ` [PATCH v5 14/14] iommu: Remove iommu group changes notifier Lu Baolu
2022-01-04 12:48 ` [PATCH v5 00/14] Fix BUG_ON in vfio_iommu_group_notifier() Jason Gunthorpe
2022-01-05 6:52 ` Lu Baolu
2022-02-18 1:07 ` Lu Baolu
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=20220214131117.GW4160@nvidia.com \
--to=jgg@nvidia.com \
--cc=airlied@linux.ie \
--cc=alex.williamson@redhat.com \
--cc=ashok.raj@intel.com \
--cc=baolu.lu@linux.intel.com \
--cc=bhelgaas@google.com \
--cc=cohuck@redhat.com \
--cc=dan.j.williams@intel.com \
--cc=daniel@ffwll.ch \
--cc=diana.craciun@oss.nxp.com \
--cc=digetx@gmail.com \
--cc=eric.auger@redhat.com \
--cc=gregkh@linuxfoundation.org \
--cc=hch@infradead.org \
--cc=iommu@lists.linux-foundation.org \
--cc=jacob.jun.pan@intel.com \
--cc=jonathanh@nvidia.com \
--cc=joro@8bytes.org \
--cc=kch@nvidia.com \
--cc=kevin.tian@intel.com \
--cc=kvm@vger.kernel.org \
--cc=laurentiu.tudor@nxp.com \
--cc=leoyang.li@nxp.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pci@vger.kernel.org \
--cc=rafael@kernel.org \
--cc=robin.murphy@arm.com \
--cc=stuyoder@gmail.com \
--cc=thierry.reding@gmail.com \
--cc=will@kernel.org \
--cc=yi.l.liu@intel.com \
/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).