All of lore.kernel.org
 help / color / mirror / Atom feed
From: Jason Gunthorpe <jgg@nvidia.com>
To: Oded Gabbay <ogabbay@kernel.org>
Cc: "Christian König" <christian.koenig@amd.com>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Maling list - DRI developers" <dri-devel@lists.freedesktop.org>,
	"KVM list" <kvm@vger.kernel.org>,
	"moderated list:DMA BUFFER SHARING FRAMEWORK"
	<linaro-mm-sig@lists.linaro.org>,
	"Linux Media Mailing List" <linux-media@vger.kernel.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Leon Romanovsky" <leon@kernel.org>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	"Maor Gottlieb" <maorg@nvidia.com>
Subject: Re: [PATCH v2 4/4] vfio/pci: Allow MMIO regions to be exported through dma-buf
Date: Tue, 6 Sep 2022 14:59:11 -0300	[thread overview]
Message-ID: <YxeKb9qxFXodg832@nvidia.com> (raw)
In-Reply-To: <CAFCwf115rwTWzgPXcpog4u5NAvH4JO+Qis_fcx0mRrNR5AQcaQ@mail.gmail.com>

On Tue, Sep 06, 2022 at 03:34:02PM +0300, Oded Gabbay wrote:

> > > > > + /*
> > > > > +  * Since the memory being mapped is a device memory it could never be in
> > > > > +  * CPU caches.
> > > > > +  */
> > > > DMA_ATTR_SKIP_CPU_SYNC doesn't even apply to dma_map_resource, not sure
> > > > where this wisdom comes from.
> >
> > Habana driver
> I hate to throw the ball at someone else, but I actually copied the
> code from the amdgpu driver, from amdgpu_vram_mgr_alloc_sgt() iirc.
> And if you remember Jason, you asked why we use this specific define
> in the original review you did and I replied the following (to which
> you agreed and that's why we added the comment):

Yes, I remember, but Christophs remark is that DMA_ATTR_SKIP_CPU_SYNC
doesn't even do anything when passed to dma_map_resource().

The only attr that seems to be used is DMA_ATTR_PRIVILEGED from what I
can see.

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Oded Gabbay <ogabbay@kernel.org>
Cc: "moderated list:DMA BUFFER SHARING FRAMEWORK"
	<linaro-mm-sig@lists.linaro.org>,
	"Leon Romanovsky" <leon@kernel.org>,
	"KVM list" <kvm@vger.kernel.org>,
	linux-rdma <linux-rdma@vger.kernel.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Cornelia Huck" <cohuck@redhat.com>,
	"Maling list - DRI developers" <dri-devel@lists.freedesktop.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	"Christoph Hellwig" <hch@infradead.org>,
	"Alex Williamson" <alex.williamson@redhat.com>,
	"Maor Gottlieb" <maorg@nvidia.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Linux Media Mailing List" <linux-media@vger.kernel.org>
Subject: Re: [PATCH v2 4/4] vfio/pci: Allow MMIO regions to be exported through dma-buf
Date: Tue, 6 Sep 2022 14:59:11 -0300	[thread overview]
Message-ID: <YxeKb9qxFXodg832@nvidia.com> (raw)
In-Reply-To: <CAFCwf115rwTWzgPXcpog4u5NAvH4JO+Qis_fcx0mRrNR5AQcaQ@mail.gmail.com>

On Tue, Sep 06, 2022 at 03:34:02PM +0300, Oded Gabbay wrote:

> > > > > + /*
> > > > > +  * Since the memory being mapped is a device memory it could never be in
> > > > > +  * CPU caches.
> > > > > +  */
> > > > DMA_ATTR_SKIP_CPU_SYNC doesn't even apply to dma_map_resource, not sure
> > > > where this wisdom comes from.
> >
> > Habana driver
> I hate to throw the ball at someone else, but I actually copied the
> code from the amdgpu driver, from amdgpu_vram_mgr_alloc_sgt() iirc.
> And if you remember Jason, you asked why we use this specific define
> in the original review you did and I replied the following (to which
> you agreed and that's why we added the comment):

Yes, I remember, but Christophs remark is that DMA_ATTR_SKIP_CPU_SYNC
doesn't even do anything when passed to dma_map_resource().

The only attr that seems to be used is DMA_ATTR_PRIVILEGED from what I
can see.

Jason

  reply	other threads:[~2022-09-06 17:59 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-31 23:12 [PATCH v2 0/4] Allow MMIO regions to be exported through dma-buf Jason Gunthorpe
2022-08-31 23:12 ` Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 1/4] dma-buf: Add dma_buf_try_get() Jason Gunthorpe
2022-08-31 23:12   ` Jason Gunthorpe
2022-09-01  7:55   ` Christian König
2022-09-01  7:55     ` Christian König
2022-09-06 16:44     ` Jason Gunthorpe
2022-09-06 16:44       ` Jason Gunthorpe
2022-09-06 17:52       ` Christian König
2022-09-06 17:52         ` Christian König
2022-08-31 23:12 ` [PATCH v2 2/4] vfio: Add vfio_device_get() Jason Gunthorpe
2022-08-31 23:12   ` Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 3/4] vfio_pci: Do not open code pci_try_reset_function() Jason Gunthorpe
2022-08-31 23:12   ` Jason Gunthorpe
2022-08-31 23:12 ` [PATCH v2 4/4] vfio/pci: Allow MMIO regions to be exported through dma-buf Jason Gunthorpe
2022-08-31 23:12   ` Jason Gunthorpe
2022-09-06  9:51   ` Christoph Hellwig
2022-09-06 10:38     ` Christian König
2022-09-06 10:38       ` Christian König
2022-09-06 11:48       ` Jason Gunthorpe
2022-09-06 11:48         ` Jason Gunthorpe
2022-09-06 12:34         ` Oded Gabbay
2022-09-06 12:34           ` Oded Gabbay
2022-09-06 17:59           ` Jason Gunthorpe [this message]
2022-09-06 17:59             ` Jason Gunthorpe
2022-09-06 19:44             ` Oded Gabbay
2022-09-06 19:44               ` Oded Gabbay
2022-09-07 12:07               ` Christoph Hellwig
2022-09-07 12:05         ` Christoph Hellwig
2022-09-07 12:33           ` Jason Gunthorpe
2022-09-07 12:33             ` Jason Gunthorpe
2022-09-07 14:29             ` Christoph Hellwig
2022-09-07 14:46               ` Oded Gabbay
2022-09-07 14:46                 ` Oded Gabbay
2022-09-07 15:23               ` Jason Gunthorpe
2022-09-07 15:23                 ` Jason Gunthorpe
2022-09-07 15:32                 ` Christoph Hellwig
2022-09-07 16:12                   ` Jason Gunthorpe
2022-09-07 16:12                     ` Jason Gunthorpe
2022-09-09 13:24                     ` Christoph Hellwig
2022-09-09 14:09                       ` Jason Gunthorpe
2022-09-09 14:09                         ` Jason Gunthorpe
2022-09-07 16:31                 ` Robin Murphy
2022-09-07 16:31                   ` Robin Murphy
2022-09-07 16:47                   ` Jason Gunthorpe
2022-09-07 16:47                     ` Jason Gunthorpe
2022-09-07 17:03               ` Dan Williams
2022-09-07 17:03                 ` Dan Williams
2022-09-07 15:01             ` Robin Murphy
2022-09-07 15:01               ` Robin Murphy
2022-09-07 12:03       ` Christoph Hellwig
2022-09-07 15:08         ` Christian König
2022-09-07 15:08           ` Christian König
2022-09-07 15:23           ` Christoph Hellwig

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=YxeKb9qxFXodg832@nvidia.com \
    --to=jgg@nvidia.com \
    --cc=alex.williamson@redhat.com \
    --cc=christian.koenig@amd.com \
    --cc=cohuck@redhat.com \
    --cc=daniel.vetter@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=hch@infradead.org \
    --cc=kvm@vger.kernel.org \
    --cc=leon@kernel.org \
    --cc=linaro-mm-sig@lists.linaro.org \
    --cc=linux-media@vger.kernel.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=maorg@nvidia.com \
    --cc=ogabbay@kernel.org \
    --cc=sumit.semwal@linaro.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
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.