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From: Jason Gunthorpe <jgg@mellanox.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Zhu Lingshan <lingshan.zhu@linux.intel.com>,
	mst@redhat.com, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	netdev@vger.kernel.org, tiwei.bie@intel.com,
	maxime.coquelin@redhat.com, cunming.liang@intel.com,
	zhihong.wang@intel.com, rob.miller@broadcom.com,
	xiao.w.wang@intel.com, haotian.wang@sifive.com,
	lingshan.zhu@intel.com, eperezma@redhat.com, lulu@redhat.com,
	parav@mellanox.com, kevin.tian@intel.com, stefanha@redhat.com,
	rdunlap@infradead.org, hch@infradead.org, aadam@redhat.com,
	jakub.kicinski@netronome.com, jiri@mellanox.com,
	shahafs@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com
Subject: Re: [PATCH 5/5] vdpasim: vDPA device simulator
Date: Tue, 4 Feb 2020 08:52:04 -0400
Message-ID: <20200204125204.GS23346@mellanox.com> (raw)
In-Reply-To: <cca7901b-51dd-4f4b-5c30-c42577ad5194@redhat.com>

On Tue, Feb 04, 2020 at 04:28:27PM +0800, Jason Wang wrote:
> 
> On 2020/2/4 下午4:21, Zhu Lingshan wrote:
> > > +static const struct dma_map_ops vdpasim_dma_ops = {
> > > +    .map_page = vdpasim_map_page,
> > > +    .unmap_page = vdpasim_unmap_page,
> > > +    .alloc = vdpasim_alloc_coherent,
> > > +    .free = vdpasim_free_coherent,
> > > +};
> > > +
> > 
> > Hey Jason,
> > 
> > IMHO, it would be nice if dma_ops of the parent device could be re-used.
> > vdpa_device is expecting to represent a physical device except this
> > simulator, however, there are not enough information in vdpa_device.dev
> > to indicating which kind physical device it attached to. Namely
> > get_arch_dma_ops(struct bus type) can not work on vdpa_device.dev. Then
> > it seems device drivers need to implement a wrap of dma_ops of parent
> > devices. Can this work be done in the vdpa framework since it looks like
> > a common task? Can "vd_dev->vdev.dev.parent = vdpa->dev->parent;" in
> > virtio_vdpa_probe() do the work?
> > 
> > Thanks,
> > BR
> > Zhu Lingshan
> 
> 
> Good catch.
> 
> I think we can.

IMHO you need to specify some 'dma_device', not try and play tricks
with dma_ops, or assuming the parent is always the device used for
dma.

Jason

  reply index

Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-16 12:42 [PATCH 0/5] vDPA support Jason Wang
2020-01-16 12:42 ` [PATCH 1/5] vhost: factor out IOTLB Jason Wang
2020-01-17  4:14   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-18  0:01   ` kbuild test robot
2020-01-18  0:40   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 2/5] vringh: IOTLB support Jason Wang
2020-01-17 21:54   ` kbuild test robot
2020-01-17 22:33   ` kbuild test robot
2020-01-16 12:42 ` [PATCH 3/5] vDPA: introduce vDPA bus Jason Wang
2020-01-16 15:22   ` Jason Gunthorpe
2020-01-17  3:03     ` Jason Wang
2020-01-17 13:54       ` Jason Gunthorpe
2020-01-20  7:50         ` Jason Wang
2020-01-20 12:17         ` Michael S. Tsirkin
2020-01-20 17:50           ` Jason Gunthorpe
2020-01-20 21:56             ` Michael S. Tsirkin
2020-01-21 14:12               ` Jason Gunthorpe
2020-01-21 14:15                 ` Michael S. Tsirkin
2020-01-21 14:16                   ` Jason Gunthorpe
2020-01-21  8:40       ` Tian, Kevin
2020-01-21  9:41         ` Jason Wang
2020-01-17  4:16   ` Randy Dunlap
2020-01-17  9:34     ` Jason Wang
2020-01-17 12:13   ` Michael S. Tsirkin
2020-01-17 13:52     ` Jason Wang
     [not found]       ` <CAJPjb1+fG9L3=iKbV4Vn13VwaeDZZdcfBPvarogF_Nzhk+FnKg@mail.gmail.com>
2020-01-19  9:07         ` Shahaf Shuler
2020-01-19  9:59           ` Michael S. Tsirkin
2020-01-20  8:44             ` Jason Wang
2020-01-20 12:09               ` Michael S. Tsirkin
2020-01-21  3:32                 ` Jason Wang
2020-01-20  8:43           ` Jason Wang
2020-01-20 17:49             ` Jason Gunthorpe
2020-01-20 20:51               ` Shahaf Shuler
2020-01-20 21:25                 ` Michael S. Tsirkin
2020-01-20 21:47                   ` Shahaf Shuler
2020-01-20 21:59                     ` Michael S. Tsirkin
2020-01-21  6:01                       ` Shahaf Shuler
2020-01-21  7:57                         ` Jason Wang
2020-01-21 14:07                   ` Jason Gunthorpe
2020-01-21 14:16                     ` Michael S. Tsirkin
2020-01-20 21:48               ` Michael S. Tsirkin
2020-01-21  4:00               ` Jason Wang
2020-01-21  5:47                 ` Michael S. Tsirkin
2020-01-21  8:00                   ` Jason Wang
2020-01-21  8:15                     ` Michael S. Tsirkin
2020-01-21  8:35                       ` Jason Wang
2020-01-21 11:09                         ` Shahaf Shuler
2020-01-22  6:36                           ` Jason Wang
2020-01-21 14:05                       ` Jason Gunthorpe
2020-01-21 14:17                         ` Michael S. Tsirkin
2020-01-22  6:18                           ` Jason Wang
2020-01-20  8:19         ` Jason Wang
2020-01-16 12:42 ` [PATCH 4/5] virtio: introduce a vDPA based transport Jason Wang
2020-01-16 15:38   ` Jason Gunthorpe
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:00       ` Jason Gunthorpe
2020-01-20  7:52         ` Jason Wang
2020-01-17  4:10   ` Randy Dunlap
2020-01-16 12:42 ` [PATCH 5/5] vdpasim: vDPA device simulator Jason Wang
2020-01-16 15:47   ` Jason Gunthorpe
2020-01-17  9:32     ` Jason Wang
2020-01-17 14:10       ` Jason Gunthorpe
2020-01-20  8:01         ` Jason Wang
2020-02-04  4:19         ` Jason Wang
2020-01-17  4:12   ` Randy Dunlap
2020-01-17  9:35     ` Jason Wang
2020-01-18 18:18   ` kbuild test robot
2020-01-28  3:32   ` Dan Carpenter
2020-02-04  4:07     ` Jason Wang
2020-02-04  8:21   ` Zhu Lingshan
2020-02-04  8:28     ` Jason Wang
2020-02-04 12:52       ` Jason Gunthorpe [this message]
2020-02-05  3:14         ` Jason Wang
2020-01-21  8:44 ` [PATCH 0/5] vDPA support Tian, Kevin
2020-01-21  9:39   ` Jason Wang

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