From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Shahaf Shuler <shahafs@mellanox.com>,
Tiwei Bie <tiwei.bie@intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"virtualization@lists.linux-foundation.org"
<virtualization@lists.linux-foundation.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Jason Gunthorpe <jgg@mellanox.com>,
"rob.miller@broadcom.com" <rob.miller@broadcom.com>,
"haotian.wang@sifive.com" <haotian.wang@sifive.com>,
"eperezma@redhat.com" <eperezma@redhat.com>,
"lulu@redhat.com" <lulu@redhat.com>,
Parav Pandit <parav@mellanox.com>,
"rdunlap@infradead.org" <rdunlap@infradead.org>,
"hch@infradead.org" <hch@infradead.org>,
Jiri Pirko <jiri@mellanox.com>,
"hanand@xilinx.com" <hanand@xilinx.com>,
"mhabets@solarflare.com" <mhabets@solarflare.com>,
"maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>,
"lingshan.zhu@intel.com" <lingshan.zhu@intel.com>,
"dan.daly@intel.com" <dan.daly@intel.com>,
"cunming.liang@intel.com" <cunming.liang@intel.com>,
"zhihong.wang@intel.com" <zhihong.wang@intel.com>
Subject: Re: [PATCH] vhost: introduce vDPA based backend
Date: Wed, 5 Feb 2020 04:23:59 -0500 [thread overview]
Message-ID: <20200205042259-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <112858a4-1a01-f4d7-e41a-1afaaa1cad45@redhat.com>
On Wed, Feb 05, 2020 at 03:50:14PM +0800, Jason Wang wrote:
>
> On 2020/2/5 下午3:15, Shahaf Shuler wrote:
> > Wednesday, February 5, 2020 4:03 AM, Tiwei Bie:
> > > Subject: Re: [PATCH] vhost: introduce vDPA based backend
> > >
> > > On Tue, Feb 04, 2020 at 11:30:11AM +0800, Jason Wang wrote:
> > > > On 2020/1/31 上午11:36, Tiwei Bie wrote:
> > > > > This patch introduces a vDPA based vhost backend. This backend is
> > > > > built on top of the same interface defined in virtio-vDPA and
> > > > > provides a generic vhost interface for userspace to accelerate the
> > > > > virtio devices in guest.
> > > > >
> > > > > This backend is implemented as a vDPA device driver on top of the
> > > > > same ops used in virtio-vDPA. It will create char device entry named
> > > > > vhost-vdpa/$vdpa_device_index for userspace to use. Userspace can
> > > > > use vhost ioctls on top of this char device to setup the backend.
> > > > >
> > > > > Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> > [...]
> >
> > > > > +static long vhost_vdpa_do_dma_mapping(struct vhost_vdpa *v) {
> > > > > + /* TODO: fix this */
> > > >
> > > > Before trying to do this it looks to me we need the following during
> > > > the probe
> > > >
> > > > 1) if set_map() is not supported by the vDPA device probe the IOMMU
> > > > that is supported by the vDPA device
> > > > 2) allocate IOMMU domain
> > > >
> > > > And then:
> > > >
> > > > 3) pin pages through GUP and do proper accounting
> > > > 4) store GPA->HPA mapping in the umem
> > > > 5) generate diffs of memory table and using IOMMU API to setup the dma
> > > > mapping in this method
> > > >
> > > > For 1), I'm not sure parent is sufficient for to doing this or need to
> > > > introduce new API like iommu_device in mdev.
> > > Agree. We may also need to introduce something like the iommu_device.
> > >
> > Would it be better for the map/umnap logic to happen inside each device ?
> > Devices that needs the IOMMU will call iommu APIs from inside the driver callback.
>
>
> Technically, this can work. But if it can be done by vhost-vpda it will make
> the vDPA driver more compact and easier to be implemented.
>
>
> > Devices that has other ways to do the DMA mapping will call the proprietary APIs.
>
>
> To confirm, do you prefer:
>
> 1) map/unmap
>
> or
>
> 2) pass all maps at one time?
>
> Thanks
>
>
I mean we really already have both right? ATM 1 is used with an iommu
and 2 without. I guess we can also have drivers ask for either or both
...
--
MST
next prev parent reply other threads:[~2020-02-05 9:24 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 3:36 [PATCH] vhost: introduce vDPA based backend Tiwei Bie
2020-01-31 3:56 ` Randy Dunlap
2020-01-31 5:12 ` Randy Dunlap
2020-01-31 5:54 ` Tiwei Bie
2020-01-31 5:52 ` Tiwei Bie
2020-02-04 3:30 ` Jason Wang
2020-02-04 6:01 ` Michael S. Tsirkin
2020-02-04 6:46 ` Jason Wang
2020-02-05 2:05 ` Tiwei Bie
2020-02-05 3:12 ` Jason Wang
2020-02-05 5:31 ` Michael S. Tsirkin
2020-02-05 5:50 ` Jason Wang
2020-02-05 6:30 ` Michael S. Tsirkin
2020-02-05 6:49 ` Jason Wang
2020-02-05 7:16 ` Michael S. Tsirkin
2020-02-05 7:42 ` Jason Wang
2020-02-05 9:22 ` Michael S. Tsirkin
2020-02-05 2:02 ` Tiwei Bie
2020-02-05 3:11 ` Jason Wang
2020-02-05 7:15 ` Shahaf Shuler
2020-02-05 7:50 ` Jason Wang
2020-02-05 9:23 ` Michael S. Tsirkin [this message]
2020-02-06 3:07 ` Jason Wang
2020-02-05 9:30 ` Shahaf Shuler
2020-02-05 10:33 ` Michael S. Tsirkin
2020-02-06 3:09 ` Jason Wang
2020-02-06 3:04 ` Jason Wang
2020-02-05 12:56 ` Jason Gunthorpe
2020-02-05 13:14 ` Michael S. Tsirkin
2020-02-06 3:11 ` Jason Wang
2020-02-06 3:21 ` Zhu Lingshan
2020-02-18 13:53 ` Jason Gunthorpe
2020-02-19 2:52 ` Tiwei Bie
2020-02-19 13:11 ` Jason Gunthorpe
2020-02-20 2:42 ` Tiwei Bie
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