From: Jason Wang <jasowang@redhat.com> To: Jason Gunthorpe <jgg@mellanox.com> Cc: Shahaf Shuler <shahafs@mellanox.com>, Rob Miller <rob.miller@broadcom.com>, "Michael S. Tsirkin" <mst@redhat.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 <netdev@vger.kernel.org>, "Bie, Tiwei" <tiwei.bie@intel.com>, "maxime.coquelin@redhat.com" <maxime.coquelin@redhat.com>, "Liang, Cunming" <cunming.liang@intel.com>, "Wang, Zhihong" <zhihong.wang@intel.com>, "Wang, Xiao W" <xiao.w.wang@intel.com>, "haotian.wang@sifive.com" <haotian.wang@sifive.com>, "Zhu, Lingshan" <lingshan.zhu@intel.com>, "eperezma@redhat.com" <eperezma@redhat.com>, "lulu@redhat.com" <lulu@redhat.com>, Parav Pandit <parav@mellanox.com>, "Tian, Kevin" <kevin.tian@intel.com>, "stefanha@redhat.com" <stefanha@redhat.com>, "rdunlap@infradead.org" <rdunlap@infradead.org>, "hch@infradead.org" <hch@infradead.org>, Ariel Adam <aadam@redhat.com>, "jakub.kicinski@netronome.com" <jakub.kicinski@netronome.com>, Jiri Pirko <jiri@mellanox.com>, "hanand@xilinx.com" <hanand@xilinx.com>, "mhabets@solarflare.com" <mhabets@solarflare.com> Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus Date: Tue, 21 Jan 2020 12:00:57 +0800 Message-ID: <2a324cec-2863-58f4-c58a-2414ee32c930@redhat.com> (raw) In-Reply-To: <20200120174933.GB3891@mellanox.com> On 2020/1/21 上午1:49, Jason Gunthorpe wrote: > On Mon, Jan 20, 2020 at 04:43:53PM +0800, Jason Wang wrote: >> This is similar to the design of platform IOMMU part of vhost-vdpa. We >> decide to send diffs to platform IOMMU there. If it's ok to do that in >> driver, we can replace set_map with incremental API like map()/unmap(). >> >> Then driver need to maintain rbtree itself. > I think we really need to see two modes, one where there is a fixed > translation without dynamic vIOMMU driven changes and one that > supports vIOMMU. I think in this case, you meant the method proposed by Shahaf that sends diffs of "fixed translation" to device? It would be kind of tricky to deal with the following case for example: old map [4G, 16G) new map [4G, 8G) If we do 1) flush [4G, 16G) 2) add [4G, 8G) There could be a window between 1) and 2). It requires the IOMMU that can do 1) remove [8G, 16G) 2) flush [8G, 16G) 3) change [4G, 8G) .... > > There are different optimization goals in the drivers for these two > configurations. > >>> If the first one, then I think memory hotplug is a heavy flow >>> regardless. Do you think the extra cycles for the tree traverse >>> will be visible in any way? >> I think if the driver can pause the DMA during the time for setting up new >> mapping, it should be fine. > This is very tricky for any driver if the mapping change hits the > virtio rings. :( > > Even a IOMMU using driver is going to have problems with that.. > > Jason Or I wonder whether ATS/PRI can help here. E.g during I/O page fault, driver/device can wait for the new mapping to be set and then replay the DMA. Thanks >
next prev parent 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 [this message] 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 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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