From: Jason Wang <jasowang@redhat.com> To: "Michael S. Tsirkin" <mst@redhat.com>, Jason Gunthorpe <jgg@mellanox.com> Cc: Shahaf Shuler <shahafs@mellanox.com>, Rob Miller <rob.miller@broadcom.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: Wed, 22 Jan 2020 14:18:01 +0800 [thread overview] Message-ID: <26fa6211-6625-6dc6-f5df-7a124d8c53ae@redhat.com> (raw) In-Reply-To: <20200121091636-mutt-send-email-mst@kernel.org> On 2020/1/21 下午10:17, Michael S. Tsirkin wrote: > On Tue, Jan 21, 2020 at 02:05:04PM +0000, Jason Gunthorpe wrote: >> On Tue, Jan 21, 2020 at 03:15:43AM -0500, Michael S. Tsirkin wrote: >>>> This sounds more flexible e.g driver may choose to implement static mapping >>>> one through commit. But a question here, it looks to me this still requires >>>> the DMA to be synced with at least commit here. Otherwise device may get DMA >>>> fault? Or device is expected to be paused DMA during begin? >>>> >>>> Thanks >>> For example, commit might switch one set of tables for another, >>> without need to pause DMA. >> I'm not aware of any hardware that can do something like this >> completely atomically.. > FWIW VTD can do this atomically. > >> Any mapping change API has to be based around add/remove regions >> without any active DMA (ie active DMA is a guest error the guest can >> be crashed if it does this) >> >> Jason > Right, lots of cases are well served by only changing parts of > mapping that aren't in active use. Memory hotplug is such a case. > That's not the same as a completely static mapping. For hotplug it should be fine with current Qemu since it belongs to different memory regions. So each dimm should have its own dedicated map entries in IOMMU. But I'm not sure if the merging logic in current vhost memory listener may cause any trouble, we may need to disable it. Thanks >
WARNING: multiple messages have this Message-ID (diff)
From: Jason Wang <jasowang@redhat.com> To: "Michael S. Tsirkin" <mst@redhat.com>, Jason Gunthorpe <jgg@mellanox.com> Cc: Shahaf Shuler <shahafs@mellanox.com>, Rob Miller <rob.miller@broadcom.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> Subject: Re: [PATCH 3/5] vDPA: introduce vDPA bus Date: Wed, 22 Jan 2020 14:18:01 +0800 [thread overview] Message-ID: <26fa6211-6625-6dc6-f5df-7a124d8c53ae@redhat.com> (raw) In-Reply-To: <20200121091636-mutt-send-email-mst@kernel.org> On 2020/1/21 下午10:17, Michael S. Tsirkin wrote: > On Tue, Jan 21, 2020 at 02:05:04PM +0000, Jason Gunthorpe wrote: >> On Tue, Jan 21, 2020 at 03:15:43AM -0500, Michael S. Tsirkin wrote: >>>> This sounds more flexible e.g driver may choose to implement static mapping >>>> one through commit. But a question here, it looks to me this still requires >>>> the DMA to be synced with at least commit here. Otherwise device may get DMA >>>> fault? Or device is expected to be paused DMA during begin? >>>> >>>> Thanks >>> For example, commit might switch one set of tables for another, >>> without need to pause DMA. >> I'm not aware of any hardware that can do something like this >> completely atomically.. > FWIW VTD can do this atomically. > >> Any mapping change API has to be based around add/remove regions >> without any active DMA (ie active DMA is a guest error the guest can >> be crashed if it does this) >> >> Jason > Right, lots of cases are well served by only changing parts of > mapping that aren't in active use. Memory hotplug is such a case. > That's not the same as a completely static mapping. For hotplug it should be fine with current Qemu since it belongs to different memory regions. So each dimm should have its own dedicated map entries in IOMMU. But I'm not sure if the merging logic in current vhost memory listener may cause any trouble, we may need to disable it. Thanks >
next prev parent reply other threads:[~2020-01-22 6:18 UTC|newest] Thread overview: 141+ 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 0:01 ` kbuild test robot 2020-01-18 0:01 ` kbuild test robot 2020-01-18 0:40 ` kbuild test robot 2020-01-18 0:40 ` 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 21:54 ` kbuild test robot 2020-01-17 21:54 ` kbuild test robot 2020-01-17 22:33 ` kbuild test robot 2020-01-17 22:33 ` 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 2020-01-16 15:22 ` Jason Gunthorpe 2020-01-17 3:03 ` Jason Wang 2020-01-17 3:03 ` Jason Wang 2020-01-17 13:54 ` Jason Gunthorpe 2020-01-17 13:54 ` Jason Gunthorpe 2020-01-20 7:50 ` Jason Wang 2020-01-20 7:50 ` Jason Wang 2020-01-20 12:17 ` Michael S. Tsirkin 2020-01-20 12:17 ` Michael S. Tsirkin 2020-01-20 17:50 ` Jason Gunthorpe 2020-01-20 17:50 ` Jason Gunthorpe 2020-01-20 21:56 ` Michael S. Tsirkin 2020-01-20 21:56 ` Michael S. Tsirkin 2020-01-21 14:12 ` Jason Gunthorpe 2020-01-21 14:12 ` Jason Gunthorpe 2020-01-21 14:15 ` Michael S. Tsirkin 2020-01-21 14:15 ` Michael S. Tsirkin 2020-01-21 14:16 ` Jason Gunthorpe 2020-01-21 14:16 ` Jason Gunthorpe 2020-01-21 8:40 ` Tian, Kevin 2020-01-21 8:40 ` Tian, Kevin 2020-01-21 9:41 ` Jason Wang 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 2020-01-17 14:12 ` Rob Miller via Virtualization 2020-01-19 9:07 ` Shahaf Shuler 2020-01-19 9:07 ` Shahaf Shuler 2020-01-19 9:59 ` Michael S. Tsirkin 2020-01-19 9:59 ` Michael S. Tsirkin 2020-01-20 8:44 ` Jason Wang 2020-01-20 8:44 ` Jason Wang 2020-01-20 12:09 ` Michael S. Tsirkin 2020-01-20 12:09 ` Michael S. Tsirkin 2020-01-21 3:32 ` Jason Wang 2020-01-21 3:32 ` Jason Wang 2020-01-20 8:43 ` Jason Wang 2020-01-20 8:43 ` Jason Wang 2020-01-20 17:49 ` Jason Gunthorpe 2020-01-20 17:49 ` Jason Gunthorpe 2020-01-20 20:51 ` Shahaf Shuler 2020-01-20 20:51 ` Shahaf Shuler 2020-01-20 21:25 ` Michael S. Tsirkin 2020-01-20 21:25 ` Michael S. Tsirkin 2020-01-20 21:47 ` Shahaf Shuler 2020-01-20 21:47 ` Shahaf Shuler 2020-01-20 21:59 ` Michael S. Tsirkin 2020-01-20 21:59 ` Michael S. Tsirkin 2020-01-21 6:01 ` Shahaf Shuler 2020-01-21 6:01 ` Shahaf Shuler 2020-01-21 7:57 ` Jason Wang 2020-01-21 7:57 ` Jason Wang 2020-01-21 14:07 ` Jason Gunthorpe 2020-01-21 14:07 ` Jason Gunthorpe 2020-01-21 14:16 ` Michael S. Tsirkin 2020-01-21 14:16 ` Michael S. Tsirkin 2020-01-20 21:48 ` Michael S. Tsirkin 2020-01-20 21:48 ` Michael S. Tsirkin 2020-01-21 4:00 ` Jason Wang 2020-01-21 4:00 ` Jason Wang 2020-01-21 5:47 ` Michael S. Tsirkin 2020-01-21 5:47 ` Michael S. Tsirkin 2020-01-21 8:00 ` Jason Wang 2020-01-21 8:00 ` Jason Wang 2020-01-21 8:15 ` Michael S. Tsirkin 2020-01-21 8:15 ` Michael S. Tsirkin 2020-01-21 8:35 ` Jason Wang 2020-01-21 8:35 ` Jason Wang 2020-01-21 11:09 ` Shahaf Shuler 2020-01-21 11:09 ` Shahaf Shuler 2020-01-22 6:36 ` Jason Wang 2020-01-22 6:36 ` Jason Wang 2020-01-21 14:05 ` Jason Gunthorpe 2020-01-21 14:05 ` Jason Gunthorpe 2020-01-21 14:17 ` Michael S. Tsirkin 2020-01-21 14:17 ` Michael S. Tsirkin 2020-01-22 6:18 ` Jason Wang [this message] 2020-01-22 6:18 ` Jason Wang 2020-01-20 8:19 ` 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 2020-01-16 15:38 ` Jason Gunthorpe 2020-01-17 9:32 ` Jason Wang 2020-01-17 9:32 ` Jason Wang 2020-01-17 14:00 ` Jason Gunthorpe 2020-01-17 14:00 ` Jason Gunthorpe 2020-01-20 7:52 ` Jason Wang 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 2020-01-16 15:47 ` Jason Gunthorpe 2020-01-17 9:32 ` Jason Wang 2020-01-17 9:32 ` Jason Wang 2020-01-17 14:10 ` Jason Gunthorpe 2020-01-17 14:10 ` Jason Gunthorpe 2020-01-20 8:01 ` Jason Wang 2020-01-20 8:01 ` Jason Wang 2020-02-04 4:19 ` 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 2020-01-18 18:18 ` kbuild test robot 2020-01-18 18:18 ` kbuild test robot 2020-01-28 3:32 ` Dan Carpenter 2020-01-28 3:32 ` Dan Carpenter 2020-01-28 3:32 ` Dan Carpenter 2020-01-28 3:32 ` Dan Carpenter 2020-02-04 4:07 ` Jason Wang 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 8:44 ` Tian, Kevin 2020-01-21 9:39 ` Jason Wang 2020-01-21 9:39 ` Jason Wang
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