On Tue, Nov 2, 2021 at 5:26 AM Jason Wang <jasow...@redhat.com> wrote: > > > 在 2021/10/30 上午2:34, Eugenio Pérez 写道: > > This series enable shadow virtqueue (SVQ) for vhost-vdpa devices. This > > is intended as a new method of tracking the memory the devices touch > > during a migration process: Instead of relay on vhost device's dirty > > logging capability, SVQ intercepts the VQ dataplane forwarding the > > descriptors between VM and device. This way qemu is the effective > > writer of guests memory, like in qemu's virtio device operation. > > > > When SVQ is enabled qemu offers a new virtual address space to the > > device to read and write into, and it maps new vrings and the guest > > memory in it. SVQ also intercepts kicks and calls between the device > > and the guest. Used buffers relay would cause dirty memory being > > tracked, but at this RFC SVQ is not enabled on migration automatically. > > > > Thanks of being a buffers relay system, SVQ can be used also to > > communicate devices and drivers with different capabilities, like > > devices that only supports packed vring and not split and old guest > > with no driver packed support. > > > > It is based on the ideas of DPDK SW assisted LM, in the series of > > DPDK's https://patchwork.dpdk.org/cover/48370/ . However, these does > > not map the shadow vq in guest's VA, but in qemu's. > > > > For qemu to use shadow virtqueues the guest virtio driver must not use > > features like event_idx. > > > > SVQ needs to be enabled with QMP command: > > > > { "execute": "x-vhost-set-shadow-vq", > > "arguments": { "name": "vhost-vdpa0", "enable": true } } > > > > This series includes some patches to delete in the final version that > > helps with its testing. The first two of the series have been sent > > sepparately but they haven't been included in qemu main branch. > > > > The two after them adds the feature to stop the device and be able to > > set and get its status. It's intended to be used with vp_vpda driver in > > a nested environment, so they are also external to this series. The > > vp_vdpa driver also need modifications to forward the new status bit, > > they will be proposed sepparately > > > > Patches 5-12 prepares the SVQ and QMP command to support guest to host > > notifications forwarding. If the SVQ is enabled with these ones > > applied and the device supports it, that part can be tested in > > isolation (for example, with networking), hopping through SVQ. > > > > Same thing is true with patches 13-17, but with device to guest > > notifications. > > > > Based on them, patches from 18 to 22 implement the actual buffer > > forwarding, using some features already introduced in previous. > > However, they will need a host device with no iommu, something that > > is not available at the moment. > > > > The last part of the series uses properly the host iommu, so the driver > > can access this new virtual address space created. > > > > Comments are welcome. > > > I think we need do some benchmark to see the performance impact. > > Thanks >
Ok, I will add them for the next revision. Thanks! > > > > > TODO: > > * Event, indirect, packed, and others features of virtio. > > * To sepparate buffers forwarding in its own AIO context, so we can > > throw more threads to that task and we don't need to stop the main > > event loop. > > * Support multiqueue virtio-net vdpa. > > * Proper documentation. > > > > Changes from v4 RFC: > > * Support of allocating / freeing iova ranges in IOVA tree. Extending > > already present iova-tree for that. > > * Proper validation of guest features. Now SVQ can negotiate a > > different set of features with the device when enabled. > > * Support of host notifiers memory regions > > * Handling of SVQ full queue in case guest's descriptors span to > > different memory regions (qemu's VA chunks). > > * Flush pending used buffers at end of SVQ operation. > > * QMP command now looks by NetClientState name. Other devices will need > > to implement it's way to enable vdpa. > > * Rename QMP command to set, so it looks more like a way of working > > * Better use of qemu error system > > * Make a few assertions proper error-handling paths. > > * Add more documentation > > * Less coupling of virtio / vhost, that could cause friction on changes > > * Addressed many other small comments and small fixes. > > > > Changes from v3 RFC: > > * Move everything to vhost-vdpa backend. A big change, this allowed > > some cleanup but more code has been added in other places. > > * More use of glib utilities, especially to manage memory. > > v3 link: > > https://lists.nongnu.org/archive/html/qemu-devel/2021-05/msg06032.html > > > > Changes from v2 RFC: > > * Adding vhost-vdpa devices support > > * Fixed some memory leaks pointed by different comments > > v2 link: > > https://lists.nongnu.org/archive/html/qemu-devel/2021-03/msg05600.html > > > > Changes from v1 RFC: > > * Use QMP instead of migration to start SVQ mode. > > * Only accepting IOMMU devices, closer behavior with target devices > > (vDPA) > > * Fix invalid masking/unmasking of vhost call fd. > > * Use of proper methods for synchronization. > > * No need to modify VirtIO device code, all of the changes are > > contained in vhost code. > > * Delete superfluous code. > > * An intermediate RFC was sent with only the notifications forwarding > > changes. It can be seen in > > https://patchew.org/QEMU/20210129205415.876290-1-epere...@redhat.com/ > > v1 link: > > https://lists.gnu.org/archive/html/qemu-devel/2020-11/msg05372.html > > > > Eugenio Pérez (20): > > virtio: Add VIRTIO_F_QUEUE_STATE > > virtio-net: Honor VIRTIO_CONFIG_S_DEVICE_STOPPED > > virtio: Add virtio_queue_is_host_notifier_enabled > > vhost: Make vhost_virtqueue_{start,stop} public > > vhost: Add x-vhost-enable-shadow-vq qmp > > vhost: Add VhostShadowVirtqueue > > vdpa: Register vdpa devices in a list > > vhost: Route guest->host notification through shadow virtqueue > > Add vhost_svq_get_svq_call_notifier > > Add vhost_svq_set_guest_call_notifier > > vdpa: Save call_fd in vhost-vdpa > > vhost-vdpa: Take into account SVQ in vhost_vdpa_set_vring_call > > vhost: Route host->guest notification through shadow virtqueue > > virtio: Add vhost_shadow_vq_get_vring_addr > > vdpa: Save host and guest features > > vhost: Add vhost_svq_valid_device_features to shadow vq > > vhost: Shadow virtqueue buffers forwarding > > vhost: Add VhostIOVATree > > vhost: Use a tree to store memory mappings > > vdpa: Add custom IOTLB translations to SVQ > > > > Eugenio Pérez (26): > > util: Make some iova_tree parameters const > > vhost: Fix last queue index of devices with no cvq > > virtio: Add VIRTIO_F_QUEUE_STATE > > virtio-net: Honor VIRTIO_CONFIG_S_DEVICE_STOPPED > > vhost: Add x-vhost-set-shadow-vq qmp > > vhost: Add VhostShadowVirtqueue > > vdpa: Save kick_fd in vhost-vdpa > > vdpa: Add vhost_svq_get_dev_kick_notifier > > vdpa: Add vhost_svq_set_svq_kick_fd > > vhost: Add Shadow VirtQueue kick forwarding capabilities > > vhost: Handle host notifiers in SVQ > > vhost: Route guest->host notification through shadow virtqueue > > Add vhost_svq_get_svq_call_notifier > > Add vhost_svq_set_guest_call_notifier > > vdpa: Save call_fd in vhost-vdpa > > vhost-vdpa: Take into account SVQ in vhost_vdpa_set_vring_call > > vhost: Route host->guest notification through shadow virtqueue > > virtio: Add vhost_shadow_vq_get_vring_addr > > vdpa: ack VIRTIO_F_QUEUE_STATE if device supports it > > vhost: Add vhost_svq_valid_device_features to shadow vq > > vhost: Add vhost_svq_valid_guest_features to shadow vq > > vhost: Shadow virtqueue buffers forwarding > > util: Add iova_tree_alloc > > vhost: Add VhostIOVATree > > vhost: Use a tree to store memory mappings > > vdpa: Add custom IOTLB translations to SVQ > > > > qapi/net.json | 20 + > > hw/virtio/vhost-iova-tree.h | 27 + > > hw/virtio/vhost-shadow-virtqueue.h | 44 ++ > > hw/virtio/virtio-pci.h | 1 + > > include/hw/virtio/vhost-vdpa.h | 12 + > > include/hw/virtio/virtio.h | 4 +- > > include/qemu/iova-tree.h | 25 +- > > .../standard-headers/linux/virtio_config.h | 5 + > > include/standard-headers/linux/virtio_pci.h | 2 + > > hw/i386/intel_iommu.c | 2 +- > > hw/net/vhost_net.c | 2 +- > > hw/net/virtio-net.c | 6 +- > > hw/virtio/vhost-iova-tree.c | 157 ++++ > > hw/virtio/vhost-shadow-virtqueue.c | 746 ++++++++++++++++++ > > hw/virtio/vhost-vdpa.c | 437 +++++++++- > > hw/virtio/virtio-pci.c | 16 +- > > net/vhost-vdpa.c | 28 + > > util/iova-tree.c | 151 +++- > > hw/virtio/meson.build | 2 +- > > 19 files changed, 1664 insertions(+), 23 deletions(-) > > create mode 100644 hw/virtio/vhost-iova-tree.h > > create mode 100644 hw/virtio/vhost-shadow-virtqueue.h > > create mode 100644 hw/virtio/vhost-iova-tree.c > > create mode 100644 hw/virtio/vhost-shadow-virtqueue.c > > >
